Alexis Michaud

Jacqueline Vaissière

Rachid Ridouane

Balthazar Séverine Guillaume

Do Nascimento

Zlatka Guentchéva-Desclés

Benjamin Galliot

Isabelle Bril

Anne Armand

Vera Scholvin

Albert Badosa Roldós

Valentina Alfarano

Camille Simon

Fatima Zahra Issaiene

Mezane Konuk

Maxime Fily

Neige Rochant

Yann Le Moullec

Eréndira Calderon

Alexandra Vydrina

as well as the Vietnamese Cécile Macaire

Marc Brunelle

Phạm Thị

Thu Hà

Tạ Thành

Lê Thị

Vũ-Xuân Xuyến

Mark Alves

Guillaume Jacques

Keywords: glottalization, creaky voice, phonation types, tone systems, experimental phonology, phonetic fieldwork, electroglottography, Vietic languages, Muong language i langues viétiques, langue muong, systèmes de tons, types de voix, glottalisation, voix craquée, phonétique expérimentale, électroglottographie iii

Glottalization, tonal contrasts and intonation: an experimental study of the Kim Thuong dialect of Muong

All languages in the Vietic subbranch of Austroasiatic have at least one glottalized tone. This thesis zooms in on one of these languages: Muong (in Vietnamese orthography:

Mường, endonym: /mon³/), spoken in Kim Thuong (Phu Tho, Vietnam). Twenty speakers recorded twelve tonal minimal sets of the five tones of smooth syllables, plus three tonal minimal pairs of the two tones of checked syllables, under two conditions: in isolation and in a carrier sentence. Acoustic and electroglottographic recordings allow for estimating fundamental frequency, glottal open quotient and duration. These parameters are compared across tones, experimental conditions and speakers, in order to contribute to a better understanding of glottalization as a feature of linguistic tones. First, allotones of the phonologically glottalized tone in Muong (Tone 4) are classified on a phonetic basis, confirming the consistent presence of creak. It is tempting to contrast it with the glottally constricted tones of Northern Vietnamese (with which Muong is in sustained language contact). However, the phonological discussion emphasizes that analysis of Tone 4 as a prototypical "creaky tone" would be a pitfall. Tone 4 behaves in key respects like the other tones in the system: it is not defined solely by phonation type.

Moreover, the range of phonetic (allotonic) variation of Tone 4 includes cases of glottal constriction. Use of a phonetic nomenclature for types of glottalization serves as a basis for describing the interaction of glottalization with intonation.

2.19 Tone box of Kim Thuong Muong . . . . . . . . . . . . . . . . . . . . . . . . 3.1 General outline of the f 0 curve of an affirmative statement [START_REF] Vaissière | Language-independent prosodic features[END_REF]. Reproduced from [START_REF] Vaissière | Prosodic constituents in French: a datadriven approach[END_REF], with permission. . 3.16 The difference between two versions (2016 and 2019) of the initial settings in the Command Window after executing PeaKDet. . . . . . . . . . . 3.17 A demo of four initial plots after automatic processing of a token by PeaKDet. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation. . . . . . . . . . . . . . . . . 3.18 Together with four plots as in Figure 3.17, the display of the current processing token on Command Window with identification information, f 0 dEGG information and f 0 dEGG processing options. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation. .

Introduction

The study of glottalization, tonal contrasts and intonation in the Muong language (Kim Thuong Muong 1 ) stands at the intersection of several fields, each of which has motivations, objectives, methods and requirements of its own: experimental phonetics/phonology (specifically, the study of tones and phonation types), language documentation and conservation, language description, and areal studies (Southeast Asian linguistics). These main strands are presented separately below. They set the stage for the research question addressed in the present thesis, which is presented in 1.7.

Linguistic uses of phonation types

The study of phonation types has consistently been a topical issue in phonetics and phonology over past decades, due in no small part to their relevance to expressive speech and hence to high-quality speech synthesis [START_REF] Erickson | Expressive speech: Production, perception and application to speech synthesis[END_REF]. Specifically, glottalization serves pragmatic, stylistic and attitudinal functions, to different extents in different languages: thus, creaky voice is less prevalent in present-day French than in presentday English, with American English having more creak than British English (for a review, and some fresh evidence, see [START_REF] Pillot-Loiseau | The evolution of creaky voice use in read speech by native-French and native-English speakers in tandem: a pilot study[END_REF]. But the attention of phoneticians/phonologists had been drawn to phonation types at least since the middle of the 20th century, when their role in some phonological systems was brought out. Eugénie Henderson brought out the key role of phonation-type registers in the evolution of Cambodian [START_REF] Henderson | The main features of Cambodian pronunciation[END_REF], an insight which proved fruitful for a wide range of other languages of Southeast Asia, in the Austroasiatic family (for an overview [START_REF] Ferlus | Formation des registres et mutations consonantiques dans les langues mon-khmer[END_REF] and beyond (on the case of Chru, an Austroasiatic language: Brunelle, Thành [START_REF] Brunelle | Transphonologization of voicing in Chru: Studies in production and perception[END_REF]. The present study is intended as a contribution to the latter strand of research: investigating a language where phonation (specifically: the use of creaky voice) plays a phonologically distinctive role as a part of the tone system.

The presence of one form or other of glottalization is a common characteristic of languages of the Vietic group 2 (Ferlus, 1998), so, as seen from Southeast Asia, it really 1 Place names in Vietnam are provided in Vietnamese orthography, at least at first occurrence, for clarity of reference. Vietnamese author names are reproduced as they stand in the original. 2 The Vietic languages are a branch of the Austroasiatic language family. The branch was once referred to by the terms Viet-Muong, Annamese-Muong, and Vietnamuong. The term 'Vietic' was proposed by [START_REF] Hayes | Vietic and Việt-Mường: a new subgrouping in Mon-Khmer[END_REF], who proposed to redefine Viet-Muong as referring to a sub-branch of Vietic 1 does not appear as an out-of-the-way situation. The realization that glottalization plays a role in Vietnamese tone dates back at least to de Rhodes's 17 th century Dictionary [START_REF] Rhodes | Dictionarium Annamiticum Lusitanum et Latinum[END_REF]. This property, which has been lost in the Southern dialect of Vietnamese, is still present in the Northern dialect (Brunelle, 2009a). The present study of Kim Thuong Muong aims to bring out how the linguistic categories match the phonetic diversity of observed phonation types. In the case of the five lexical tones of Kim Thuong Muong, an initial expectation is that creak will be mostly found on Tone 4 syllables, but also bracing ourselves for the possible encounter of complex combinations of factors, including interaction between tones (some of which incorporate phonation-type specifications) and intonation.

Phonation types, tones and intonation

It was mentioned in 2.2 that phonation types have been a topical issue in phonetic research in recent years. The interaction of lexical tones and intonation likewise appears as a topic of enduring interest. This interest may be due in part to the simple reason that linguists who do not speak a tonal language natively encounter such languages in their studies and readings, and naturally come to realize that "[a]s tone and intonation, which have different functions, are materialized simultaneously by the use of pitch variation, interaction between the two is expected to occur" (W.-S. Lee and Zee, 2017, p. 345).

The same lexical tones are expected to be realized somewhat differently in different intonational contexts. In language groups where tone can be described in terms of pitch alone, the interplay of tone and intonation is reported to be language-and dialect-specific. The well-studied area of Sinitic languages (Chinese dialects) provides solid evidence on this topic: the phrasing adopted by W.-S. Lee and E. Zee, "the effect of intonation on tone differs in different Chinese dialects" (W.-S. Lee and Zee, 2017, p. 349), does not appear controversial. Precious insights are to be found from case studies of this vast language group: for instance, the tone contours of individual syllables are better preserved across sentence modes (declarative vs. interrogative) in Beijing Mandarin than in the (otherwise very similar) Mandarin dialect spoken in Chengdu, in Southwest China (ibid.).

The presence of phonation types as part of the phonological specifications of tones (as in Muong) adds another twist to the fascinating issue of the interaction between tone and intonation. How is the use of creaky voice modulated intonationally in a language where it plays a role in the tone system? This topic links up with so many dimensions of intonation (phrasing and prominence, but also sentence mode, attitudes, emotions and rhythm) that answers provided here are bound to be incomplete, if only because a considerable range of different experimental setups would be required to shed light on all these different dimensions. However, the topic is so pervasive in communication in the Muong language that literally any set of materials in Muong containing only Vietnamese and Muong. This usage has become most widespread, and is followed here.

Language documentation and conservation in present-day Southeast Asia

sheds some light on the issue. Even elicited materials such as a word list allow for insights, because even a word in isolation constitutes an utterance, and its realization is thereby complete with word-level and utterance-level intonational trammings that reflect the attitude with which it is uttered (more or less assertive, more or less cautious, and so on), and also phonetic correlates of sentence-level phenomena (junctures), in addition to its lexical tone. Seen in this light, the topic of the role played by creaky voice in communication in the Muong language does not appear as hopelessly complex: its complexity is real, but it is made up of smaller complexities, and the tried-and-tested scientific approach that consists of examining different issues separately constitutes a good guide to progress in this field. In this perspective, the obvious limitations of the materials used in this study (mostly tonal minimal sets in carrier sentences) also entail advantages in terms of ease of analysis. It does not appear unreasonable to start out from such materials, rather than confront headlong all topics at once by focusing primarily on samples of dialogues, as one might be tempted to do in view of the creativity found in lively dialogues.

It nonetheless appeared advisable to cast the net wide at the stage of data collection, and to record materials that are not limited to one context of elicitation: an interesting research question is to what extent spontaneous speech differs from materials that are elicited sentence by sentence with a strong efforts towards symmetry.

Mention of the balance (or lack of such) between different types of materials recorded for this study provides a handy transition to the topic of the contribution that the present study intends to make to language documentation and conservation, two dimensions of the activity of linguists which matter more than ever in a time of accelerating worldwide attrition of the diversity of languages and culture.

Language documentation and conservation in present-day Southeast Asia

The study of minority ethnic languages, as they are known in Vietnam (and neighbouring countries), is itself a 'minority' discipline within linguistics, with few people in the field, especially given the large number of languages that are currently on the wane in Southeast Asia (Enfield and Comrie, 2015, p. 12). Of course, what would really need to be done is to safeguard language diversity, for reasons that are obvious to scientists reflecting on the issue.

The knowledge systems and practices of Indigenous Peoples and local communities play critical roles in safeguarding the biological and cultural diversity of our planet. (…) Our warning raises the alarm about the pervasive and ubiquitous erosion of knowledge and practice and the social and ecological consequences of this erosion. (…) We appeal for urgent action to support the efforts of Indigenous Peoples and local communities around the world to maintain their knowledge systems, languages, stewardship rights, ties to lands and waters, and the biocultural integrity of their territorieson which we all depend. [START_REF] Fernández-Llamazares | Scientists' Warning to Humanity on Threats to Indigenous and Local Knowledge Systems[END_REF] While the overall picture leaves little ground for optimism concerning the preservation of language diversity, linguists are in a position to create at least a decent archival record of languages before they go out of human memory. "Documentary linguistics is concerned with the creation of a longlasting, multipurpose record of the language use of speakers/signers" (Seyfeddinipur and Rau, 2020, p. 503). The work reported in the present dissertation is admittedly by no means a typical contribution to language documentation, as its focus is especially narrow (a phonetic/phonological study of the tone system), but it is nonetheless designed as a contribution to language documentation. Phonological elicitation can arguably be integrated within language documentation, thereby improving the record.

Several open-access digital libraries were created with the purpose of storing research publications and related information about languages in the world. Specifically for Southeast Asian languages, the SEAlang projects,3 for "Southeast Asian Languages", was established in 2005. Its library provides language reference materials for Southeast Asia. Through 2009, it focused on the non-roman script languages used throughout the mainland, and in 2010-2013 it concentrated on the many languages of insular Southeast Asia, including Malaysia, Indonesia, and the Philippines. It is to be hoped that this ambitious project will continue over the years and decades. On a much more modest scale, interested scholars maintain a Zotero group (set up under the impetus of Mark Alves), which pools references on Vietic languages and linguistics: "Vietic Languages and Cultures". 4Attention paid to the endangered languages of Southeast Asia naturally links up with a concern for the conservation of language data.

As part of a project funded by the Comité pour la Science ouverte (formerly Bibliothèque scientifique Numérique), DO-RE-MI-FA (for Données des Recherches de Michel Ferlus en Asie du Sud-Est), 5 digitization and dissemination of Michel Ferlus's audio data from fieldwork was undertaken from 2014 to 2016. The project was conducted with the aim of bringing data collection of languages in Vietnam and neighboring countries to the research community. This was hailed as an important resource for research and cooperation among linguists, anthropologists and engineers. Due in no small part to the DO-RE-MI-FA project, there has been notable expansion of Southeast Asian language corpora in the Pangloss Collection (hosted by LACITO) over the past decade. 6 As a participant in the DO-RE-MI-FA project project, I had the honor of handling Ferlus's data of Mường language with a total of about 30 recordings 1. [START_REF]An example illustrates the unusual beginning of speaker M12's Tone 4 with unreasonably high f 0 dEGG values caused by micro-closing peaks[END_REF] Language description from eight different dialects, which were recorded starting in 1983. When conducting my own study, whose result is this dissertation, I had a desire to enrich this precious resource. All the materials collected for this dissertation are already archived in the Pangloss Collection (available here: https://pangloss.cnrs.fr/corpus/Mường).

Language description

For obvious reasons, it was not feasible to provide a well-rounded description of Muong within the frame of this dissertation. Writing a reference grammar constitutes full-time work (as does the writing of a study in experimental phonetics/phonology, which is the goal of the present dissertation). Such work is nonetheless an important long-term goal. It sets an overarching general plan for language description, which lends meaning to focused (even piecemeal) descriptive work such as the research on phonation types which constitutes the core of the present dissertation.

Among the three pieces which together constitute a full-fledged language description -the Boasian Trilogy, as it has been called -, the preparation of a dictionary has been initiated. Even though it currently remains at the stage of a word list, it is based on a solid framework provided by the EFEO-SOAS-CNRS wordlist [START_REF] Pain | EFEO-CNRS-SOAS word list for linguistic fieldwork in Southeast Asia[END_REF] and was devised with gradual expansion in view. The second part of the trilogy, a corpus of texts, is relatively modest, and still mostly untranscribed, but the collection process was set in train since the earliest stages of fieldwork. Each of the participants in the phonetic/phonological data collection campaign was also asked to provide narratives about life in the village or other topics familiar to them, and these materials provide an initial basis for well-rounded language documentation. As my command of the language progresses in future, I will increasingly be able to build on these materials, transcribe (with the help of consultants), translate and annotate, also recording new data, in a snowballing process that aims at serious coverage, following practices in descriptive and documentary linguistics.

Areal studies and typology in an Open Science perspective

For someone interested in living languages, working in a nationwide and worldwide context of language endangerment is a subject of sadness. Another reason for chagrin could be the necessity to choose among the many languages and research topics one is interested in. Devoting years of research to the tone system of just one dialect of one language within one branch of one language family can look desperatingly narrow in view of the wealth of possible directions for research and documentation.

Importantly, the perspective of Open Science gives a fundamental twist to this situation. As soon as publications (like the present Ph.D. dissertation) are not viewed as standalone deliverables by themselves, but as elements within an environment that also comprises data and tools [START_REF] Roettger | Emergent data analysis in phonetic sciences: Towards pluralism and reproducibility[END_REF], connecting studies together into wider patterns appears as a natural development. Typology and areal studies do not appear as separate strands of research, but as a straightforward continuation of research that is done well on the ground, at the level of individual languages and highly specific research topics. As soon as data are curated in such a way as to be shareable with other researchers, cumulative progress and facilitated scholarly dialogue appear as very real and very close prospects.

Acoustics, production and perception

Acoustics, production and perception should be studied jointly, as a matter of course. The present work contains no investigation of physiology, and no work on perception (apart from the investigator's constant use of aural impressions, of course); fundamental notions of acoustics are used, but this is not a work of fundamental research into acoustics or signal processing, unlike e.g. [START_REF] Henrich | Etude de la source glottique en voix parlée et chantée : modélisation et estimation, mesures acoustiques et électroglottographiques, perception[END_REF]. These limitations are hereby acknowledged as resulting, not from oversight, but from practical difficulties conducting fiberscopic video recordings of the vocal folds (preferably through high-frequency laryngoscopy) and other types of investigations. It is hoped that, by accepting the compromise of focusing solely on audio and electroglottographic evidence, the present study gained somewhat in reliability of the data that were recorded, even at the cost of a narrowed experimental scope.

Motivation and research questions

The six research strands mentioned above constitute the backdrop to the present study; contributing to these research strands is a strong motivation, from the short term to the long term. As for the specific research question addressed by the study, it is grounded in recent developments in the cross-linguistic study of linguistic uses of phonation types. Specifically, the research topic is formulated in view of recent proposals about a widely-studied tonal language: Mandarin Chinese. My initial intuition about the language studied here (Muong) is that its use of creak differs widely from what is observed in Mandarin, allowing for useful refinements to cross-linguistic (typological) models.

The use of phonation types has consistently been a topical concern in phonetics and phonology in recent decades. It is fascinating to observe that the same phonation type can play different functions in different languages. The object of the present study, glottalization in general and creaky voice in particular, is well-known for serving the function of indicating phrasing (cueing intonational junctures) in many languages, such as English [START_REF] Dilley | Glottalization of word-initial vowels as a function of prosodic structure[END_REF], Cantonese [START_REF] Yu | The role of creaky voice in Cantonese tonal perception[END_REF], and Mandarin (Kuang, 2017). The prevalence of this finding would suggest that it could turn out to be a linguistic universal.

However, the typological picture becomes more complex as one examines cases of non-modal phonation with phonemic function. Such cases are clearly a minority among the world's languages, and moreover occur in lesser-known languages, mostly in "exotic" languages. When phonemic tone is also involved, several types of relationships between non-modal phonation and tone are attested. A highly influential theory is that elaborated by [START_REF] Silverman | Phonetic structures in Jalapa Mazatec[END_REF] and [START_REF] Silverman | Phasing and recoverability[END_REF]. They point out that phonation-type characteristics and tone are perceptually recognizable ("recoverable") through a temporal arrangement ("phasing") that avoids the sort of confusion that would be expected in simultaneous production. Arranging tonal events and phonation-type changes in sequence (temporal phasing) makes them "segmentable" by the ear, so that each element can be perceptually recovered. Jalapa Mazatec is a key example for this theory (indeed, the theory seems tailored for cases like Jalapa Mazatec). On the other hand, another combination is not discussed by Silverman, but is firmly attested in East/Southeast Asian languages such as North Vietnamese (Michaud, 2004b;Brunelle, 2009b), Green Mong [START_REF] Andruski | Tone clarity in mixed pitch/phonation-type tones[END_REF] and White Hmong [START_REF] Garellek | Voice quality and tone identification in White Hmong[END_REF], where pitch and phonation type are two dimensions of the same phonological units. These units are called tones by convention. But they are complex templates, and they feel like the backbone of syllables. This is unlike Mazatec, where tone is just a pitch level, and is only one phonological ingredient among others.

Crucially, the object of the present study (Kim Thuong Muong) appears to fall squarely among the phonetically complex tone systems (like various other tonal languages of mainland Southeast Asia), since one of its tones has glottalization (canonically realized as creak).

In this perspective, a question comes into sharp focus: what is the phonological status of creak in Muong? Muong only has one glottalized (creaky) tone. That tone is also the lowest tone within the system. It reminds one of Tone 3 in Mandarin, which is the lowest tone and reported to be creaky. Kuang (2017) concludes that "creaky voice in Tone 3 is phonetically just a by-product of laryngeal adjustment for producing phonological low pitch". The role of creak is marginal in another well-studied Sinitic language: Cantonese [START_REF] Yu | The role of creaky voice in Cantonese tonal perception[END_REF], which is closer to Muong both geographically and in some phonological respects (such as the number of tones and the existence of stop-final syllables). From this perspective, it could seem perfectly reasonable to expect Muong to pattern in a similar way to these two Asian languages. Therefore, for the purpose of this study, we raise two main research questions, which are:

• What is the role of creaky voice in Kim Thuong Muong? How does it combine with pitch to compose the tone system? • To what extent is there variation in the glottalized tone? An attempt is made to prove the phonological status of creaky voice as part of the glottalized tone. Through experience with the dialect prior to the experimental study reported here, my initial hypothesis was that Muong should be classified in the same set as Vietnamese in terms of the use of glottalization as a dimension of the tone system alongside pitch. But Muong is saliently different from Vietnamese in using creaky voice as a distinctive phonation type: the phonetic realization of the creaky tone in Muong is thereby unlike that of the glottalized Vietnamese tones (etymological B2 and C2), which have glottal constriction as their canonical realization.

Such is the research project carried out in the following chapters.

Chapter 2

Background

This chapter sets out background knowledge: information that needs to be referred to later on in the study. It includes a section setting out a theoretical framework for the study of prosody, intonation and tones, a review about linguistic uses of phonation types, and general information about the target language, Kim Thuong Muong.

Prosody, intonation and tone: a framework

Intonation studies currently find themselves in a paradoxical situation: the number of published works is growing steadily, but we remain far from a consensus even on the most elementary points of method, starting with the very definition of what constitutes intonation. 1 The lack of consensus is an issue for beginners entering this field of studies. It warrants taking the time to set out at some length the general framework adopted here for the study of prosody, intonation and tone. 2 A guiding thread along this path consists in taking into account information concerning the intonation of languages which have lexical (sometimes also grammatical) tones: such is what is meant here by tone languages. Tone languages arguably offer a privileged angle of approach to establish certain fundamental conceptual distinctions, and to maintain them consistently.

Phonetics, phonology and intonation

What is intonation? The field as a whole remains marked by a diversity of apparently irreconcilable points of view, from which there stem many misunderstandings. In his book entitled Intonation, Cruttenden starts out by delineating a suprasegmental or prosodic domain by contrasting it (quite classically) with the segmental domain: that of phonemes. Thus, the adjective nice has three phonemes: a nasal consonant /n/, a diphthong /aɪ/, and a fricative /s/. Such is its segmental composition: /naɪs/.

But there are clearly other features involved in the way a word is said which are not indicated in a segmental transcription. The word nice might be said softly or loudly; it might be said with a pitch pattern which starts high and ends low, or with one which begins low and ends high; it might be said with a voice quality which is especially creaky or especially breathy. Such features generally extend over stretches of utterances longer than just one sound and are hence often referred to as suprasegmentals (…). Alternatively, the shorter term pRosodic is sometimes used and I shall generally prefer this term in this book. (Cruttenden, 1986, p. 1) Thus far, intonation is not mentioned. It appears in the next sentence, but fairly indirectly, as part of a passage tacked on inside brackets.

Prosodic features may extend over varying domains: sometimes over relatively short stretches of utterances, like one syllable or one morpheme or one word (…); sometimes over relatively longer stretches of utterances, like one phrase, or one clause, or one sentence (intonation is generally relatable to such longer domains). (ibid.)

It seemed necessary to quote these passages in full to bring out a paradoxical observation: intonation is not defined at the outset of the book (entitled Intonation), as if the meaning of the word were self-evident. Cruttenden contrasts the segmental dimension of an utterance (its consonants and vowels) with its suprasegmental dimension, which is understood to possess structure: use of the phrase "prosodic features" implies that prosody comprises an organization based on discrete units, namely features, a fundamental concept in classical phonology. Within the domain of prosodic features, one gathers that only some have intonational value. Readers of Cruttenden's textbook are left to clarify for themselves, as best they can, what the term intonation covers. Are we to understand that intonation is an abstract linguistic structure, which concerns non-segmental units?

In an encyclopedia article by the same name ("intonation"), Francis Nolan provides a more explicit characterization.

The term intonation refers to a means for conveying information in speech which is independent of the words and their sounds. Central to intonation is the modulation of pitch, and intonation is often thought of as the use of pitch over the domain of the utterance. However, the patterning of pitch in speech is so closely bound to patterns of timing and loudness, and sometimes voice quality, that we cannot consider pitch in isolation from these other dimensions. (…) For those who prefer to reserve 'intonation' for pitch effects in speech, the word 'prosody' is convenient as a more general term to include patterns of pitch, timing, loudness, and (sometimes) voice quality. (Nolan, 2006, p. 433) Nolan takes up the negative characterization of intonation (as being independent of phonemes) but enriches it by an important observation concerning the level of the word. To say that intonation is "independent of the words and their sounds" is to clarify that intonation is placed above the level of the word, and thus above lexical phenomena such as stress (in a language like English or German) and tones (in languages like Bambara, Mandarin, Vietnamese, Muong and many more). However, intonation is not explicitly characterized by F. Nolan as an abstract structure. The characterization that he provides suggests that intonation is essentially a matter of the use, in spoken communication, of three acoustic parameters: fundamental frequency (f 0 , and its perceptual counterpart: pitch), intensity and duration. Feeling confident about the merits of a method that had been tried and tested successfully in the "segmental" domain, linguists have attempted to approach intonation as a topic of phonology. Their ambition is to uncover, below the endless variation of phonetic substance, a structure characterized by discrete (categorical) oppositions and by identifiable principles of organization. Readings about intonation typically deal with the phonology of intonation, or intonational phonology [START_REF] Gussenhoven | Phonology of intonation[END_REF][START_REF] Jun | Prosodic typology[END_REF]Ladd, 2008). The phonetician-phonologist shoulders the full burden of clarifying "what intonation consists of, and how we can visualize it and analyze it phonologically" (Nolan, 2006, p. 434).

On the face of it, the approach which consists in progressing from experimental phonetics to phonological modeling conforms to the requirements of the scientific method. It is rooted in the empirical observation of phonetic phenomena (in particular the analysis of fundamental frequency curves), and guided by ambitious goals in terms of theoretical modeling. However, there are signs that suggest that intonation studies carried out according to phonetic-phonological methods are up against limitations, which the authors foresee to some extent. An example of this can arguably be drawn from a reflection by David Crystal according to which "intonation is not a single system of contours and levels, but the product of the interaction of features from different prosodic systems -tone, pitch-range, loudness, rhythmicality and tempo in particular" (Crystal, 1975, p. 11). Crystal's reflection points to the need to look beyond a conception of intonation that would reduce it to issues of melody: contours (rises and falls) and levels (on a pitch scale). To evoke "different prosodic systems" is to open the door to the recognition of various dimensions of intonation, each of which could be approached with specific methods. But the opening thus achieved is immediately closed down again by offering a list that is limited to the familiar phonetic dimensions, commonly called "suprasegmental", as they also appeared in Francis Nolan's characterization of intonation quoted above: f 0 , intensity and duration. These three parameters appear in a list that is admittedly intended to be open ("in particular…"), but which in practice amounts to foregrounding these three specific phonetic dimensions -as is natural enough for a phonetic-phonological study. After one has entertained high hopes of holding intonation under our gaze (to repeat F. Nolan's formula quoted above: "how we can visualize it and analyze it phonologically"), it is difficult to give up hopes of near-immediate access and to enter a long detour through other dimensions of linguistic complexity: dimensions that are neither phonetic nor phonological. Such a research program is all the more unattractive as the intonation of English -the most widely taught language worldwide, and consequently the most studied by linguists -can be adequately described (better than that of many other languages) in terms of patterns of fundamental frequency alone: the patterns that are referred to as "tones" in the British school of intonation studies [START_REF] O'connor | Intonation of colloquial English[END_REF].

Seasoned practitioners of language description point out, however, that the task of studying intonation is not a straightforward one. Intonation "has considerable importance in oral communication, but has specificities that make it really troublesome to the linguist, since the methods that have been tried and tested in other areas do not seem truly adequate for the analysis of intonation" (Creissels, 1994, p. 173). Is the phonetician-phonologist well equipped to deal with intonation? The question may come as a surprise, since the association between intonation (whose links with oral speech are self-evident) and phonetics-phonology seems obvious. However, to venture a critical reflection about the field of phonetics/phonology at large, the emphasis on the sounds of speech tends to place the researcher in the position of an outside observer. It can have the effect of exempting him or her from confronting languages as instruments of communication. It is quite possible to carry out an experimental phonetic analysis of a given phonological opposition without speaking the language at issue. Among linguists, phoneticians/phonologists are not necessarily General Practitioners of linguistic analysis: they are not necessarily the best connoisseurs of the functioning of languages in the diversity of their dimensions. Seen in this light, entrusting phonologists with the task of clarifying the functioning of intonation looks like a paradox, as the study of this domain requires paying attention to communicative dimensions that are not exclusively (or even primarily) phonetic-phonological.

To progress in the understanding of intonation, it therefore appears promising to adopt a functional characterization, rather than a phonetic-phonological characterization. The definition of intonation adopted here is that elaborated by Mario Rossi, and adopted by Jacqueline Vaissière and Alexis Michaud (with minor adaptations, explained below). Rossi's definition is not based on phonetic properties (physiological, articulatory, acoustic or perceptual).

Intonation, which has long been confused with one of its privileged parameters, melody, is a linguistic system designed to organize and prioritize the information that the speaker intends to communicate to the addressee(s) in his message, and to linearize the hierarchy of syntactic structures. [START_REF] Rossi | L'intonation[END_REF].

In the study of intonation, it appears as a good method to start from a characterization that is placed at this level of abstraction: that of the linguistic system.

Rossi distinguishes several strands in the understanding of the term intonation. Understanding intonation as a melody leads to a single-parameter approach (focusing on fundamental frequency), and to an interpretation in terms of phonological units. In the autosegmental-metric theory, these units are H (High) and L (Low) levels, which appear on a line (tier) distinct from the segmental line. Rossi's approach stands in strong contrast to the single-parameter approach, as it recognizes several components within intonation: "intonation is a part of prosody; prosody comprises accentuation, intonation and rhythm" (Rossi, 2001, p. 103).

Accentuation here refers to lexical stress. This characterization is sufficient in the field of Romance languages (the primary object of Mario Rossi's study). On the other hand, from a typological perspective, it needs to be given a broader meaning to take into account other prosodic phenomena that affect the level of the lexical word, such as lexical tones. Insofar as they ensure lexical oppositions, these features meet the definition of the phoneme. Thus, some authors speak of tonemes to refer to lexical tones (Pike, 1948): the term has the advantage of linking up with the notion of allotones, variants of tone realization, parallel to allophones for segmental phonemes. Since the meaning of the concept of accentuation is thus broadened, it is appropriate to change the name as well. The term accentuation has a relationship with the notion of accent that no redefinition can effectively neutralize. For these lexically distinctive phonological entities, the name proposed is lexical prosodic properties. Also replacing rhythm with the more general term of performance factors, which includes rhythm, one arrives at the schema of prosodic components presented in Figure 2 With the above framework in mind, one is in a position to describe the relationships between tones and intonation without running into paradoxes.

Tones and intonation

Does the presence of lexical (or grammatical) tones imply that tonal languages are devoid of intonation? Clearly, the answer is no: tonal languages possess, in addition to tones, an intonation system of their own, so that it is not appropriate to distinguish "tone languages" and "intonation languages". This necessary clarification has been reiterated many times through the history of linguistic theories (see in particular Hockett 1963;[START_REF] Zerbian | Developments in the study of intonational typology[END_REF]. In contrast, a more persistent misconception is that intonation necessarily plays a lesser role in tonal languages. Lexical tone and intonation share certain acoustic correlates (in particular fundamental frequency), and this use of the same communication channels (to put it in an information-theoretic perspective) leads to the belief that the role of intonation in a tonal language is highly limited. This is the point of view expressed by Cruttenden, for example.

Tone and intonation are not completely mutually exclusive in languages. Languages with tonal contrasts may nevertheless make use of a limited amount of superimposed intonation. Such superimposed intonation may be manifested in four different ways: (i) the pitch level of the whole utterance may be raised or lowered; (ii) there will usually be downdrift in the absolute value of tones but downdrift may be suspended; (iii) the range of pitch used may be narrower or wider; (iv) the final tone of the utterance may be modified in various ways. (Cruttenden, 1986, p. 9) Just as phonetically very similar phenomena can correspond, at the functional level, to a lexical accent in one language, and to intonational (pragmatic) emphasis in another, so intonational and tonal phenomena would be, if not in a mutually exclusive relationship, at least in a situation of competition, with intonation as the weaker competitor (emphasis added: "… a limited amount of superimposed intonation"). This point of view, which remains widespread, does not do justice to the richness of intonational phenomena observed in tonal languages. It seems more forward-looking to point out that "tone languages can have all features that characterize intonation-only languages, but not vice versa" (Steien and Yakpo, 2020, p. 5). The simultaneous presence of tonal and intonational phenomena is described in several works, including [START_REF] Downing | Introduction[END_REF] for various African languages, [START_REF] Vydrina | A corpus-based description of Kakabe, a Western Mande language: prosody in grammar[END_REF] for Kakabe (Mande group), and Michaud and Vaissière (2015) for some Asian languages. Without trying to summarize the literature, it seems worth highlighting the diversity of ways in which intonation and tone can coexist.

One such possible way is mutual avoidance. This is how [START_REF] Pittayaporn | Prosody of final particles in Thai: Interaction between lexical tones and intonation[END_REF] describes the situation of final particles in Thai, some of which have a lexical tone, others not. In his comparative study of the two categories of final particles, Pittayaporn suggests that intonation (described in terms of "boundary tones", but functionally located on a different plane than lexical tones) is freely manifested on particles without tonal specification, whereas it is entirely neutralized in the case of particles with tonal specification. More complex modalities of coexistence were already identified by [START_REF] Luksaneeyanawin | Influences of speaker attitudes on glottalized tones: a study of two Vietnamese sentence-final particles[END_REF], however. Various attitudes (assertion versus questioning, doubt, disbelief or surprise, for example) translate into global or semi-global patterns of fundamental frequency, on which lexical tones are superimposed. The phonetic literature on intonational cues conveyed by phonetic detail in the realization of vowels and consonants at a given point in the utterance [START_REF] Fougeron | Prosodically conditioned articulatory variations: A review[END_REF][START_REF] Kohler | On the role of articulatory prosodies in German message decoding[END_REF][START_REF] Niebuhr | The acoustic complexity of intonation[END_REF] highlights the diversity of prosodic cues, and hence the way in which tones and intonation pass simultaneously through channels that are certainly (in part) common, but diverse enough to circulate a wealth of information.

In light of the above clarifications, the topic of phonation types (specifically: glottalization) in relationship to tones and intonation can now be addressed.

Linguistic uses of phonation types

Below, a sample of publications about tone and phonation is reviewed in order to set the stage, without aiming at comprehensiveness: tones and phonation types would warrant a full Encyclopedia by themselves. The main goal here is functional: to shed light on the full range of terms used in the present study, so as to avoid (or at least limit) ambiguities and possible misunderstandings.

Phonetically, glottal stops occur in many languages, including English [START_REF] Christophersen | The glottal stop in English[END_REF], French Malécot, 1975and German Kohler, 1994. In British English, 'glottaling' of consonants (especially /t/) is common [START_REF] Przedlacka | Estuary English: glottaling in the Home Counties[END_REF]. In many languages, glottal stop serves as an empty-onset filler: e.g. in French, empty-onset words that have little phonological material tend to be reinforced (set apart from the preceding words) by an initial glottal stop, as in je m'appelle Yves, which tends to be realized as /ʒmapɛlʔiv/ rather than /ʒmapɛliv/, or je m'appelle Anne, which tends to be realized as /ʒmapɛlʔan/ rather than /ʒmapɛlan/ (this observation was communicated by Michel Launey to Alexis Michaud).

Phonemic use of glottalization (glottal constriction or creaky voice) is relatively uncommon cross-linguistically. P. Ladefoged and Maddieson (1996, p. 48) mention phonation types as part of their discussion of stop consonants; the examples that they mention of languages making use of creaky voice in association to stops are Hausa and Mazatec. Another example is Hayu [START_REF] Michailovsky | La langue hayu[END_REF]. All three are likely to appear as highly "exotic" languages in the eyes of many phoneticians.

Phonation-type registers

Phonation-type registers are widespread in Southeast Asia, where they constitute a key topic in diachrony as well as in synchrony. However, they are reported to be fairly rare among the world's languages at large. As a result, phonation-type registers may be unfamiliar to some readers, including persons with a thorough and well-rounded training in general linguistics. An introduction to this topic is therefore proposed below. It constitutes a digest of published materials; readers who are already familiar with the topic can safely skip this brief review, as well as the next, which goes into the topic of ways in which phonation types can be compounded with tones.

Register is a common phonological contrast in the Austroasiatic and Chamic languages of Mainland Southeast Asia [START_REF] Henderson | The main features of Cambodian pronunciation[END_REF]Haudricourt, 1965;Gregerson, 1976;Huffman, 1976;[START_REF] Ferlus | Formation des registres et mutations consonantiques dans les langues mon-khmer[END_REF]. It consists in a bundle of acoustic properties -the most important being f 0 , phonation type, and vowel quality -that are realized on rhymes but originate from a voicing contrast in onsets (no voicing contrast in sonorants is reconstructed in Proto-Austroasiatic and Proto-Chamic). The low register (also second or lax register) derives from former voiced stops, while the high register (also first or tense register) stems from original voiceless stops. Low register syllables typically have a lower f 0 and a laxer/breathier phonation and they often have more close vowels (or vowels with close onglides). Note that register languages do not necessarily combine all of these properties, and that others, like VOT [Voice Onset Time] and vowel duration, are often associated with the contrast. This characterization of register, summarized in Table 1, is supported by acoustic evidence from Austroasiatic (Lee, 1983;L.Thongkum, 1987L.Thongkum, , 1989L.Thongkum, , 1991;;Wayland, 1997;Watkins, 2002;Wayland & Jongman, 2003;Abramson, Luangthongkum, & Nye, 2004;[START_REF] Abramson | Voice register in Khmu: Experiments in production and perception[END_REF][START_REF] Dicanio | The phonetics of register in Takhian Thong Chong[END_REF]Abramson, Tiede, & Luangthongkum, 2015;Tạ, Brunelle, & Nguyễn, 2019) and Austronesian languages (Fagan, 1988;Edmondson & Gregerson, 1993;Hayward, 1995;Thurgood, 2004;Brunelle, 2005Brunelle, , 2009aBrunelle, , 2010;;Matthews, 2015). [START_REF] Brunelle | Transphonologization of voicing in Chru: Studies in production and perception[END_REF] The literature review in DiCanio's audio and electroglottographic study of Chong, a language of Cambodia [START_REF] Dicanio | The phonetics of register in Takhian Thong Chong[END_REF], offers a clear and handy introduction to the typological diversity of phonation-type registers.

Most register languages contrast only two phonation types, e.g. Middle-Khmer (Jacob 1968) andWa (Watkins 2002). Those which contrast three are quite rare, but do exist, e.g. Jalapa Mazatec [START_REF] Kirk | Quantifying acoustic properties of modal, breathy and creaky vowels in Jalapa Mazatec[END_REF]) and Bai (Edmondson & Esling 2006), and, of course, languages with a four-way phonation-type contrast are extremely rare. Only a few languages in the world have been found to use this number of contrasts: Chong (Thongkum 1991), !Xóõ (Traill 1985), Bai, andBor Dinka (Edmondson &Esling 2006). Chong contains both dynamic (contour) and level registers. There is a modal register, a tense register, a breathy register, and a breathy-tense register.

Beyond the complexities of combinations among phonation-type registers, as explored by DiCanio, a topic of special interest, which stands at the heart of the present work, is the association of phonation types with tones.

Phonation types and tones: typological observations

From a general linguistic point of view, there are interesting synchronic and diachronic ties between phonation types and tones. Phonation types arguably play a role in some tonogenetic processes. In the case of Vietic, the diachronic links between glottal stop (or glottal constriction) and tone are well-established (Ferlus, 2004). In languages of Europe, too, glottalization in a dialect can correspond regularly to tone in another.

Remarkably, the relation between tone contours in the north [of the Scottish Gaelic area] and glottalization in the south has an exact parallel in Scandinavian as well. Glottalization in Danish (the so-called stød) corresponds to word tone in Norwegian and Swedish in the following way: glottalization corresponds to tone 1, absence of glottalization corresponds to tone 2. (Ternes, 2006, p. 143) Synchronically, even though each phonation type has natural association to a certain range of f 0 (typically: low f 0 and creaky voice), different languages clearly use different combinations of pitch and phonation types for tonal contrasts. An instance of synchronic combination between pitch and phonation type to produce tonal contrasts is found in Qingjiang Miao (Ch'ing Chiang Miao), a Black Miao dialect belonging to the Hmong-Mien (Miao-Yao) family. This language has five level tones, among a total of eight tones (the remaining consist of two rising and one falling). Phonation cues contribute to a comfortable auditory distance between the tones (Kuang, 2013b;Kuang, 2013a). In other words, the combination between pitch and phonation-type characteristics allows for well-dispersed tonal spaces (note that the term "tonal spaces" is used here in an abstract phonological sense, obviously not restricted to pitch).

Within the large and diverse landscape of phonation types and tones, there are several reasons that make a close look at Hanoi Vietnamese especially relevant as a preparation to the study of Muong.

Phonation types and tones: Hanoi Vietnamese as a textbook example

A look at Hanoi Vietnamese can serve as a handy introduction for readers with less familiarity with prosodic systems that use glottalization as part of lexical tones. There exists a relatively abundant literature covering the topics of the templates of the lexical tones as realized in isolation or in carrier sentences (T.-L. [START_REF] Nguyen | The interplay of intonation and complex lexical tones: how speaker attitudes affect the realization of glottalization on Vietnamese sentence-final particles[END_REF], tonal coarticulation [START_REF] Han | Phonetic variation of Vietnamese tones in disyllabic utterances[END_REF], and topics of intonation [START_REF] Brunelle | Intonation in Northern Vietnamese[END_REF]. Studies of Vietnamese tone set high standards for studies of tone in Muong, which should aim to vie with these achievements.

As an illustration of the acoustic outlook of glottalization, instead of taking up information from one of the above studies, let us examine data recorded in the year 1900 by a native speaker from the Hanoi area. The recording was done at the Paris Exposition Universelle by Léon Azoulay, of the Paris Society for Anthropology (Société d'Anthropologie de Paris). 3 Use of these historical materials adds a special twist to the inherent interest of this tone system, and arguably allows for relevant methodological insights concerning data collection as well as the estimation of fundamental frequency. 4The recording includes the six tones of smooth syllables (syllables without a final stop consonant) as exemplified with the syllable cơ (IPA: /kɤ/).

Figure 2.2 shows tone ngang (etymological A1). Frequencies outside the range from 600 to 6,000 Hz are attenuated, presumably due to characteristics of the recording device, and do not show on the spectrogram at the chosen level of contrast (the dynamic range chosen for drawing the spectrogram is 40 dB). Also, there is noise in the range from 1,200 to 2,500 Hz, that likewise seems attributable to the recording device. It is Tone huyền (etymological A2), shown in Figure 2.3, is falling towards the end. Again, this is not a phonologically glottalized tone, and no glottalization is discernible in the phonetic realization of this token.

The items were originally recorded in the following order: ngang huyền nặng sắc hỏi ngã (etymological A1, A2, B2, B1, C1, C2). For the sake of clarity of exposure I shall nonetheless follow the etymological progression: A1, A2, B1, B2, C1, C2, and thus move on presently to tone B1 (Figure 2.4), tone sắc. It has a sustained phonetic rise, straightforwardly reflecting its characterization in the phonological literature as a rising tone.

Figure 2.5 shows tone B2, tone nặng, which is characterized by a strong final glottal constriction. This example introduces all at once several of the complexities associated with glottalization. The syllable shows strong changes in amplitude in the course of the vowel, pointing to glottalization in the first half of the syllable (contrary to the expectation that glottalization would be observed at the end of the syllable). Fundamental frequency then rises sharply, together with an increase in the signal's amplitude. Finally, f 0 decreases, perhaps with some final glottalization. To my ear, this token of tone B2 sounds closer to ngã (C2): in my dialect (standard Northern Vietnamese), a syllable with glottalization followed by a modal interval with higher pitch is categorized as ngã (C2), whereas tone nặng (B2) is associated to syllable-final glottalization. In cases where the glottalization of B2 is followed by a modal-voiced interval, its pitch must be low, otherwise the syllable will be categorized as carrying tone ngã (C2).

If I allow myself to speculate as to why the speaker produced such a realization: it could be that this was the usual realization in his speech; but it seems more likely to me that during the rehearsal of this recording, the investigator felt that the standard realization of this tone would not be loud enough for a good recording: the syllable, cut short by glottal constriction, tends to sound as if it were strangled. It might therefore be that an artefact crept in: that the person in charge of the recording instructed the consultant to produce a stronger realization, resulting in a token which is even more hyper-articulated than the other tones: a longer syllable, with more voicing after the glottalization than would usually be observed for this tone. The diversity of intonational variability of the tones serves as a word to the wise: special care is necessary at elicitation of glottalized tones.

The last two tones, C1 and C2, are shown in Figures 2.6 and 2.7 respectively. When comparing the pair formed by this speaker's B2 and C2 tones, the difference becomes aurally clear, because his tone C2 has noticeably higher overall pitch, and ends on a much higher pitch than C2.

This observation illustrates (i) the importance of the phasing of glottalization, and (ii) the phonetic relativity of the cues to tone, including phonation types. It calls for tools to describe these phenomena with high accuracy, to progress towards phonetic and phonological models that get as close as possible to these complex phenomena. In this endeavour, an important aspect is the exploratory technique used. Fundamental frequency detection as implemented in phonetic software packages such as PRaat can fail for glottalized portions, because the algorithms requires, if not quasi-periodicity in the signal, at least a degree of similarity between successive glottal cycles -a requirement which is often not met in audio signals corresponding to glottalized portions of speech, as exemplified by Figure 2.8a, also taken from the 1900 recording. The token is a realization of Vietnamese tone C2 (ngã) over the syllable /ɓa/.

If the "Advanced pitch setting" voicing threshold in PRaat is set at 0.7, spurious periods of high f 0 are detected (see Figure 2.8a). If this parameter is set at 0.8, these spurious periods disappear, but no f 0 is detected on the initial portion of the syllable either: see Figure 2.8b. Over one hundred years after this speech signal was recorded, there exists no simple way out of this technical difficulty. 5This last observation, which highlights the usefulness of exploratory techniques to complement audio recordings, provides a handy transition to the topic of electroglottography.

Definitions: glottalization and creaky voice

Uses of glottalization and creak range from the phonemic to the 'paralinguistic'.

… an American English speaker may have a very creaky voice quality similar to the one employed by speakers of Jalapa Mazatec to distinguish the word /já̤ / meaning 'he wears' from the word /já/ meaning 'tree' (Kirk, J. Ladefoged, and P. Ladefoged, 1993). As was noted some time ago, one person's voice disorder might be another person's phoneme (P. Ladefoged, 1983). (Gordon and P. Ladefoged, 2001, p. 383) The developments that precede -in particular the introductory note in 1.1, the review of linguistic uses of glottalization in §2.2, and the results in Chapter 4 -now place us in a position to put forward some definitions, and to progress towards a systematic characterization of glottalization in Kim Thuong Muong.

In this thesis, 'glottalization' is used as a cover term for glottal constriction, creaky voice, and all the phenomena that range in-between them. Inside the field of glottalization, a distinction is made between creak, on the one hand, and on the other hand glottal constriction and glottal stop -keeping in mind that there can be intermediate cases.

Literature review of creaky voice

The process of becoming an independent object of study in the field of voice quality

Today, creaky voice is a mainstream topic in phonetics/phonology and beyond, witness e.g. a review article bringing to the attention of cognitive scientists "[t]he versatility of creaky phonation: Segmental, prosodic, and sociolinguistic uses in the world's languages" [START_REF] Davidson | The versatility of creaky phonation: Segmental, prosodic, and sociolinguistic uses in the world's languages[END_REF]. That constitutes an ideal environment to carry out an in-depth monographic study like the present one. However, it may be worth highlighting that interest in creak as a topic of scholarly investigation is a relatively new development.

It is natural enough that it had earlier (say, until the first half of the twentieth century) been considered mostly in relation to pathology, rather than to linguistic (phonemic and intonational) uses. Creak does not have phonemic status in the languages with which the Association phonétique des professeurs de langues vivantes was primarily concerned. Hence its absence from the table of phonetic symbols in the initial set, published in their journal, Le Maître phonétique, and which eventually expanded into the International Phonetic Alphabet as we know it, complete with a special symbol for creaky voice. In fact, creaky voice was at first not distinguished from harshness, considered as a voice disorder (Michel, 1964, p. 2) or a laryngeal pathology [START_REF] Sherman | The influence of certain vowel types on degree of harsh voice quality[END_REF]. Paul [START_REF] Moore | Dynamic variations of the vibratory pattern in the normal larynx[END_REF] considered creak as "a peculiar voice quality" (p. 224) or even "a non-language sound" (p. 234). As noted by Peter Ladefoged in a famous quote:

What is phonemic in one language may be pathological in another. This is especially true with respect to voice quality. (P. Ladefoged, 1981) It seems that the limitations of the vision of creak as a speech defect were early realized by some authors. There were efforts to clarify subsets within the phenomena pooled together under the label of 'harshness', adding other technical terms -although these efforts did not go without their own risks of bringing up more ambiguity. [START_REF] Anderson | Training the speaking voice[END_REF] suggests several terms such as "breathiness, hoarseness, and huskiness, harshness and stridency, and throatiness" as labels for voice disorders. However, the boundaries among his categories are not crystal clear. He considers harsh as a partial description of huskiness and throatiness, while breathiness serves as one of the characteristics to describe hoarseness; I can see how these associations can match real examples, but would find it awkward to pin these together in hard-and-fast categories, as I would see no contradiction in different patterns, such as association of the notion of harshness with hoarseness. [START_REF] Van Riper | Voice and articulation[END_REF]Irwin (1958) (cited in Paul Moore andLeden 1958, p. 255) use both terms "harsh voice" and "strident voice" for the same voice quality; they firstly recognize "glottal fry" as a distinct component within "harsh" voice quality, but later on in the same paper they mention "glottal fry" as an equivalent to "hoarseness", which is treated apart from harshness and stridency. Paul [START_REF] Moore | Dynamic variations of the vibratory pattern in the normal larynx[END_REF] comments that there is "considerable ambiguity in the use of the terms. The semantic problems arise from the fact that various writers have employed one term to designate different qualities, and conversely, a variety of names have been applied to a single quality. "

A clear stride towards clarity of phonemic nomenclature is achieved when the perspective on creaky voice (vocal fry) changes from "an abnormal voice quality relating to harshness" to a normal function. A landmark here is arguably the publication of two studies: [START_REF] Wendahl | Comments on vocal fry[END_REF] and Hollien, P. Moore, et al. (1966, p. 246). They postulate that vocal fry exists as a "physiologically normal mode of laryngeal operation". They also suggest that vocal fry can be "best described as a phonational register occurring at frequencies below those of the modal register".

I hasten to add that the emphasis placed here on these two studies does not imply that there are no earlier published statements pointing in the same direction. [START_REF] Moser | Symposium on unique cases of speech disorders; presentation of a case[END_REF] and [START_REF] Van Riper | Voice and articulation[END_REF] "have alluded to the possibility that it may be a normal function" (Michel, 1964, p. 3). The idea here is that Hollien's work contains a cogent, articulate picture. Supporting Hollien's proposing, John Frederich Michel distinguishes creaky voice (called vocal fry at that time) from harshness in particular and from voice disorder in general. In his PhD thesis, Michel provides the following clarification: …the distinction must be made between clinical harshness and simulated harshness. The former may be characterized in terms of the Curtis definition and is typified by a functional or organic problem. Simulated harshness can be defined as a voice which is perceived to be rougher than normal but exhibits no pathology. Unfortunately, simulated harshness probably consists primarily of vocal fry. (Michel, 1964, p. 8) Later, more and more authors and articles supported this viewpoint, based on different dimensions and approaches.

Aerodynamics: [START_REF] Mcglone | Air flow during vocal fry phonation[END_REF], the first author who provided information about air flow during vocal fry phonation, agrees with Hollien, P. [START_REF] Hollien | On the nature of vocal fry[END_REF] that "this phonation involves a physiologically normal mode of laryngeal operation which results in a distinctive acoustic signal".

Production: [START_REF] Hollien | Vocal fry as a phonational register[END_REF] explores further the possibility that vocal fry is a separate phonational register from modal voice and falsetto. A broad data set is used: materials from 12 males and 11 females. "The results provide data that demonstrate vocal fry to be a register as specified" (Hollien and Michel, 1968, p. 600).

Perception: In the same year, Hollien collaborated with Wendahl to conduct a perceptual study of vocal fry. The result showed that "repetition rate can be successfully assigned to vocal fry. In addition, evidence was obtained indicating that vocal fry occurs within a low-frequency phonatory register, is perceived similarly in relation to single or double glottis pulses, and is regular, rather than aperiodic, in nature" (Hollien and Ronald W. Wendahl, 1968, p. 506). In this paper, in an attempt to separate the relationship between vocal fry and voice disorders, they make the following claim:

In the past, vocal fry has often been equated with rough or harsh voice quality. Recently, however, harshness and hoarseness have been associated with irregular vibrations of the vocal folds, the presence of aperiodicity in the signal, or a range of frequencies falling within the modal register. Thus, the low frequency and the perceptual regularity of vocal fry found in this study provide evidence against classifying it among the voice pathologies. (Hollien and Ronald W. Wendahl, 1968, p. 509).

This long citation clarifies that they only recognize vocal fry with regular single or double pulses (the case of triple pulses is also reported but quite rare) as a normal mode of laryngeal production. Aperiodicity is still set on the side of voice disorder: this is used as a criterion for distinguishing fry from harshness. This criterion was subsequently challenged, however, as linguistic studies pointed to numerous cases where aperiodicity is among phonetic sub-types of creak [START_REF] Redi | Variation in the realization of glottalization in normal speakers[END_REF][START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]. In the same year, Michel explicitly proposed to base the fundamental distinction between vocal fry and harshness, not on the presence or absence of aperiodicity, but simply on fundamental frequency. He reported that: "A mean fundamental frequency of 36.4 Hz with a range of 30.9 to 43.7 Hz was found for vocal fry; the mean of the harsh voices was 122.1 Hz within a range of 103.7 to 180.0 Hz" (Michel, 1968, p. 590).

Of course, using f 0 as a criterion requires that this parameter be measurable in the first place, and thus, that there be some kind of periodicity (cyclicity) in glottal behavior, thereby making it possible to exclude (or give separate treatment to) cases of wild aperiodicity. Not all instances of creaky voice are content with a neat phonetic corridor of low fundamental frequency such as reported in the above quotation, where the creaky voice is so well-behaved that the investigator ventures to describe it with a precision of less than 1 Hz ("30.9 to 43.7 Hz"). This quibble apart, the shift in emphasis away from periodicity as such appears well-warranted from a linguistic perspective. [START_REF] Laver | The phonetic description of voice quality[END_REF] agrees with Michel: "The low fundamental frequency of this creak type of phonation is one factor that distinguishes it from harsh voice, which is otherwise somewhat similar". The present study is among those that gratefully take up the usage thus clarified.

Physiology: Using ultraslow motion pictures, [START_REF] Timcke | Laryngeal vibrations: Measurements of the glottic wave: part ii. physiologic variations[END_REF] are probably the first authors who explored the physiological mode of laryngeal operation that leads to perception of creaky voice. One of the most typical characteristics that must be met for its perception is a train of discrete excitations or pulses. This characteristic has been explained by a "nearly complete damping of the vocal tract between successive excitations". The "double glottis pulse" has been described as a unique vibratory pattern in which "the vocal folds opened and closed twice (per cycle) in rapid succession and then remained closed for relatively long periods of time" [START_REF] Hollien | Perceptual study of vocal fry[END_REF].

Nowadays, after more than 60 years of experimental studies of creaky voice, Hollien's statement (already cited above) that this voice quality "is best described as a phonational register occurring at frequencies below those of the modal register" (Hollien, P. Moore, et al., 1966, p. 246) is uncontroversially acknowledged. However, there is still a margin for progress in terms of concepts and terminology, and a need for clarification concerning the choices made in the present study among competing nomenclatures.

Creaky voice: nomenclature and sub-classification

The large terminological diversity for glottalization and creaky voice may be to some extent inherited from its relatively long history of nonstandardized nomenclature, prior to the clarifications recapitulated above. Creak has been identified in the literature under many different names, and this voice quality remains characterized by complex terminology. Before it came to be distinguished from harshness in the classifications of voice disorders, it was included under categories such as X-factor, Dysphonia ventricularis (cited in Paul Moore and Leden 1958, p. 235), Harshness or Harsh voice [START_REF] Van Riper | Voice and articulation[END_REF]Bowler, 1964), Strident voice (Van Riper and[START_REF] Van Riper | Voice and articulation[END_REF], Dicrotic dysphonia, and Glottal Fry (Paul [START_REF] Moore | Dynamic variations of the vibratory pattern in the normal larynx[END_REF]. Commenting on this unclear nomenclature and the "considerable ambiguity in the use of the terms", Moore and Leden suggest that: "The semantic problems arise from the fact that various writers have employed one term to designate different qualities, and conversely, a variety of names have been applied to a single quality" (Paul Moore and Leden, 1958, p. 225).

The specific voice quality has had limited identification in the literature under such names as glottal fry, x-factor, harshness (restricted definition), and dysphonia ventricularis. The specific quality is usually not recognized as a distinct entity in the literature and, therefore, is obscured in such term as harshness or hoarseness. The general result is a confused terminology. (Paul Moore and Leden, 1958, p. 235) Pertaining to "Dicrotic dysphonia": Some others believe this is an ideal term for this voice quality because it identifies the primary acoustic factors and associates them with the basic laryngeal physiology (…); "dicrotic dysphonia" refers to a faulty vocal sound produced by a vibratory pattern containing a double pulsation. (Paul Moore and Leden, 1958, p. 231) Once it is recognized that the phenomenon at issue is a normal human phonational register, it is more consistent with names such as vocal fry (R. W. Wendahl, G. P. [START_REF] Wendahl | Comments on vocal fry[END_REF][START_REF] Coleman | Decay characteristics of vocal fry[END_REF][START_REF] Michel | Vocal fry and harshness[END_REF][START_REF] Mcglone | Air flow during vocal fry phonation[END_REF] and creaky voice [START_REF] Laver | The phonetic description of voice quality[END_REF]P. Ladefoged and Maddieson, 1996;[START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]Kuang, 2017). No conceptual difference is made here between the labels 'vocal fry' and 'creaky voice'. These pairs of terms have been used somewhat confusingly, and it seems best not to try to attach specific meanings to each term. (P. Ladefoged and Maddieson, 1996, pp. 50-53) A further clarification concerns the terms 'laryngealized' and 'laryngealization'. Equivalence between 'creaky' and 'laryngealized' is widespread in linguistic usage. It is advocated by P. [START_REF] Ladefoged | The Sounds of the World's Languages[END_REF], and taken up e.g. in D. Crystal's Dictionary of Linguistics and Phonetics, where 'creak' is defined as follows:

A term used in the phonetic classification of voice quality, on the basis of articulatory and auditory phonetic criteria. It refers to a vocal effect produced by a very slow vibration of only one end of the vocal folds; also known as vocal fry. … Creaky sounds are also called 'laryngealized'. (Crystal, 2011, pp. 121-122) Some authors nonetheless reserve the terms 'laryngealized' and 'laryngealization' for a specific usage, e.g. as a cover term for creak and glottal constriction (as I did in my M. A. thesis, following Michaud 2004b). But in practice, the usefulness of such a cover terms appears somewhat limited, whereas the decision to redefine such a familiar term, whose diversity of usages remains strong, would place a burden on readers. The terms 'laryngealized' and 'laryngealization' are therefore avoided in this thesis, for the sake of legibility (the same reason why acronyms are avoided to the greatest possible extent).

Once the term 'creaky voice' is unambiguously adopted, there remains the topic of sub-classifications within creaky voice, as well as the topic of the overall nomenclature within which creaky voice is included, and which lends it its structural meaning.

It seems that, in the historical development of phonation type nomenclatures, there were initially no further distinctions: no taxonomy for sub-types within creaky voice, even though various authors recognized the existence of at least two kinds of creak (namely, single and double glottis pulses). Hollien described the two patterns as a unique vibratory mode. A perception test carried out on single and double pulses led to the conclusion that: "The number of pulses produced is immaterial to the perception of phonation as vocal fry" (Hollien and Ronald W. Wendahl, 1968, p. 509). This was clearly a strong reason not to enter into sub-classifications of creak at that time. Proposals for sub-classification of creaky voice apparently date back to the 1990s, with the studies of [START_REF] Hedelin | Pitch period determination of aperiodic speech signals[END_REF], [START_REF] Batliner | MÜSLI: A Classification Scheme For Laryngealizations[END_REF], [START_REF] Gerratt | Toward a taxonomy of nonmodal phonation[END_REF], [START_REF] Redi | Variation in the realization of glottalization in normal speakers[END_REF], and [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]. Let us proceed to review them in some detail. [START_REF] Hedelin | Pitch period determination of aperiodic speech signals[END_REF] use a study of Swedish intonation as a basis to suggest a distinction between four different patterns of aperiodic glottal excitation, observed to occur consistently at different kinds of text junctures. These are: glottalization, creak, creaky voice and diplophonic phonation. Their acoustic patterns are illustrated by Figure 2.9 (reproduced from Hedelin and Huber 1990, p. 361). "Laryngealization" is used as a cover term for the four types mentioned above. This is consistent with [START_REF] Batliner | MÜSLI: A Classification Scheme For Laryngealizations[END_REF] but conflicts with P. [START_REF] Ladefoged | The Sounds of the World's Languages[END_REF] who used the term laryngealization as interchangeable with creaky voice. In this classification, creak is even distinguished from creaky voice. The term creak refer to a pattern of low frequency (in the range between 20 Hz and 50 Hz) and strong damping of vocal tract between successive excitations. "Alternative names often used in the literature for this pattern of glottal excitation include vocal fry, pulse register and strohbass. " Whereas creaky voice is characterized by "aperiodicity and fluctuations in intensity". The third type is diplophonic phonation which is characterized by "an alternation between strong and weak glottal excitations during phonation". Therefore, it correspond to the pattern of double glottis pulses as explored by previous studies. Figure 2.9: Acoustic patterns of four aperiodic glottal vibration. Reproduced from Hedelin and Huber (1990, p. 361). (1993).

As just mentioned, [START_REF] Batliner | MÜSLI: A Classification Scheme For Laryngealizations[END_REF] agree with Hedelin and Huber (1990) in using "laryngealization" as a cover term for all phenomena of the voice quality under discussion. They use six acoustic properties to distinguish six different types of "laryngealization" as reproduced in Figure 2.10, but their brief report provides little discussion and in my experience it is exceptionally difficult to follow. The summary attempted in Table 2.13 is mainly based on the similarity of the acoustic signals with those in other studies.

There is a conflicting use of terms between [START_REF] Redi | Variation in the realization of glottalization in normal speakers[END_REF] and the two works just mentioned above. Whereas [START_REF] Hedelin | Pitch period determination of aperiodic speech signals[END_REF] and [START_REF] Batliner | MÜSLI: A Classification Scheme For Laryngealizations[END_REF] classify glottalization as a sub-type within laryngealization, beside other sub-types of creakiness, [START_REF] Redi | Variation in the realization of glottalization in normal speakers[END_REF] use the term glottalization as a cover term for four sub-type of creak:

1. aperiodicity: irregularity in duration of glottal pulses from period to period; 2. creak: lowering of fundamental frequency with near-total damping; 3. diplophonia: regular alternation in the shape, amplitude, or duration of successive periods; 4. glottal squeak: a sudden shift to relatively high sustained f 0 , with a signal that usually has very low amplitude. A widely cited article about the classification of creak is [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]. In this paper, they set out a "prototypical creaky voice" as a standard pattern with three key properties: (i) low f 0 ; (ii) irregular f 0 ; and (iii) constricted glottis: a small peak glottal opening, long closed phase, and low glottal airflow. Then, "each of the three properties of prototypical creak can be lacking, yielding several further kinds of creak". They provided a table to illustrate the five different kinds of creak with their own set of characteristics (as reproduced in Figure 2.12). Among them, tense or pressed voice is not considered as a type of creak but "can function phonologically as such in languages in which a creaky (or laryngealized) phonation can co-occur with high tone". Different classifications found in the literature are summarized in Table 2.13, where I attempt to connect terms that appear (at least roughly) equivalent from among terminologies used by different authors. This classification is approximative and relative, because not only do the labels differ across authors, but the conceptual boundaries that they draw inside the landscape of phonation types also differ. Different authors use the same term for what others consider different contents, and different terms for what others consider as the same contents. Therefore, it is often unclear to what extent the terms that seem equivalent actually coincide in their intended extension. This topic will be taken up in the Discussion chapter ( §5.2), where a working nomenclature will be proposed.

Creaky voice and laryngealization

Auditory criteria indeed seem to be central to the notion of 'creak', since the term itself refers to an auditory impression. But paradoxically, it seems that phonetic studies of creak focus mostly on production and acoustics. This is a point that I would be interested to investigate further in future: the perceptual counterpart of different types of creak, and how perceptual data can help us find out more about which aspects of the acoustic signal are most relevant to the language users' perception. Now coming to more technical phonetic description, Patricia Keating, Marc Garellek and Jody Kreiman propose on the basis of a review of the literature that prototypical creaky voice has three key properties:

(1) low rate of vocal fold vibration (f 0 ), (2) irregular f 0 , and (3) constricted glottis: a small peak glottal opening, long closed phase, and low glottal airflow. [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF] In detail, the articulatory and acoustic part of the story is not tidy, and departure from canonical realizations are numerous. The list of articulatory and acoustic correlates of creak put together in a recent review is impressive: [START_REF] Laver | The phonetic description of voice quality[END_REF] mentioned] low subglottal pressure and glottal flow, slack, thick, compressed vocal folds with a short vibrating length, ventricular contact with the folds, weak or damped pulses, low f 0 , irregular f 0 , period-doubled vibration. Later descriptions (e.g. Childers and C. Lee (1991), [START_REF] Gobl | Voice Source Variation and Its Communicative Functions[END_REF], and D. Klatt and L. Klatt (1990)) added such properties as irregular amplitude, low Open Quotient, skewed glottal pulses, narrow formant bandwidths and sharp harmonics, abrupt closure of the folds, and low spectral tilt. [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF] Figure 2.12: The sub-classification of creaky voice by [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]. Reproduced from Keating, Garellek, and Kreiman (2015, pp. 1-3). Given this situation, it may appear necessary to phoneticians to confront the diversity headlong, and propose a phonetic categorization, together with recommendations on tools to tell apart the different categories. Building on earlier three-or four-way classifications of creaky voice into different types, Keating et al. propose a classification of the considerable diversity of phonetic realizations of creaky voice into five kinds. Not all of these five types have the characteristics of prototypical creak. This is a phonetic classification intended to help researchers choose acoustic measurement tools that are appropriate for the kind of creak that they aim to capture; this is not a classification primarily based on the linguistic functions of creak.

• Vocal fry: "Creak that is vocal fry with a regular f 0 could instead show higher HNR [Harmonics-to-Noise Ratio] together with lower formant bandwidths. " • Multiply pulsed voice: "Creak that is multiply pulsed can lack a clear f 0 but instead show sub-harmonics (resulting in higher values of SHR). " • Aperiodic voice: Creak that lacks the prototypical property of low f 0 ; instead, its properties are low H1-H2 and irregular f 0 . • Nonconstricted creak: "Creak can instead show higher H1-H2, but still with a low and irregular f 0 . " • Tense/pressed voice: "Creak that is more like tense or pressed voice can have a mid or high, and regular, f 0 . " [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF] The acoustic correlates of these five types are summarized in table form in Figure 2.12 of Chapter 2.

Glottal constriction and glottal stop

An overview of definitions is proposed by John Esling, placing the term 'glottal stop' in historical perspective. It seems well worth copying the entire passage in full, because it not only recapitulates a long historical line of proposed definitions, but highlights directions for fresh work taking into account the full physiological complexity of the larynx and more generally of what he names the "valves of the throat".

In the phonetic literature, there is a long but not always consistent history of the definition of glottal stops. Holder (1669, pp. 60, 72) defined a glottal stop as ''a stop made by closing the larynx''. Bell (1867, pp. 40, 60) defined a glottal stop as a glottal catch made with the glottis closed and a catch of the breath as in a cough, while specifying that the linguistic effect of a glottal stop is softer than in a cough. Sweet (1877, pp. 6-7) also called a glottal stop a glottal catch and defined it as a sudden opening or closing of the glottis. He also claimed that the most familiar example of a glottal catch is in an ordinary cough. [START_REF] Noël-Armfield | General phonetics, for missionaries and students of language[END_REF], p. 107), Heffner (1950, p. 125), and Jones (1956, p. 19) defined a glottal stop as a closure and opening of the glottis. Jones implied that the glottis must be tightly closed. P. Ladefoged (46 1975) andP. Ladefoged (1981, p. 50) states that a glottal stop is made by holding the vocal cords tightly together and also suggests that glottal stops occur in coughs. Laver (1994, pp. 187-188, 206) defines a glottal stop as a maintained complete glottal closure.

In most modern phonetic literature, therefore, a glottal stop is defined simply as a closed glottis or tightly closed glottis without any reference to the ventricular folds, arytenoid cartilages, or supraglottal cavity activities. (Esling, Fraser, and Jimmy G Harris, 2005, pp. 385-386) The two terms glottal stop and glottal constriction are considered to refer to two different phonetic phenomena by Sprigg (1966, p. 5), but according to Esling these belong to a continuum: "…glottal stops have been observed to occur on a continuum from a weakly constricted glottal stop to a strongly constricted glottal stop (…)" (Esling, Fraser, and Jimmy G Harris, 2005, p. 386).

A typical configuration observed in the production of a glottal stop "includes an adduction of the arytenoid cartilages, a complete adduction of the vocal folds, a partial adduction of the ventricular folds, and moderate narrowing of the laryngeal vestibule through its epilaryngeal sphincter mechanism (Esling, 1996, pp. 72-73, Esling, 1999, pp. 358-369;[START_REF] Harris | States of the glottis for voiceless plosives[END_REF]Jimmy G. Harris, 2001)" (Esling, Fraser, and Jimmy G Harris, 2005, p. 386).

The involvement of the ventricular folds is also noted in creaky voice by [START_REF] Esling | Voice quality: the laryngeal articulator model[END_REF].

Our research has confirmed that the ventricular folds can couple with the vocal folds during creaky phonation [START_REF] Moisik | Multimodal imaging of glottal stop and creaky voice: Evaluating the role of epilaryngeal constriction[END_REF]. This vocal-ventricular fold coupling has four effects: (1) it increases the overall effective vibrating mass, lowering frequency; (2) it adds damping, making vibration more likely to cease; (3) it adds increased degrees of freedom to the system, encouraging irregular vibration; and most importantly, (4) it perturbs the transmission of the mucosal wave by preventing its traversal across the surface of the vocal folds, causing the wave energy to be reflected back towards the midline earlier than that would occur for modal phonation [START_REF] Moisik | Modeling the biomechanical influence of epilaryngeal stricture on the vocal folds: A low-dimensional model of vocal-ventricular fold coupling[END_REF]. (Esling, Moisik, et al., 2019, p. 63) The above review highlights the very high level of complexity of the "valves of the throat", and thereby sheds light on why there is as yet no consensus on terminology. Similar gestures can have very different effects depending on their duration, their amplitude, and the overall configurations within which they take place. When examining electroglottographic signals, we should always remember that they constitute a projection onto a linear dimension of phenomena that are non-linear, and physiological interpretation needs to be put forward very carefully, as a matter of hypotheses, rather than reading gestures off the electroglottographic signal.

Glottalization as a component of lexical tone: an enduring challenge for phonology

The contribution that creaky voice makes to the tone system is apparent from the results set out in the previous chapter. Clearly, tone in Muong (as in Vietnamese) is to be understood in a broad sense that encompasses phonation-type characteristics associated to the phonologically distinctive suprasegmental units called tones. From the point of view of theoretical phonology, proposing models of phonation registers is no easy task.

…[P]honation register can usually be best viewed as a "package" comprising a variety of phonatory, pitch, and other properties, and it may sometimes be difficult to determine which of these, if any, is the most basic in a linguistic or perceptual sense. [START_REF] Clements | Do we need tone features?[END_REF].

Elaborating models for phonological units that are conventionally referred to as tones, but which incorporate phonation-type characteristics, such as Muong Tone 4, is part of the same challenge. There have been proposals to integrate phonation into a system of tone features, as a 'phonation register' feature. However, a review concludes that "arguments for tone features typically suffer from difficulties which make arguments for a register feature less than fully convincing" [START_REF] Clements | Do we need tone features?[END_REF].

In order to be in a better position to address this topic, which stands at the heart of the present research, it appears advisable to dwell further on the phonetics of the creaky tone in Muong, before proceeding to phonological generalizations. Accordingly, the following section ( §5.2) enters into some detail on creak and its subtypes, and the next ( §5.3) into the topic of detecting creak in recordings. The issue of glottalization in Kim Thuong Muong and its phonological modeling can then be returned to on a phonetically well-informed basis ( §5.4). All along, a tenet of the present analyses is that Tone 4 is best studied, not as a phenomenon of its own, but as a component of the tone system.

Electroglottography: principles and analysis methods

Since electroglottographic data play an important role in the present study, this exploratory technique warrants detailed presentation of its underlying principles and of the ways in which electroglottographic signals can be used in research.

Principles

The electroglottographic signal provides an estimate of variation in the contact area between the two vocal folds. Electroglottography (often abbreviated to EGG) was invented by Fabre in the mid-20th century. The initial report about the invention [START_REF] Fabre | Un procédé électrique percutané d'inscription de l'accolement glottique au cours de la phonation: glottographie de haute fréquence[END_REF] was followed by further studies by the same author over the following years (Fabre, 1958;Fabre, 1959;Fabre, 1961), initiating strands of research which continue to this day.

Electroglottography is a common, widespread technique that enables the investigation of vocal-fold contact area in phonation in an easy and noninvasive way. A high frequency modulated current (F = 1 MHz) is sent through the neck of the subject. Between the electrodes, electrical admittance varies with the vibratory movements of the vocal folds, increasing as the vocal folds increase in contact. [START_REF] Henrich | On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation[END_REF](Henrich et al., , p. 1321) ) The EGG signal is a continuous signal, like the audio. It can therefore be stored in the same format as the audio, and displayed with the same tools.

The following paragraphs address the topic of analysis of the EGG signal.

Methods to analyze the electroglottographic signal

The method chosen here for analysis of the electroglottographic signal uses its derivative signal (dEGG). Glottis-closure instants are approximated through detection of positive peaks in the first derivative of the signal, and glottis-opening instants through detection of negative peaks in-between the positive peaks. This method is set out in full by [START_REF] Henrich | On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation[END_REF]. Henrich's paper goes into technical detail concerning the four main phases of a glottal cycle: (i) closing phase, (ii) closed phase, (iii) opening phase, and (iv) open phase. Increase in vocal fold contact area is reflected by the closing phase (itself followed by the closed phase) in the electroglottographic signal, and the moment of fastest increase in vocal fold contact area corresponds to the glottis-closure instant. Decrease in vocal fold contact area begins during the closed phase, and continues into the opening phase; the moment of fastest decrease in vocal fold contact area is the glottis-opening instant.

But the correspondence between these four main phases, on the one hand, and detectable events on the electroglottographic signal, on the other hand, is not easy to establish. Instead, the electroglottographic signal corresponding to one glottal cycle can be divided into two portions only, as shown on Figure 2.14. These two portions are named closed phase and open phase of the vocal-fold vibratory cycle, and defined as follows: the closed phase extends from a glottis-closure instant to the next glottisopening instant; and the rest of the cycle is the open phase. (Greater detail is provided in [START_REF] Henrich | On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation[END_REF], pp. 1321-1322, as well as Childers and Krishnamurthy 1984[START_REF] Colton | Problems and pitfalls of electroglottography[END_REF][START_REF] Orlikoff | Scrambled EGG: the uses and abuses of electroglottography[END_REF] The derivative of the electroglottographic signal (dEGG) signal typically has a positive peak at glottis closure and a negative peak at glottis opening. Figure 2.14 illustrates visually a synchronization of EGG and dEGG signals. In the case of clear signals, one closing peak is clearly visible for each cycle, corresponding to the peak increase in vocal fold contact area and considered as the beginning of the glottal closed phase, and one (less salient) opening peak, corresponding to a peak in the decrease in vocal fold contact area and considered as the beginning of the glottal open phase. These peaks in the dEGG signal serve as the basis for estimating glottal parameters: mainly fundamental frequency and open quotient, the two parameters most used in the present study, and also the height of the closing peak (Derivative-Electroglottographic Closure Peak Amplitude), about which more below. Fundamental frequency (f 0 ) (unit: Hz) is the inverse of the glottal period (i.e. the inverse of glottal cycle duration). Specifically, f 0 dEGG is obtained by measuring the duration between two consecutive glottal closing instants, corresponding to a fundamental period. Its inverse gives the fundamental frequency of the voice (the formula is simple: F = 1 / T). The values of f 0 have pitch as their perceptual counterpart: low f 0 is heard as low pitch, and high f 0 as high pitch.

O q means glottal open quotient (unit: %). Measurement of O q dEGG requires measurement of the duration of the glottal cycle, plus detection of the glottal opening instant. This allows for computing the glottis-open interval; the open quotient is the ratio of the open-glottis interval to the entire cycle (the ratio between open time and fundamental period). This can be stated as the following equation: O q = (Open phase) / (Open phase+Closed phase). O q is a parameter that relates to phonation types: low O q demonstrates pressed phonation; medium O q reflects modal phonation; and high O q reflects flow phonation (whispery voice, shading into breathy voice). This relates to the following observation:

There might be a continuum of phonation types, defined in terms of the aperture between the arytenoid cartilages, ranging from voiceless (furthest apart), through breathy voiced, to regular, modal voicing, and then on through creaky voice to glottal closure (closest together). This continuum is depicted schematically in Figure 2.15. (Gordon and P. Ladefoged, 2001, p. 384) Figure 2.15: Continuum of phonation types (Reproduced from Gordon and P. Ladefoged, 2001, p. 384).

A strong motivation for adopting the dEGG method for estimating O q in the present study of linguistic tone is comparability across studies. This method is fairly widely used in phonetic studies of phonation types published since Nathalie Henrich's methodological article [START_REF] Michaud | Nasal release, nasal finals and tonal contrasts in Hanoi Vietnamese: an aerodynamic experiment[END_REF][START_REF] Mazaudon | Tonal contrasts and initial consonants: a case study of Tamang, a 'missing link' in tonogenesis[END_REF]Gao, 2016, e.g.), and also in various other phonetic studies (e.g. [START_REF] Recasens | Voicing assimilation in Catalan threeconsonant clusters[END_REF]. Use of similar algorithms facilitates comparison across studies, and hence across languages as well as across speakers and across datasets.

Moreover, the dEGG method is grounded in explicit assumptions that relate to physiological observations in a way which, although not simple and straightforward, is intuitively clear.

Criticism of estimation of the glottal open quotient by electroglottography

Estimation of the glottal open quotient by electroglottography has come under criticism, which it appears useful to review here. In a review article entitled "Electroglottgraphy -an update", Herbst (2020) recapitulates important caveats about the interpretation of the electroglottographic signal. Some of them are well-known: "Vocal fold vibration, a complex phenomenon taking place in three spatial dimensions, is mapped onto a single time-varying value" (Herbst, 2020, p. 4). It needs to be borne in mind that electroglottography provides a linear insight into phenomena that are not linear, and thus only offers glimpses into complex phenomena, which ideally need to be addressed through an array of exploratory techniques: a multisensor platform [START_REF] Vaissière | Multisensor platform for speech physiology research in a phonetics laboratory[END_REF]. But Herbst's criticism cuts deeper. He questions the assumption that underpins the method employed here: that peaks on the derivative of the electroglottographic signal provide reliable estimates of the timing of glottis-closure instants. Reviewing recent studies, he considers that they "strongly suggest that positive and negative dEGG peaks do not necessarily precisely coincide with GCI and GOI, a notion that was already put forward by Childers and Lee, who maintained that the EGG signal may not provide an exact indication for the instant of glottal closure" (Herbst, 2020, p. 7). As emphasized by [START_REF] Hampala | Relationship between the electroglottographic signal and vocal fold contact area[END_REF], "any quantitative and statistical data derived from EGG should be interpreted cautiously, allowing for potential deviations from true VFCA [Vocal Fold Contact Area]". But the criticism is then extended to the very notions of glottis-closure instant and glottis-opening instant: "vocal fold contacting and de-contacting (as measured by EGG) actually do not occur at infinitesimally small instants of time, but extend over a certain interval, particularly under the influence of anterior-posterior (…) and inferior-superior phase differences of vocal fold vibration" (Herbst 2020, p. 7;emphasis in original).

From a theoretical point of view, there may be a slight confusion here, as surely no one among users of the method of estimating f 0 and O q by means of peaks on the dEGG signal believes that glottal activity consists of instantaneous events of glottis closing and opening. The notions of glottis-closure instant and glottis-opening instant should, as a matter of course, be delivered complete with due precautions and careful hedging for their proper interpretation, but these precautions do not detract from the usefulness of these concepts. It should suffice to say once and for all that f 0 and O q as estimated through the dEGG method should not be confused with the physical parameter that they aim to capture. A good way to make this distinction consistently consists in embedding a reminder about the estimation method within the acronym used for the parameter. Therefore, the notations f 0 dEGG and O q dEGG are adopted throughout the present thesis to refer to the measured parameters, as distinct from f 0 and O q , the latter being understood either as abstract and ideal, or as generic label.

From a practical point of view, a key point here is what is meant by "precisely" when claiming that dEGG peaks do not coincide "precisely" with glottis-closure instants and glottis-opening instants. The weak claim that "perhaps the glottal area waveform, if available, would be a more suitable candidate" than the dEGG signal as a ground truth for glottal events is perfectly safe as a hypothesis, but hardly helpful for those to whom the glottal area waveform is simply not available. In practice, the difficulty of obtaining low-noise electroglottographic signals is a much more serious subject of concern to me than the fully accepted theoretical limitation whereby "the determination of contacting and de-contacting instants or events is an artificial concept" (Herbst, 2020, p. 10). The fact that glottis-opening instants as estimated from dEGG signals may be slightly earlier than those obtained by other methods does not detract from cross-token, cross-speaker and cross-language comparability, and common sense suggests that those are precious assets.

On topics of terminology, Herbst's proposals are not particularly straightforward to implement. He uses 'closed quotient' (C q ) rather than 'open quotient' (O q ), which is not a real difference at all: C q = 1 -O q He argues that 'closed quotient' should be replaced by 'contact quotient':

Given that the underlying EGG signal measures relative vocal fold contact area and not glottal closure, the terminology for that parameter should be limited to "contact quotient" instead of "closed quotient". Consequently, the term "open quotient" is also inappropriate, because EGG does not measure glottal opening. Instead, the term "quasi open quotient" (QOQ) might be used. (Herbst, 2020, p. 11) I leave it to more established researchers to decide whether to take the turn towards use of the term "quasi open quotient" (QOQ). Trying to weigh the advantages, I find them very slight, compared to O q dEGG . The suggestion to prefix "quasi" to the term "open quotient" strikes me as standing in contradiction to the statement (made by the author earlier on in the same paragraph) that this parameter "is not an ersatz closed quotient" (Herbst, 2020, p. 11). Among prefixes, "quasi" sounds like a reasonable equivalent for description as "ersatz": an inferior substitute or imitation, used to replace something that is unavailable and can only be approached, not equated.

Within studies related to electroglottography, "quasi" also brings to mind a proposal to build a "quasi-glottogram signal" from the electroglottographic signal [START_REF] Kochanski | A Quasi-glottogram signal for voicing and power estimation[END_REF]. While I can make no claim to understanding the maths sustaining the attempt to build a "quasi-glottogram signal", it is intuitively clear that the relationship between glottogram and electroglottogram in this proposal (published in the Journal of the Acoustical Society of America) was a much less straightforward one than that which links O q with O q dEGG . It does not seem completely fair or productive to dismiss O q dEGG along with all other estimations of the glottal open quotient through electroglottography.

These considerations close the section about electroglottography, and all that remains in the present Background chapter concerns the Muong language and the people who speak it.

2.5

The Muong people and the Muong language: a general view

The Muong as an officially recognized ethnic group

As a brief introduction to the target language and its speakers, this section recapitulates census information based on administrative categories, and historical and geographical information about the Muong (in Vietnamese: người Mường).

The Muong are currently the second largest of Vietnam's 53 officially recognized ethnic minority groups (after the Tày, speakers of a Tai-Kadai language), with an estimated population of roughly 1.4 million, based on the 2019 census. Their present area of settlement spreads out over an area west, southwest, and south of the Red River [START_REF] Lewis | Ethnologue: Languages of the world[END_REF]. They inhabit mountainous regions of northern Vietnam, with the greatest concentration in the provinces of Hoa Binh, Thanh Hoa (districts of Ngoc Lac, Thach Thanh, Cam Thuy, Ba Thuoc, Nhu Xuan, Lang Chanh), Phu Tho (districts of: Tan Son, where the fieldwork reported in this thesis was conducted; also: Thanh Sơn, Yen Lap, Ha Hoa), Son La (district of Phu Yen, Bac Yen, Moc Chau), and Nghe An. This distribution is reflected on the map of Vietic languages by Ferlus Ferlus (1998), reproduced here as Figure 2.16. In addition, Figure 2.17 by V.-T. [START_REF] Nguyen | The phonetics of the Mường language across its various dialects[END_REF] shows an overall picture of 91 Vietic dialects in northern Vietnam and neighboring areas, with special emphasis on Muong.

Muong communities are generally situated in low mountain valleys surrounded by peaks, i.e. in geographical zones contiguous with the Kinh (Vietnamese-speaking) majority, as opposed to the higher elevations typically inhabited by the Hmong or Dao. The Muong are subsistence farmers who cultivate rice (and more recently corn) as staples, alongside a number of cash crops including tea (in Phú Thọ), sugarcane (in Thanh Hóa, Phú Thọ, and Hòa Bình), and recently, acacia lumber (in Phú Thọ and Hòa Bình) [START_REF] Phan | Mường is not a subgroup: phonological evidence for a paraphyletic taxon in the Viet-Muong sub-family[END_REF].

The name Muong derives from a Tai word for 'principality', found in place names such as Muong Thanh, considered as the first center of Tai people when they settled in present-day Vietnam in the seventh century (in the area currently named Điện Biên Phủ). According to Trần Từ (i.e. Nguyễn Đức Từ Chi) [START_REF] Từ | Người Mường ở Hòa Bıǹh cũ[END_REF], Muong is a term used to describe an area of Muong residents that included many villages and that was ruled by an Assembly referred to in Vietnamese as "Nhà Lang" or "Thổ Lang". The original report is by Jeanne Cuisinier, in Les Muong: Géographie humaine et sociologie [START_REF] Wiley | Les Mu'ò'ng[END_REF]. 6 No details are provided about the historical time window when this system was in place; it may nonetheless be relevant to the linguistic history of the area that the administration tended to be entrusted by the imperial government to local rulers who apparently belonged to the local communities and can therefore be hypothesized to be speakers of the same language as the commoners.

The people officially classified as Muong call themselves /mol/, /mwăn/ in Hòa Bình, or /mon/, /mwal/in Thanh Hóa. In Phú Thọ, especially in the districts of Thanh Sơn and Tân Sơn, where the concentration of Muong people is greatest, and also in Yên Lập district and some communes of Thanh Thủy district, Muong people call themselves /mol/ or /mon/. These names are similar in terms of meaning: 'person'; this has been analyzed as having the etymology of 'burrower, digger', referring to the agricultural activity of horticulturists Ferlus, 1996, p. 8. They were borrowed into Vietnamese as "Mọi" or "Mọn", with a derogatory meaning carrying associations of backwardness. These labels have undergone a gradual demise since the introduction of "Muong" as an official name.

The Muong language in its Vietic context

Muong has unmistakable similarities with Vietnamese. This was pointed out by André-Georges Haudricourt in his article "The place of Vietnamese in Austroasiatic" (André-Georges Haudricourt, 1953). He discusses twelve words of basic vocabulary about names of body parts in Mon-Khmer languages, including: Vietnamese, Muong, Phong, Kuy, Mon, Bahnar, Mnong, and other languages. Among these, it can be seen from Table 2.1 that the correspondences between Vietnamese and Muong are really neat. Muong actually provided decisive evidence for the Austroasiatic affiliation of the Vietnamese language, which had heretofore variously been considered as belonging to Tai or Chinese. There is thus no need to labor the point that studies of the Muong language have some relevance to a better understanding of the history of the Viet-Muong group: Muong dialects can yield critical evidence for the historical study of Vietnamese.

Taking a closer look at the relationship between Muong and Vietnamese -a central issue in Muong studies -, various views have been expressed. Since the Vietnamese (Kinh) and the Muong are officially two distinct ethnic groups, each tends to be considered as having its own language, hence a perception that there exists one Muong language and one Vietnamese language, each with various dialects and sub-dialects. The linguist's perspective, on the other hand, consists in taking stock of the Viet-Muong language sub-group's internal diversity, and exploring the diachronic processes of evolution that shaped this diversity, without assuming a neat two-way divide.

Within the broader Vietic sub-group, Viet-Muong in the narrow sense, also known as Northern Vietic (including Vietnamese, Muong and Nguon) is characterized by irregular tonal reflexes in some words of basic vocabulary: the loss of proto-Austroasiatic initial voicing in Northern Vietic languages resulted in high-register reflexes, as against the expected low-register reflexes in Southern Vietic. This is interpreted by Ferlus (1999) as a substratum effect dating back to the time when proto-Vietic spread northwards onto an Austroasiatic substratum of languages that lacked voiced stops (a set of languages of which the Khmuic language Ksing Mul arguably constitutes a remnant). At that time, Vietnamese, Muong and Nguon dialects were not yet distinct. The historical scenario is that their common ancestor (proto-Northern Vietic) then spread over large areas of the plains of present-day Northern Vietnam. Overall, the varieties spoken in the area of present-day Hanoi underwent more rapid evolutions, due to a variety of factors that doubtlessly included contact between various dialects and languages. Among these, one variety became dominant, and gained the status of a regional, then a national standard: the Vietnamese language. By contrast with speakers of Northern Vietic in peripheral areas, those in the area of Thăng Long (present-day Hanoi) tended to be identified by their status as townspeople, hence the name Kinh (the Sino-Vietnamese word for 'capital city', 京: the same that constitutes the second syllable in 'Beijing' 北京; this is also the second character found in Tokyo, whose name in Chinese characters is identical to one of Hanoi's former names: Đông Kinh 東京). This process is still active today: Frédéric Pain (p.c. 2014) observed that some proud city dwellers prefer to be identified as 'Hanoians' (người Hà Nội) in preference to the label 'Kinh', which is now used over the entire country as the label for the 'majority' ethnic group, and is hence less prestigious, having lost its specific association to citizenship of the capital.

Detailed ethnolinguistic study of the sense of ethnic belonging of the various communities of speakers of Northern Vietic falls outside the scope of the present study; the above remarks simply aimed to convey a feel for the gradual individuation of the Vietnamese language within Viet-Muong, a process which sheds light on the special synchronic closeness between Muong and Vietnamese.

The phonological evolution of the peripheral dialects now identified as "Muong" was less dramatic than that of Vietnamese, resulting in a more conservative phonological system, closer in some respects to proto-Northern Vietic. One of the telltale evolutions that single out Vietnamese within the Vietic sub-group is the spirantization of medial obstruents, which results in phonological correspondences such as Muong /ka/ :: Viet /ɣa/ 'chicken'. In Muong, the proto-Vietic presyllable was lost without compensation; in Vietnamese, it caused the spirantization of /*ɣ/ (Ferlus, 1982).

Literature review of Muong studies

A full review of linguistic studies of Muong will not be attempted here. Let us simply mention that Milton and Muriel Barker collected abundant lexical data, made available as a Muong-Vietnamese-English Dictionary: an extensive wordlist with Vietnamese and English glosses (M. E. [START_REF] Barker | Mường-Vietnamese-English dictionary[END_REF]. In addition, Miriam Barker published a bibliography of Muong and other Vietic languages in 1993, with over 40 pages of references not only in the field of linguistic studies, but also in fields such as literature, geography and history (Miriam A. [START_REF] Barker | Bibliography of Mường and other Vietic language groups, with notes[END_REF]. This was a key reference in gathering documentation for the present work.

Later, V.-T. [START_REF] Nguyen | The phonetics of the Mường language across its various dialects[END_REF] collected data from an impressive range of 30 dialects. This is a remarkable resource to get a feel for the diversity of dialects; on the other hand, the book suffers from fairly unreliable tonal transcriptions (Ferlus p.c. 2015, confirmed by my own observations). It is a general observation that native speakers of Vietnamese can find it difficult to cast off the perceptual filter of their mother tongue and attune their ear to different tone systems.

Within the limited scope of the present study, other references about the Muong language have not yet been taken into account.

The dialect under study: Kim Thuong Muong

The variety of Muong under study here is one of the many Muong dialects found in Phú Thọ province. The exact location of fieldwork is Kim Thuong commune, Tan Son district,7 hence the label used here for this dialect: Kim Thuong Muong. Over 85% of the population in this district belongs to ethnic minorities. Among them, Muong make up more than 75%, and Dao account for about 6,4%, the remaining belongs to Hmông and Tày. Locally, the nation's "majority" ethnic group, the Kinh, are thus among the smallest minorities in terms of population. The Dao and Muong each form a community with festivals and habits of its own; members of other groups, such as Kinh, Tày and Hmông people, are new settlers or married into one of the two local communities. This is a mountainous region that is difficult to access: a relatively locked area surrounded by mountains and rivers. This can be predicted to be conducive to the preservation of linguistic diversity. To the northwest is Xuân Sơn National Park; to the southwest is Đà River, which separates this area from Hoà Bình province, which contains areas of denser Muong population (see map: Figure 2.18). The East and the South border on other Muong dialects of Tan Son district. This configuration goes a long way towards explaining why Kim Thuong Muong is still spoken today, and has not yet been entirely replaced by Vietnamese. All the local people I encountered proudly referred to themselves as /mɯəŋ² tăn²/ (in Vietnamese orthography, this can be rendered as Mường Tằn), meaning 'the original Muong' (from my field notes, it would seem that /tăn²/ means 'original, pristine').

To this day, Muong is essentially an unwritten language. Some romanized writing systems were devised, and used in sizeable publications of collections of oral literature (e.g. Bùi 2010) but have not been widely adopted by the general public. Schooling is exclusively in Vietnamese, and is compulsory from age 6 to age 17.

While the target dialect of the present study (Kim Thuong Muong) has never studied before in its own right, it is geographically close to areas whose dialects have been studied, such as Kha Cuu Muong studied by [START_REF] Phan | Mường is not a subgroup: phonological evidence for a paraphyletic taxon in the Viet-Muong sub-family[END_REF], and Giap Lai Muong, one of the 30 dialects studied in Van-Tai Nguyen's book (V.-T. [START_REF] Nguyen | The phonetics of the Mường language across its various dialects[END_REF]. In regard to the current sociolinguistic situation, the Muong language in general and Kim Thuong Muong in particular are still vital and in everyday use. The risk of weakening and loss is not really obvious. However, it does not mean that the study of Muong is not urgent. From my point of view, research on Muong Kim Thuong at this time is reasonable because we can avail ourselves of the many advantages of studying a language that is still widely used: (i) ease for gathering information and data for study since Muong is still a living language; (ii) ease for verification Muong language's characteristics since the contact between it and other languages, especially Vietnamese, is not too complicated. Moreover, facing the powerful influence of Vietnamese, Muong language is clearly in danger of being weakened, and disappearing in the mid run.

Because of its relationship to Vietnamese and to the other languages of the Vietic group (such as: Chứt, Cuối, and Thà Vựng), the growth of Muong studies since the early twentieth century not only helps us to have a better understanding of this individual language, but also is useful for comparative study and diachronic study.

Clearly, the amount of research on Muong is much more limited than on Vietnamese, in terms of both quantity and quality. Given the overall context of Muong studies, my dissertation was done with the desire to make a contribution (however small) towards a better understanding of this language, starting with a fully worked out phonemic inventory.

Some notes about the social dynamics of Kim Thuong Muong. Kim Thuong Muong is a non-written language variety inside a dialect continuum characterized by indepth influence from the national standard -Hanoi Vietnamese. The Muong language remains locally vigorous; at the same time, Hanoi Vietnamese is clearly a prestige language, whose acquisition is key to success in school -opening prospects for a brighter future and better work opportunities outside Kim Thuong.

Kim Thuong Muong is defined as the dialect of the (few) villages of Kim Thuong commune. In terms of social status, this is the strongest group in this area with a population that makes up more than 75% of the total. The rest is divided among four groups: Dao, H'mông, Tày, Kinh, which differ sharply from one another. Locally, the nation's "majority" ethnic group, the Kinh, are thus among the smallest minorities in terms of population. The Dao and Muong each form a community with festivals and habits of its own; members of other groups, such as Kinh, Tày and Hmông people, are new settlers or married into one of the two local communities. Its peripheral location in geographic terms would seem to make Kim Thuong Muong more likely to endure than other varieties of Muong. Contact between the Muong and Dao is not strong: Dao group lives separately in areas that have more difficult terrain. Local people refer to the respective habitats of the Dao and Muong as "khu trên" and "khu dưới" (meaning upper and lower zone, respectively). This can be seen as the acknowledgment of a difference between the two groups' current settlement: the lowlands to the Muong, the highlands to the Dao. It could be that this description also reflects that the two should remain distinct: affirming their distinctness. Due to their current living habits and standards, the Dao people are not engaged in particularly active trade exchanges, nor are they greatly integrated to the network of health and education services. Therefore, despite geographic proximity, contact between the Dao and Muong in Kim Thuong is relatively loose. As to ethnic H'mông and Tày, they live interspersed within the Muong community but their number is very small and studying their interaction with their surroundings, and their potential influence on Kim Thuong Muong, would require specific case studies (a monograph about a household, for instance) which I can hardly hope to conduct, for want of having any knowledge of their mother language.

As for 'Kinh' newcomers to the area, their influence is linked to their status as representatives of the ethnic majority of Vietnam. From my field observation, local people in Kim Thuong have a positive attitude to their mother language. All the local people that I have met use their mother language for day-to-day communication. Individuals who belong to a different ethnic group but have married into the Kim Thuong Muong community also tend to fall in line with local people by learning and using this language, yielding to a demand that seems overwhelming. Therefore, the Kim Thuong Muong dialect keeps the role of the strongest language in this community to this day. On the other hand, it seems clear that Kim Thuong Muong is influenced by the "Kinh" language (Hanoi Vietnamese) much more than by any other. There is strong contact in many aspects. Firstly, the development of commercial relations created an opportunity for Muong people in Kim Thuong to use Vietnamese to communicate and trade. Vietnamese now becomes the main language in the market, standardly used between people unacquainted with each other. Secondly, the role of Vietnamese is becoming increasingly important in the Kim Thuong Muong community, as the language of education, health services, and administrative affairs. Nowadays, children are educated in Vietnamese from the beginning of their schooling. Vietnamese is also the language used for television, radio, and other media mass. Because Kim Thuong Muong in particular and Muong language in general have no writing, they have to use Vietnamese for administrative documents to address the affairs of their community. Last but not least, local people recently tend to go out of their area, mainly going into "Kinh" communities, to seek employment when farm work ends. Those reasons explain why almost 100% Muong people in Kim Thuong are able to use Vietnamese (to different extents). The stage is thus set for strong contact between Kim Thuong Muong dialect and Vietnamese, leading to language variation and change in Kim Thuong Muong.

The predicament encountered when running an experiment using nonsense words (as part of my Master's study: M.-C. Nguyên 2016) is a case in point: the consultants tend to identify Muong tones with their phonetically closest equivalent in Standard Vietnamese, resulting in confusion of Tone 1 and Tone 2. The consultants' great difficulties when required to steer clear of Standard Vietnamese tones and focus solely on the pronunciation of their mother tongue shows that they have much greater metalinguistic awareness about their second language than about their mother tongue. For them, metalinguistic notions of 'tone' are so strongly linked to Vietnamese (the language which they learned to analyze into phonemes in the process of learning Vietnamese writing) that special training is required for them to develop an awareness of their mother tongue's categories. This could seem paradoxical, but is probably widespread in communities whose mother tongue is an unwritten language in a context of unequal bilingualism.

Although sociolinguistics and language contact were not intended as the main topic of the present research, it is clear that these are simply unavoidable. Any study of Kim Thuong Muong in particular and Vietic languages in general needs to include special precautions and verifications concerning possible interferences from Vietnamese. Since there is no way to deny or avoid this complexity, the way forward seems to be to embrace the complexity and give it a central place in the research. As a speaker of Vietnamese, and a 'Kinh' newcomer to the community (no matter how much effort is spent making my presence inconspicuous and unobtrusive), I am fortunate to be a witness to cases of code-switching, blending and other phenomena, which I intend to document through field notes, with the possible mid-and long-term prospect of a sociolinguistic survey using the methods gradually developed in sociolinguistics from [START_REF] Weinreich | On the description of phonic interference[END_REF], [START_REF] Weinreich | Empirical foundations for a theory of language change[END_REF][START_REF] Weinreich | Empirical foundations for a theory of language change[END_REF]Weinreich (2011) to [START_REF] Labov | Principles of linguistic change. Internal factors[END_REF], Labov (2001), andLabov (2010).

Phonemic inventory of Kim Thuong Muong

The present section was written in the spirit of "Illustrations of the IPA": phoneme inventories accompanied by some observations about the phonological system.

In order to explore and propose a phonemic inventory of a language/dialect, a prerequisite is that the researcher knows the International Phonetic Alphabet (IPA) 8 . In order to phonemicize the data, one needs to conduct a distributional analysis along the basic principles of phonemic theory (Chao, 1934;[START_REF] Pike | Phonemics: a technique for reducing languages to writing[END_REF][START_REF] Martinet | La Description phonologique avec application au parler franco-provençal d'Hauteville (Savoie)[END_REF].

The inventories below are synthesized by vocabularies collected from Michel Ferlus' word list, an expanded version of the EFEO-CNRS-SOAS word list for linguistic fieldwork in Southeast Asia, available online : https://hal.archives-ouvertes.fr/ halshs-01068533/

Concerning the practical methodology in the field, the ideal way to collect the vocabularies is to have an assistant with you during the recording session who can read the words so that the speaker can pronounce the corresponding words in his/her language. At the same time, the researcher can transcribe them directly to a computer using the word list. Of course, this is only convenient in case there is an IPA keyboard available on your computer9 . Otherwise, we can also print out the word list and transcribe them manually and later type them into the Excel file. This admittedly takes twice as long, but in my experience it allows for better contact with the consultants, focusing on a meaningful exchange. Data inputting can cause an interruption of sorts within the recording session: using a computer almost amounts to having a silent 'third party' present, out of touch with the consultant (unlike a research assistant: a human 'third party').

Kim Thuong Muong is the first language that I really described in the field. Beginners' work tends to be slow: Michel Ferlus (personal communication 2015) reports that the first language for which he carried out the phonemic analysis task, namely Khmu, took him a full six month to work out. He reflected that a couple of decades later, rich with experience from working on dozens of languages, he could have done it in the space of three weeks. But as far as vowels and consonants are concerned, I did not have much difficulty in accessing the dialect being studied. For one thing, Muong is not a difficult language in terms of its sound system (as noted by Michel Ferlus: again, this is a personal communication from 2015). Moreover, my mother tongue is Vietnamese, which is the language most closely related to Muong. Knowledge of the IPA and training in transcribing the Vietnamese in IPA (Kirby, 2011) are basic requirements in undergraduate linguistics courses, along with knowledge of the historical phonology of the Viet-Muong (Vietic) branch of Austroasiatic languages. In addition, there is a broad array of references about various other dialects of Muong, as well as on other languages of the Vietic group. Special mention needs to be made of the work of V.-T. [START_REF] Nguyen | The phonetics of the Mường language across its various dialects[END_REF] on the phonetics of no less than thirty Muong dialects, and of the successive publications by Michel Ferlus on several dialects of Vietic languages such as Lang Lo Tho (Ferlus, 2001), Arem (Ferlus, 2013), and heterodox dialects of Vietnamese such as Cao Lao Ha (Ferlus, 1995) and Phong Nha (a study in which I was fortunate to participate: (Michaud, Ferlus, and M.-C. Nguyên, 2015)). Familiarity with these sources makes it possible to anticipate a set of expected phonemes, as well as phonotactic rules (concerning expected combinations of phonemes). Thus, I was able to notice in Kim Thuong Muong the contrastive palatal finals /c/, /ɲ/ because I was aware that these sounds, even though they do not exist anymore in Vietnamese as separate phonemes, used to be present at earlier stages of Vietic and are preserved in several varieties of Muong.

Thus, the phonemic system was collected, synthesized and systematized as follows.

Consonants

Initial consonants

An inventory of initial consonants is shown in Table 2.2. Among the phonemes in Table 2.2, /w/ is as a newcomer to the system, appearing on loanwords from Vietnamese, which have initial /v/ in Vietnamese.

Tones

For the study of tones, prior knowledge of closely related languages may paradoxically bring disadvantages. Speakers of Vietnamese as a first language realize, to their dismay and sometimes to their utter distress, that re-training their ear to a new tonal language, as is necessary in fieldwork [START_REF] Rice | On beginning the study of the tone system of a Dene (Athabaskan) language: Looking back[END_REF], is especially difficult when one has Vietnamese tones in one's mind since infancy. A piece of anecdotal evidence on this topic is [START_REF] Adams | Phonemic transcription of low-resource tonal languages[END_REF] immediately asked whether the software could identify tones for them, solving what they felt to be an impossible task for their ear. Whether the language under study is from the Austroasiatic family (to which Vietnamese belongs) or to Tai-Kadai, Hmong-Mien or Sino-Tibetan, making out the tone system is perceived as excruciatingly difficult and uncertain by scholars with Vietnamese as their mother tongue (Alexis Michaud, personal communication 2018). To what extent this impression matches real performance remains to be investigated. It could be the case that adjusting one's ear to a new tone system is a challenge for anyone, and that some people (for reasons not directly related to the languages they speak) are less attracted to this challenge than others. There nonetheless seem to be some converging indications to the effect that speakers of a phonetically complex tone system such as Vietnamese experience special difficulty in casting aside the phonological filter of their native language and adopting that of another tonal language.

Be the statistic as it may, I for one can certainly report experiencing this difficulty. When I discovered the Kim Thuong Muong tone system, carry-over of tone identification patterns from Vietnamese was a major hurdle, and the tendency to fall back on Vietnamese categories caused me to make some worrying mistakes in perceiving and classifying Muong tones. I found myself constantly trying to figure out which tone in Kim Thuong Muong was similar to which tone in Vietnamese. As a consequence, I initially missed the (contrastive) distinction between the falling tone (Tone 2) and the low level tone (Tone 1). I perceived both as the same tone: a tone characterized by a falling modulation. I failed to notice the differences because I based myself on a comparison with the Vietnamese A2 tone (called thanh huyền in Vietnamese orthography). Therefore, back in 2015 I initially came up with an analysis of the tonal system of Kim Thuong Muong with only 4 tones on smooth syllables. This mistake was detected only when my attention was brought to the minimal pair /ka1/ "chicken" and /ka2/ "big". It took me quite a while to progress from initial recognition of this distinction (thanks to the patient help of language consultants) to consistent and confident use.

If anything could make me believe in hard-wired linguistic competence, then that is Vietnamese tones, which I still feel 'hard-wired' to perceive, as opposed to the painstaking adoption of the tonological filter of Kim Thuong Muong. It felt like a process of unlearning one's prior tone system to learn the new one -even though that is not literally the case, since I have not un-learned Vietnamese tones. Maybe the challenge can be compared to that of speakers of Dutch learning German and vice versa: there is special difficulty in keeping separate two linguistic systems that have so many points of similarity, tantalizing close to identity. Studies of language acquisition may shed light on my feeling that the Vietnamese tone system plants deep roots in native speakers.

This learning experience sheds light on possible processes of language change in cases of language replacement: it could well be the case that a group of Vietnamese learners who switched to Kim Thuong Muong (for reasons which in the present sociolinguistic scene would be truly implausible) would end up speaking a four-tone language, collapsing the falling tone (Tone 2) and the low level tone (Tone 1) together.

Diachronic background

Tonogenesis in Vietnamese is among the success stories of 20th-century historical linguistics, and specifically, of Panchronic Phonology: an approach to diachronic phonology that searches for regularities independent of a specific language group and a specific point in time, i.e. true laws of sound change. The seminal findings of André-Georges Haudricourt (1954a) and André-Georges Haudricourt (1954b) are now part of the common background knowledge of specialists of Asian languages (for a summary, see e.g. Michaud 2012). A study of the historical development of tone in all the Vietic languages for which documentation was available at the time (1998) is proposed by Ferlus (1998). This constitutes fundamental background for the present study: the system for etymological notation of tones used here (from A1 to C2 for smooth syllables, those without final stops, and D1 and D2 for stopped syllables -also called checked syllables -, those with final stops) is taken up from the usual conventions set out in these diachronic studies, to which the reader is referred for further details.

The tone categories

The nature of tone itself raises issues in choosing notations for some tones of Southeast Asian languages. It seems that the tones are defined through the set of contrasts into which they enter with one another, rather than by a neat phonological property (such as the H, M and L tones of the Naxi language, for instance: Michaud, Vaissière, and M.-C. Nguyên 2015). Transcribing this type of tone in phonetic notation remains an unsolved issue. The 1949 edition of the Principles of the International Phonetic Association mentioned the case of Vietnamese (referred to as 'Annamese'): " ˘and ˅ (preceding the syllable) have been suggested for the two rising tones of Annamese, ˘implying the use of breathy voice and ˅ for creaky voice" (p. 18). The intended tones are presumably B1 and C2. To my knowledge, these symbols (the macron [ ˘] and the down arrowhead [ ˅ ]) have not been taken up in later studies. An issue is that use of the macron [ ˘] for one of the tones threatens to conflict with its use to indicate vowel shortness: in Vietnamese orthographic representation, ă is a short vowel, contrasting with a. As orthographic representation happens to coincide with IPA transcription for these two vowels, using the macron [ ˘] to indicate tone would contradict a well-established convention.

One possibility is to assign numbers to tones, without committing oneself to an analysis. This is the choice made for Mandarin Chinese, whose four tones are referred to as 'first tone', 'second tone', 'third tone' and 'fourth tone' in the linguistic literaturea practice that speaks volumes about linguists' puzzle: the use of numbers amounts to giving up the analysis, and recognizing that there is no easy way to pinpoint the exact nature of each of the tones. Use of numbers for tones is also widespread in the field of Thai (Siamese) studies: numbering the tones of Standard Thai from one to five allows for a straightforward identification of the synchronic categories. Interestingly, the earlier categorization of Thai tones, dating back to a time when there were only three contrastive tones, was also by means of numbers: Mai Ek เสี ยงเอก means 'tone one' and Mai Tho เสี ยงโท means 'tone two'. These contrasted with a third category, left unmarked: เสี ยงสามั ญ. This system is adopted here: classical distributional analysis conducted during fieldwork brought out five distinctive tones for smooth syllables and two tones for stopped syllables, and these tones are numbered from 1 to 7 in Table 2.6.

Another possibility is to adopt Chao Yuen-ren's system of five levels [START_REF] Chao | A system of tone letters[END_REF], to propose a stylized representation of the perceived pitch along a scale from 1 (lowest) to 5 (highest). A mid-rising tone may thus be represented as 24, 25, 34, 35, or 45. Parameters guiding the choice of one level along the five-point scale include phonetic precision and phonemic economy, which may occasionally be at odds with each other. In particular, it is recommended to use no more numbers than is phonemically necessary, i.e. use the numbers sparingly: for instance, if only three levels are necessary for the target language, these should be transcribed as 1, 3 and 5, and use of 2 and 4 would be avoided. It is for each researcher to strike a balance between economy and precision. A limitation of this system is that it does not transcribe phonation types. In Hanoi Vietnamese, laryngealization plays an important role for two of the tones, namely B2 and C2; moreover, phonation-type characteristics may be found on other tones, to a greater or lesser extent (see Brunelle 2009b). Keeping this limitation in mind, Chao's system is nonetheless useful, and is a de facto standard in the description of tone in East Asian languages; for these two reasons, stylizations of the tones of Kim Thuong Muong using Chao's system are provided in Table 2.6.

The description of Vietnamese tones by Kirby (2011) served as a reference in the present description. Of course the tone system of Kim Thuong Muong is treated here as a system in its own right, not as a variant of the tone system of Vietnamese; on the other hand, Vietnamese offered a convenient point of comparison. For instance, the adoption of the label 33 in J. Kirby's description of Hanoi Vietnamese tone A1 (ngang) led me to adopt this label for Tone 1 of Kim Thuong Muong, which is somewhat similar though a bit lower than the Vietnamese tone A1.

Etymological tone categories in Kim Thuong Muong

The tonogenesis of the Viet-Muong group, as in most East Asian languages, is the result of two distinct phenomena (André-Georges Haudricourt, 1954b;Ferlus, 1998):

• (i) a two-way splitting composed by the confusion of the two kinds of initial consonants: voiceless (made up the series of high register) and voice (made up the series of low register); • (ii) a three way splitting caused by the loss of two kinds of final consonants: on the one hand the glottal the glottal stop /-ˀ/ or glottal constriction /-ʔ/, on the other hand the final spirant /-h/, which made up tonal categories B and C respectively. Basically, this process brought out a tonal frame for languages of Viet-Muong group with 6-tones (in smooth syllables). The basic tonal system and the diversity of realizations in the dialects Muong are the same as in Vietnamese. There are a few dialects of Muong that have 6 tones like northern Vietnamese, such as Muong Dam in Hoa Binh which reported by Ferlus (1998). Most other dialects have 5 tones with B2 -C2 confusion (V.-T. [START_REF] Nguyen | The phonetics of the Mường language across its various dialects[END_REF]. Figure 2.19 shows the tone box of Kim Thuong Muong. It indicates a merger of etymological categories A2 and C2. This is not an unprecedented phenomenon. In fact we already have encountered similar cases in a Nguon dialect in Quang Binh, which is supposedly Muong language in central Vietnam (Ferlus, 1998). Table 2.7 provides some examples of this confusion.

Going back to the topic of the glottalized tone, Tone 4 of Kim Thuong Muong derived from an ancient final glottal constriction /-ʔ/, i.e., B position according to tone box's label. We can find numerous correspondences between this tone of Muong and two Vietnamese tones which belong to the same category: tone 'sắc' B1 in most cases and tone 'nặng' B2 in a few cases. Refer to the discussion of André-Georges Haudricourt (1961) Glottalization in category B also found in other Muong dialects according to Ferlus' report (Ferlus, 1998, p. 8), such as Muong Dam (Hoa Binh) -tone [21'], Muong Tan Phong (Son La) -Tone [312'], and Nguon (Boc Tho) -Tone [313'] and [54']. He use an apostrophe to mark the existence of glottalization. It seems that this prevalence of glottalization, especially of creaky voice in Muong dialects was a factor that led [START_REF] Diffloth | Proto-Austroasiatic creaky voice[END_REF] to the reconstruction of a phonation type contrast between creaky voice and clear voice in Proto-Autroasiatic. Indeed, his proposal was based mainly on evidence from Katuic, Pearic and Vietic languages. However, this hypothesis was later re-examined and denied by Ferlus (2004).

Chapter 3 Method

Openness and clarity on topics of method are especially crucial to research which aims at the highest standards of Open Science. Hence, much detail will be provided in this chapter on how the present study was conducted. I will elaborate on each of the successive steps I have taken: selecting speech materials, designing the speech production experiment, and analyzing and vizualizing the data.

In addition to the above topics, which are routinely covered in the Method section of phonetic studies, the present chapter will place emphasis on two aspects that have often received somewhat less attention in phonetic/phonological studies. One is the process of preparing data sets for archiving and online distribution, with a view to data reusability in future, and to hand-in-hand cumulative progress in documentation and research. Another aspect concerns the sociolinguistic context to the study: it appears relevant to start out the present chapter by explaining some of the specificities of fieldwork experiments to an audience of phoneticians/phonologists, without assuming any experience of immersion fieldwork on the part of readers.

To facilitate the reading of this chapter, all details related but not directly focused on the methodology of this thesis will be organized in the appendix with a mention in the main text.

Speech materials

The use of minimal sets is ideal for the study of tones, as it offers a way to compare tokens while keeping intrinsic properties of segmental phonemes constant: such as intrinsic pitch and co-articulatory influences from surrounding consonants [START_REF] Hombert | Consonant types, vowel quality and tone[END_REF][START_REF] Whalen | The universality of intrinsic F0 of vowels[END_REF]. Keeping in mind that "[s]tudies of non-citation forms of tones in different prosodic positions help elucidate listener behavior in tonal identification",1 some narratives were also elicited.

The target words of the experiment belong to 12 minimal sets that contrast for tone in smooth syllables (i.e., open syllables or syllables ending with a nasal coda) and 3 minimal pairs that contrast for tone in checked syllables (i.e., syllables ending with a stop coda).

These minimal sets and pairs were an extension of the list available with only 2 minimal sets in 2016. The method was based on 2961 vocabularies from the EFEO-CNRS-SOAS word list. The details of strategies for searching minimal sets and pairs for the study of the tone system will be mentioned in the appendix A. This appendix is intended to clarify the entire procedure of this study and hopefully it will be a useful documentation and suggestion for people who want to start studying the tone system in particular and phoneme inventories in general, in undocumented and unwritten languages.

List of the (near-) minimal sets

Tables 3.1 and 3.2 provide full detail about the minimal sets and pairs. The tables include:

• First column: The numbering of minimal sets (from 1 to 12) and minimal pairs (from 1 to 3). • Second column: The numbering of target syllables, labeled as "UID" (for "Unique

Identifier") because this number constitutes the unique identifier of target syllables. This number is used in the annotation of audio files, and in data processing down the line. • Third column: The target syllables. These constitute the actual speech material of the recording session. In other words, the speakers were asked to pronounce these monosyllabic morphemes (roots). • Fourth column: The full form of the target words from which monosyllables were extracted, in cases where the usual form of the word at issue is disyllabic. This point will be elaborated on below. • Fifth-sixth-seventh columns: The translations in English, French and Vietnamese, respectively. Initially, I was able to put together a total of 13 minimal sets and 6 minimal pairs from my vocabulary lists. However, one set and three pairs were removed from the list when it turned out, in the course of recordings, that they were not exactly minimal contrasts: there were mistakes in my initial transcriptions of the rhymes of some of the words. It needs to be kept in mind that there is as yet no dictionary or reference grammar of Kim Thuong Muong, and the analyses still constitute work in progress, even for some aspects of the language's phonological system. The lines in gray text at bottom of tables reflect the 'bootstrapping' nature of the work: they contain the spurious set and pairs, which were included in the recording sessions from several speakers (before the issue was noticed). Even though these tokens were not processed at the stages of data annotation and parameter extraction, they are present in the recordings. The files are archived as is for the sake of preserving the integrity of the original recordings; for the sake of consistency between the primary data and the analyses based on it, it seemed advisable to include the stray syllables in Tables 3.1 and3.2. Overall, true-and-tested minimal sets are not easy to come by. Near-minimal sets, on the other hand, are easier to find.

Pairs that show segments in nearly identical environments, such as azure/assure or author/either, are called near-minimal pairs. They help to establish contrasts where no minimal pairs can be found. [START_REF] Dobrovolsky | Phonology: the function and patterning of sounds[END_REF].

As only eight proper minimal sets (distinguished only by tone) were found, four near-minimal sets were added. The syllables in the latter sets differ not only by tone but also by initial consonant.

Even though the constraint on segmental identity was relaxed in order to obtain these additional sets, it was not lifted altogether: the alternative consonants are immediately adjacent to the target phonemes in the International Phonetic Alphabet chart. In other words, they have the same manner of articulation as well as a nearby point of articulation (i.e. a strong similarity in terms of place of articulation). 2 Use of near-minimal pairs is widespread in phonetic studies to circumvent the commonly encountered difficulty of finding minimally contrasting environments for phonemes (see e.g. [START_REF] Barlow | Minimal pair approaches to phonological remediation[END_REF][START_REF] Boer | First formant difference for /i/ and /u/: A cross-linguistic study and an explanation[END_REF][START_REF] Garellek | Perception of glottalization and phrase-final creak[END_REF]. Table 3.1: Speech materials: eight minimal sets and four near-minimal sets that contrast for five tones in smooth syllables. The sets in Table 3.1 and the pairs in Table 3.2 are not ordered by a principled criterion such as the order of the alphabet: they are simply listed in the order in which I put them together. The first two sets were ready to use from my previous study (M.-C. Nguyên, 2016, p. 20), and the rest were added since then based on the progress of the vocabulary collection task (which constitutes one of the language documentation "background tasks" to the present study). The strategy for finding the (near-) minimal sets is elaborated on in Appendix A.

N. UID

Target syllable

Complete word

English

The eight bona fide minimal sets are placed before the four near-minimal sets. The three minimal pairs are listed separately, in another table, to reflect the fact that from a structural perspective stop-final syllables belong to another tonal sub-system than the others (the smooth syllables).

The fact that Unique Identifiers (UIDs) were assigned early on (for the sake of data annotation) led me to retain the same ordering of sets later on, even though it is not grounded in phonological principles. A paramount concern is to ensure consistency between the corpus description and the actual data files. Updating a system of numeral unique identifiers is an error-prone process, so I chose to avoid changing the labeling of items, and thus I kept the original order. I wish to apologize to readers who have difficulties finding their way through these lists.

Another thing to note here is that the order of the tones in the minimal sets was also not placed in ascending or descending order according to tone label numbers but in the order: Tone 5 -Tone 3 -Tone 2 -Tone 1 -Tone 4. This is not a random order, we arrange them with the aim of maximizing the distinction between the tones. The labeling of tones in numbers is completely arbitrary, unrelated to any phonetic or phonological characteristic. During designing the experiment of minimal sets, we reorder them according to their relative descent in pitch level in order to optimize the tonal space. This follows the common tendency of f 0 declination in paragraph prosody, which is similar to sentence but in the next level. The work of Vaissière and Michaud (2006, p. 5) affirms this tendency that:

The paragraph is the largest unit. The highest f 0 value in each sentence tends to decline from the first to the last sentence in a paragraph, in French and in other languages [START_REF] Lehiste | The phonetic structure of paragraphs[END_REF]. The end of the paragraph typically ends on an extra-low f 0 (often leading to a change in voice quality) and intensity.

Figure 3.1, reproduced from [START_REF] Vaissière | Prosodic constituents in French: a datadriven approach[END_REF], shows an attempt to model this phenomenon.

Therefore, in the series, the first tone is Tone 5, the highest tone, and the last tone is the lowest tone, that is Tone 4. Tone 1 was easily placed in the penultimate position, before Tone 4, since it is consistently in the low-mid range, just above the creaky tone. The remaining two tones are an ascending tone (Tone 3) and a descending tone (Tone 2). Although normally the rise in Tone 3 is not as prominent as the fall in Tone 2, I placed Tone 2 after Tone 3 on purpose. Tone 2 is thereby placed just before Tone 1, highlighting the contrast between these two tones which I sometimes Figure 3.1: General outline of the f 0 curve of an affirmative statement [START_REF] Vaissière | Language-independent prosodic features[END_REF].

Reproduced from [START_REF] Vaissière | Prosodic constituents in French: a datadriven approach[END_REF], with permission.

struggle to distinguish aurally from each other. By placing them close together, the speaker will be led to pronounce them with maximum distinction. That will help me to perceive the difference better, and thus to monitor recording sessions better, making sure that there is no confusion between the two tones during the experiment.

Some limitations of the materials

Although efforts were made to improve over shortcomings noted in a previous study -reported in my 2016 M.A. thesis: M.-C. Nguyên 2016, pp. 20-21-, the materials here still suffer from certain limitations. Some of these limitations may well be unavoidable, as they relate to important dimensions of linguistic structure.

First, there are a few cases of differences in the syllabic composition of the lexical items used as target words. Muong is a monosyllabic language, in the sense that "a syllable = a morpheme = a word" (Post, 2006, p. 43). Therefore, an ideal structure for the data would be for each minimal set to be composed of five monosyllabic target words of the same segmental composition, differing only in tone. However, this ideal is not always met. To deal with the difficulties in finding a complete set, in cases where it is not feasible to find the exact monosyllable needed for a complete set, two workarounds were used: (i) finding a disyllabic word which contains the needed target syllable, or (ii) finding a near-minimal set instead, relaxing the constraint on identity of initial consonants and widening the search to syllables whose initial consonant is similar to that of the other items in the set. The first solution, in fact, always came from the suggestion of the consultant(s). It is a very encouraging testimony to their engagement with the study that the native speakers understood the goal of the search and could offer such suggestions. Clearly, to the consultants who participated in the present study, this option is favoured over the option of building near-minimal sets, which was only used as a last resort. As a consequence, some target words of the minimal sets are less monosyllabic than the others from a lexical point of view. Outside context, they are not recognized as the intended morpheme, so that, strictly speaking, they have no meaning on their own, but they can nonetheless be pronounced stand-alone as a monosyllable, as part of a language game (no deep Wittgensteinian implications intended) between the investigator and the consultant.

Taking advantage of this characteristic, those "faux monosyllables" are gratefully and confidently employed for the current study. This is the case of /paj²/ in /tɤp⁶ paj²/ 'barrage' in the first minimal set, /rɔ¹/ in /ʔɤ⁵ rɔ¹/ 'idle' and /rɔ⁴/ in /paj⁴ rɔ⁴/ 'banana flower' in the second minimal set, /laj¹/ in /laj¹ tɤm⁵/ 'a kind of bamboo fence' in the fourth minimal set, and so forth.

Additionally, a few items for which a disyllabic form is provided in the relevant column of "complete word" in Tables 3.1 and3.2 are in fact just fine as independent monosyllabic words. These words exemplify the tendency towards disyllabification (or disyllabicization) whereby some words receive an increasingly frequent accompaniment (phonologically: an extra syllable) that helps disambiguate their meaning. Two cases can be distinguished here:

1. The target syllable needs a supplement (commonly a noun) to specify its exact meaning. The target item could be:

• a verb, such as (minimal set N o 5) /taj³/ in /taj³ tɔng⁴/ 'to pull kinds of bamboo by hand or by motorbike' (whereas /ɲaj²/ means 'to pull' in general, for various objects). • a noun, such as (minimal set N o 8) /ma⁵/ in /ma⁵ lɯəɲ²/ 'ell's cave hole' (otherwise, the simple, monosyllabic word for 'hole' is /hɔŋ⁵/). • a partitive noun, such as (minimal set N o 1) /paj⁵/ in /paj⁵ tʰăj²/ 'arm span'. 2. The target syllable carries the full meaning by itself but addition of a classifier allows for easier identification. This is the case of the classifier for animals, /kɔn/, in /kɔn² rɔ⁵/ 'tortoise' (minimal set N o 2), in /kɔn² ka²/ 'chicken' (minimal set N o 10), and in /kɔn² kaj⁴/ 'the female' (minimal set N o 11); or of /ke⁴/ in /ke⁴ paj³/ 'a cylindrical jar to ferment vegetables' and in /ke⁴ na⁴/ 'archery'. An additional case seems worth mentioning here: the item /kiɛŋ³/ in /ʔɤ² kiɛŋ³/ "beside" in the minimal set N o 7. The target syllable /kiɛŋ³/ can in fact be a monosyllabic word meaning "edge". However, I decided to pick the compound word instead because I found that it is easier to find a picture to represent "beside" than "edge". (The criteria to seek and select the photos will be explained in Appendix A.) In this case, the target syllable is a complement for a preposition.

To deal with this lack of homogeneity, in the experimental procedure, part of the training consisted in explaining to the speakers that the intended target items for the task are always monosyllabic, and clarifying to them exactly the intended syllable in cases where disyllabic words are involved.

It is paradoxical to note that the less the complementary syllables are obligatory, the easier it is for a speaker to forget the instruction to trim the word down to a monosyllable when speaking it out: pronouncing monosyllabic words only. This means that they are more likely to say a disyllabic word for 'chicken' (/kɔn² ka²/) and 'archery' (/ke⁴ na⁴/), which would be just fine as monosyllabic /ka²/ and /na⁴/ respectively, than for /ma⁵ lɯəɲ²/ 'ell's cave hole' or in /paj⁴ rɔ⁴/ 'banana flower', which they take care to trim down to a monosyllable as instructed. This observation provides a glimpse into the considerable importance of classifiers as a handy grammatical tool in Muong (as also in Vietnamese and a large number of languages of the area). Since the recording sessions were monitored in-person throughout, speakers were reminded of the instruction immediately after each deviation, asking them to correct by saying the expected monosyllable during the recording. The original recordings keep track of 'deviant' realizations, so that someone who wished to verify their frequency and analyze their patterns could carry out a study (somewhat like the observations about tonal 'slips of the tongue' in Yongning Na: Michaud, 2017, pp. 180-181).

A second dimension of asymmetry in the word list, which directly affects the choice of photos that serve as stimuli, is that different parts of speech are used. As will be detailed in Appendix A, finding an optimal visual prompt for eliciting speech materials constitutes a difficult task (in retrospect, I find that it was the greatest difficulty in data collection on an unwritten language). The illustrative photos method turns out to be the most effective in this situation. To be able to show by photos, the target words must be visually clear (visually tangible, as it were). Hence, as a general rule, lexical words are to be preferred over function words. One of the exception is prepositions that relate to space: those can be conveniently illustrated. Thus, in the list of words for this study, a preposition have been included in the minimal set N o 7. That is /kiɛŋ³/ in /ʔɤ² kiɛŋ³/ "beside". As mentioned earlier, this target syllable has a homonymous word meaning "edge", which is monosyllabic and a lexical word. However, we decided to pick the preposition instead because it was found easier to find an illustrative photo for "beside" than "edge".

When using function words, it should be taken into account that they are known cross-linguistically to be realized with less articulatory energy -they are phonologically 'weaker', as it were. However, the difference between content and function words in Viet-Muong might be significantly less than in most other languages. Phonologically, the function words in Vietnamese and Muong have lexical tone, like content words. This is a typological difference from, for instance, Mandarin Chinese dialects, where some function words are toneless (this is sometimes called 'light tone' or 'neutral tone' in Sinological parlance: see W.-S. [START_REF] Lee | A phonetic study of the neutral tone in Beijing Mandarin[END_REF][START_REF] Zhang | Neutral tone in Changde Mandarin[END_REF]. Phonetically, experimental research about Southern Vietnamese (based on over 60,000 syllables of conversational materials) reveals differences in duration between function words and lexical words: "function words are independently shorter than lexical words", but the difference is on an order of magnitude that is relatively limited (Brunelle, 2015). This suggests that the inclusion of function words in minimal tonal sets could be an acceptable compromise for Vietnamese (and Muong, which appears fairly similar in this respect).

On the other hand, within the range of lexical words (or content words), the possibilities of visualization are also different. A noun can usually be illustrated more easily and directly than a verb or adjective, but abstract nouns (such as happiness, patriotism, knowledge, commerce, etc.) are conspicuous counter-examples: they are almost impossible to show directly, and it is easy to get lost in the cultural meanders of allegorical representations. For instance, Figure 3.2 gives examples of efforts to illustrate the abstract nouns "patriotism" and "commerce".

Considering the materials of this study, it can be seen generally that most of the target words picked up for the word list here are pretty common and lend themselves to not-too-ambiguous visual representation. They are likely to be often used, as they belong to relatively basic vocabulary. Nouns constitute nearly 63% of the list, the rest is made up of about 24% for verbs and 12% for adjectives. There is only one preposition: /ʔɤ² kiɛŋ³/ "beside", as mentioned above. However, it is still inevitable that some words are relatively abstract and difficult to be illustrated. The word that was the most challenging is the verb /kɔ⁴/ "to have" in the minimal set N o 7. To illustrate this word, we made a detour through one of its uses: in Muong, the verb "to have" is fixed in the compound word /kɔ⁴ chɯə¹/ which means "to be pregnant", and using the image of a pregnant belly proved a satisfactory way to elicit this verb. As explained above, elicitation sessions involved a training phase where the desired target items were explained and discussed.

A third issue which could be considered a flaw of the corpus is the diversity among initial consonants, which differ in terms of voicing feature as well as in terms of place and mode of articulation. Specifically, the voiced initial consonants in the data set are:

• The alveolar trill /r/ in syllable /rɔ/ (minimal set N o 2), which is sometimes pronounced as a flap consonant /ɾ/ (there is no phonemic distinction between an alveolar trill and an alveolar flap in Muong), • The alveolar lateral approximant /l/ in syllable /laj/ (minimal set N o 4),

• The bilabial nasal /m/ in syllable /ma/ (minimal set N o 8),

• The velar nasal /ŋ/ in syllable /ŋa/ (minimal set N o 9). The use of such a wide range of initial consonants constitutes an important factor of complexity. Effects of different consonant types on the tone of the following vowel are a fairly well-documented and intensely researched topic. As a general rule, after voiceless obstruents, the fundamental frequency contour is relatively higher (in particular at the onset of voicing, towards the beginning of the vowel); whereas after voiced obstruents, the fundamental frequency contour is relatively lower (Gandour, 1974, p. 337). Onset pitch perturbations (sometimes called "pitch-skip effects") thus influence the observable fundamental frequency curves of tones, in terms of overall register but also of modulation of f 0 . The relationship between Voice Onset Time (VOT) and onset f 0 perturbations is documented in a vast literature (for instance [START_REF] Kingston | Segmental influences on F0: Automatic or controlled?[END_REF][START_REF] Hanson | Effects of obstruent consonants on fundamental frequency at vowel onset in English[END_REF]Kirby, 2018;[START_REF] Michaud | Tonogenesis[END_REF].

In the segmentation process, all voiced initial consonants are excluded, as a matter of course, retaining only the rhymes for comparison with other syllables whose initial consonants are voiceless stops (detailed in Section 3.3.1). Arguments for the division of the syllable into an initial and a tone-bearing rhyme are recapitulated in [START_REF] Michaud | A pilot study on the F0 curve of syllableinitial sonorants, comparing nasals, lenis stops and fortis stops[END_REF]. This manipulation bears a relationship with the measured duration of the tones. The transition between voiced consonants and the following vowel is not always obvious. As a general principle, I usually segment at two or three periods later from the point in the transition where I believe that the vowel has started to be present.

Of course, excluding voiced initial consonants does not amount to factoring out their effects on the following tone (their co-intrinsic properties). The diversity of initial consonants is to be kept in mind when looking at averaged curves, as in 4.1.

A final caveat about the word-list experiment is the difficulty to control whether or not the speaker runs into code switching when the target syllable has a segmentally matching syllable in Vietnamese. This issue had been avoided in the previous study when we had only two minimal sets. The two initial consonants of the minimal sets in the previous study were /p/ and /r/, which exist in Muong but not in Northern Vietnamese (except a few cases of /p/ in borrowed words, such as /pin/ "battery" from French pile, and a learned pronunciation of orthographic r as /r/ instead of /z/). Therefore, the realization of /p/ as /ɓ/ and /r/ as /z/ (their closest Vietnamese equivalent) would reveal that the speakers had somehow shifted to Vietnamese mode.

In the current study, on the other hand, the vowels and consonants of eight out of a total of twelve syllables ("segmental skeletons") are found in both languages. They are:

1. In these cases, the only phonetic/phonological difference on which we can base our intuitions about possible code-switching is tone. However, in the case of rising tones (i.e. Tone B1 in Vietnamese and Tone 3 in Muong), I do not feel at all confident distinguishing a target Tone B1 (Vietnamese) and a target Tone 3 (Muong). These tones are both glottalized, and while the Vietnamese tone tends to have strong glottal constriction whereas the Muong tone has creaky voice, they share some allophones. Whether the syllables are truly undistinguishable, or (more plausibly) some statistical difference can be brought out, is not relevant to the experimental predicament encountered: it is clear that my aural impressions are not a reliable tool to distinguish the Muong rising tone and the Vietnamese rising tone, much less to ascertain possible intermediate forms (mild cases of interference between the two languages). In such cases, where the difference between the two tone systems is not salient, code switching between Muong and Vietnamese can easily escape detection. Fortunately, the method of illustrative photos instead of reading test somewhat appears as a good way to prevent this issue.

To conclude this list of limitations on a positive note: there is no way to overcome limitations completely, but this need not be a cause for chagrin. First, for the immediate purposes of the study, the slight asymmetries and imperfections noted above do not affect the experiment adversely to an extent that would jeopardize the whole enterprise. Secondly, at an important epistemological level, sifting through asymmetries in the corpus amounts to facing constraints that stem from important linguistic and cultural facts. We are thereby led to accept these facts and to understand them. The process serves as a healthy reminder that phonetics-phonology is not a world of its own, blissfully free from ties with the rest of the universe. Reading through books and articles about phonetics-phonology, I sometimes have a feeling (shared by some others at 'fieldwork-intensive' research centres such as LACITO, LLACAN and SEDYL) that some phonologists could benefit from increased practice analyzing data pertaining to syntax, morphology and communication generally. These levels should be central in building phonological theories. As a result, I sometimes find myself uncertain about the purpose of phonologists' entreprises. The fact that doing phonology and phonetics does not always involve thorough contact with the target language may result in a drift away from social and psychological phenomena and factors that one has to face in immersion fieldwork. Learning a language and being in touch with speakers on a day-to-day basis leads one to take heed at the evidence that the lexicon, syntax, morphology, pragmatics all constitute relevant levels at the heart of linguistic systems, not to mention ethnolinguistic and social factors. Factors from all levels should be embraced as objects of study partaking in spoken communication, rather than as embarrassing impediments. Asymmetries in the data, as also exceptions and counter-evidence to phonological generalizations, need not be seen as embarrassing failures of phonology as a discipline. The ultimate goal is not to arrive at a future superior phonological analysis to account for all glitches in the data, but to arrive at a balanced linguistic understanding of language.

Carrier sentence

The use of carrier sentences is widespread among phoneticians-phonologists in order to stabilize the phonetic realization of target words. The approved order of business consists in starting out by establishing the tones' templates as realized in carrier sentences. Those can then be used as a reference for the study of coarticulation and, in due course, the full range of intonational phenomena.

When a word is spoken in isolation, there can be various effects due to the fact that the word is at the same time in utterance-initial and utterance-final position, since it constitutes an utterance by itself. Using the same carrier sentence for all target words allows for keeping the segmental and linguistic context constant. This method is commonly used in phonetic experiments, such as Michaud (2004b), [START_REF] Mazaudon | Tonal contrasts and initial consonants: a case study of Tamang, a 'missing link' in tonogenesis[END_REF][START_REF] Mazaudon | Tonal contrasts and initial consonants: a case study of Tamang, a 'missing link' in tonogenesis[END_REF]Mac et al. (2015), among many others.

In this study, the corpus includes target syllables both in isolation ("citation form") and in a carrier sentence. For each minimal set, after being collected in isolation, the target words were embedded one by one in pre-final position in the following carrier sentence:

(

1) /ja² 2SG măt⁶ to_know ____ target item ʈăŋ³/ INTERROG 'Do you know ____?'
These stimulus sentences were not presented in orthography, since Muong is an unwritten language. In order to demonstrate the carrier sentence to the speakers as an instruction on what they were expected to do in the experiment, I asked my Muong teacher to utter it. In cases where she could not be present at the recording session, the method I resorted to consisted in doing my best to pronounce the carrier sentence myself, and then translating it into Vietnamese to double-check that the speakers were fully clear what it was.

A fictional indication of context was also provided. Each speaker can (and, in a sense, must) imagine a context of some sort when saying a sentence, and as a consequence, uncontrolled variability in the suprasegmental features of the carrier sentence can occur. Not providing any indication about context therefore introduces an uncontrolled factor of variability (as pointed out e.g. by [START_REF] Niebuhr | Speech data acquisition: the underestimated challenge[END_REF]. For this reason, we provided a specific context for the sentence, so it would be easier for participants to have a reasonably clear and consistent image of a situation of communication. The speakers were instructed to imagine that they were teaching their language (i.e., Muong) to a non-native learner. Before teaching a new word, they would ask the learner whether or not he/she already knew it.

This carrier sentence had been devised and used in our previous study in 2016. We reused it for this study for at least three reasons: (i) it was safe to use a tied-and-tested carrier sentence whose advantages and disadvantages I already knew, (ii) it helps to sync the corpus of the two studies, which is handy for proper comparison, and last but not least, (iii) the carrier sentence was already familiar to those speakers who had participated in the 2016 experiment, and who also participated in the second study.

Among the advantages of this frame is the fact that the sentence, in its imaginary context, tied in neatly with the actual situation in which the investigator, who was not a native speaker, came to learn and study the dialect from local people. It helped participants remember that sentence easily and produce the speech as naturally as possible. A further advantage is that a four-syllable sentence (including the target word) proved a reasonable length to memorize and repeat. Brevity of the carrier sentence is particularly valuable when the number of target words is large. Yet another positive side of the chosen carrier sentence is that, within this frame, the target word plays the role of new, central information, which leads the word to be articulated with clarity ("hyper-articulated", to use Lindblom's term [START_REF] Lindblom | Explaining phonetic variation: a sketch of the H&H theory[END_REF]. The target word is thereby protected against phonetic shortening and hypo-articulation -phenomena that are amply attested in phonetic realizations of the other syllables in the sentence: those that are constant in the frame, i.e. the first, second and fourth (as reported in Table 3.7).

On a less positive note, using a question as a carrier sentence, as done here, does not go without saying. It brings both advantages and disadvantages. A declarative sentence seems to be favored for this kind of phonetic experiment because it is the most neutral one among the different sentence modalities. Interrogation comes with some sort of intonational flourish in many languages. "It is almost invariably the case that high or rising pitch signals the former [a question] whereas low or falling pitch, the latter [a statement]" (Ohala, 1983, p. 1). For instance, in English, as well as in many other non-tonal languages, interrogative intonation, especially in yes/no questions, tends to have an ascending pitch contour, whereas declarative intonation has a descending pitch contour [START_REF] Pierrehumbert | The Phonology and Phonetics of English Intonation[END_REF][START_REF] Ladd | On intonational universals[END_REF]. In a tonal language like Chinese or Vietnamese, however, the difference between declarative and interrogative intonation appears less straightforward because it involves interaction of tone and intonation, as well as the use of sentence-final particles that play an important role in conveying sentence mode and speaker attitude generally. The difference between declarative and interrogative intonation in Vietnamese has been widely studied, but no consensus has yet been reached on this issue. Some studies have attempted to show that there is a robust difference between declaratives and interrogatives in several acoustic correlates, such as overall f 0 , duration and intensity (T. T. H. [START_REF] Nguyen | Another look at Vietnamese intonation[END_REF][START_REF] Brunelle | Intonation in Northern Vietnamese[END_REF][START_REF] Đao | Acoustic Correlates of Statement and Question Intonation in Southern Vietnamese[END_REF]. For example, in term of global f 0 , while declaratives are found to have a slight overall declination in f 0 [START_REF] Do | Intonation in Vietnamese[END_REF]; T. T. H. [START_REF] Nguyen | Another look at Vietnamese intonation[END_REF], interrogatives are described as having a high overall f 0 range [START_REF] Hoang | Bước đầu nhận xét về đặc điểm ngữ điệu tiếng Việt (trên cứ liệu thực nghiệm)[END_REF], or a high range plus a rise which begins much earlier than the final question marker of the sentence [START_REF] Do | Intonation in Vietnamese[END_REF]; T. T. H. [START_REF] Nguyen | Another look at Vietnamese intonation[END_REF]. On the other hand, others claim that the final particles in Vietnamese, which are frequent in spontaneous speech, carry the bulk of the functional load in expressing interrogation: once they are taken into account, the associated intonational patterns appear to be largely redundant [START_REF] Seitz | Relationships between tones and segments in Vietnamese[END_REF][START_REF] Do | Intonation in Vietnamese[END_REF].

Our observations on Kim Thuong Muong's intonation suggest that the situation in this dialect is quite similar to Vietnamese as viewed through the prism of the argument mentioned above: intonational phenomena related to interrogation tend to cluster towards the very end of the utterance. Muong has a final rise in interrogatives, which is firmly grafted onto the last question markers or particles, which are really mandatory to express interrogation. (Details are to be found in a recent paper to which I contributed: Michaud, M.-C. Nguyên, and Scholvin 2021, and also in section 5.5 of this thesis.) Specifically, the final question marker /căŋ³/, employed in the carrier sentence, is the locus where salient intonational phenomena related to sentence mode appear. There is no ground for concern about a possible neutralization (or even reduction) of tonal contrasts on the syllable that precedes this particle.

Narratives

It is rather awkward to break the flow of the description of the highly controlled phonetic experiment conducted on minimal sets by introducing here a mention of spontaneous speech materials recorded as part of the same data collection campaign. It is all the more awkward as these materials are not analyzed systematically in the present study. However, they do have an important methodological goal, if only from a theoretical point of view: the ultimate goal is of course to understand the interplay of f 0 and phonation type in actual communication, not only in one highly controlled context that might turn out to be somewhat marginal in terms of ordinary, real-life communication settings. Therefore, different types of speech data were collected during this study and could be used for current or future analyses.

In addition to the isolated words and words in the isolated carrier sentence that are obtained from the minimal set experiment, I also recorded many types of spontaneous speech, including monologues or dialogues telling narratives, or singing folk songs. A complete full freedom was granted to speakers as to the topics for spontaneous speech. On the other hand, it has been anticipated that suddenly being asked to talk about a random topic without any preparation in advance would be quite awkward and difficult for them. In order to facilitate this task, some general topics has been prepared in advance to evoke speakers in case they are confused and do not know what to say. For instance, the following simple and safe topics was used as a stimulus for a start:

• The stories of the works throughout the year or year-round agricultural process • The stories of the construction of the traditional houses (nhà sàn)

• Traditional cuisine • Traditional medicine • Traditional festivals and celebrations • Childhood memories • Folk games and songs • etc. The actual topics taken up were the following: 1. The stories of the works of agriculture and farming throughout the year 2. Daily activities 3. Isolated life and work on the family's farm 4. Occupational accidents 5. How to construct a traditional houses: in the past, the houses were built with wood and with a kind of bamboo, today they are built with bricks. 6. How to cook traditional sticky rice in bamboo tube (cơm lam) 7. The process of harvesting mosses from the stream and making them into food 8. The process of picking bamboo shoots and making dried bamboo shoots (măng khô) 9. The process of making the traditional rice cake (bánh chưng) 10. How to cook and drink alcohol locally 11. Types of local fish, the local techniques of fishing and cooking fish 12. Traditional wedding: past and present 13. Festivals and rituals during the year 14. The custom of calling parents' names after their children This list was created gradually during the field trips, hence there are some topics related to the specific characteristics or situation of the region.

Most of the Muong songs that have been recorded were composed recently, so the lyrics mix a lot of Muong language and Vietnamese language. The most valuable song is the "ant song" and a lullaby performed by speakers F6, M9, F13, F14, F16 and F17. All these recordings are mentioned and detailed in the metadata (Appendix B). They will be prepared and published on Pangloss soon.

As part of this recording, we also asked all the speakers to recount the process of making "banh chung" (the traditional square glutinous rice cake). Everyone knows this process, so it was feasible to collect it. Also, using a method similar to "Pear story" (Eliciting narratives through a film), I prepared a few slides in advance to remind them of all the details. This way, they were more likely to use the same vocabulary that frequently carries the glottalized tone. This benefits a further study of glottalization on spontaneous speech.

Experiment setup

This section includes information about the participants, a brief introduction to the equipment, and the procedure for the experiment. In the appendix B, details of the types of equipment and setup as well as several problems encountered with the equipment and devices will be provided as a reference for those interested in some practical problems of recording and conducting phonetic field experiments or looking for a detailed guide to starting phonetic fieldwork.

Participants

This study comprises data from twenty speakers (ten male, ten female) past the age of eighteen. None reported any particular health or language-related difficulties. For ease of reference, each speaker is assigned an alphanumeric label, with the initial letters M or F standing for male or female respectively. I hasten to add that the use of speaker codes is by no means intended to hide the speakers' identity: they proudly agreed to be mentioned by name as contributors to the study, and their name is indicated in the metadata of the online recordings in the Pangloss Collection.

The number following the letter marks the order in which each speaker contributed to my study in its broadest sense, i.e. a process of exploring, experimenting, and documenting this language from 2015 to 2019. As a consequence, the full list provided in Table 3.3 includes not only the information of the 20 speakers just mentioned above, but also another 15 speakers. Among these fifteen speakers, some participated in recordings since my Master's study (in 2015-2016), whereas others only participated in the second data collection campaign (in 2018-2019); their data were not processed and analyzed in this thesis due to difficulties relating to the quality of the electroglottographic signal (mostly women). Additionally, the two speakers F6 and F15 did not participate in the experiment but were recorded for some folk stories and songs, which provide relevant evidence on Muong tones (and the Muong language generally) beyond the specific set of carefully controlled phonetic materials that sits at the heart of the present work. They were also assigned identifiers in order to facilitate the archiving of the whole corpus, as explained in Appendix A. Such are the reasons why there is no continuity in the identifiers of the 20 speakers in the current study's central experiment. The full metadata information on the contents collected from each participant will be listed in the Appendix B. In order to focus on the current study, we have grayed out in Table 3.3 the information of individuals whose data are not processed and analyzed here.

Recruiting native speakers for recording was an important part of the data collection process. Since the recordings were carried out in the field, with the help of my Muong teacher, who is also speaker F1, it was not difficult to find and approach local people native to the area. Most of the participants (33 out of the total 35: 20+15, as explained above) are from the three villages of Kim Thuong, and there are two speakers who come from Xuan Dai, the commune next door and speak the same dialect.

Before carrying out the experiment on a large scale, I ran the test with my Muong teacher. This had two purposes: (i) actual testing to find out problems that need to be overcome to improve the feasibility and success of the experiment; (ii) allowing my teacher to find out all about the experiment, which she would then explain to other community members when searching for participants to the experiment. Recording speech and collecting an electroglottographic signal are unfamiliar undertakings for participants; being told about the experiment by someone who had already taken it was a major asset for convincing native speakers to participate in the experiment. Such a data collection campaign is, to the best of my knowledge, simply unprecedented in the area, and confirmation from my teacher (as a local person) of the feasibility, ease of implementation, and complete absence of illegal contents did wonders to persuade native speakers to participate.

Another advantage of F1's help in recruiting speakers was that the chosen speakers' dialect backgrounds were fairly homogeneous. She knew them well as members of the same rural community, and she selected proficient speakers, rather than the occasional newcomer to the community. Accordingly, it did not come as a surprise that all participants distinguished the five tones on smooth syllables and the two tones on stopped syllables that had been identified during the vocabulary list elicitation earlier in the fieldwork. This is crucial because the experimental setup was designed for this tonal system, and cannot be applied if a consultant has a different phonological system.

A further advantage of being based in the village is that it was not difficult to find consultants for the recording. Instead of randomly selecting available subjects, we were able to take the initiative in selecting people who would be suitable for this recording and available for the task, by communicating with them and understanding how they would relate to the task. F1 and myself took care to avoid involving of consultants who would presumably have difficulty understanding the instructions; of consultants who are so eager to give advice that they become 'experiment hijackers', discussing the experiment instead of launching into it; and of consultants who have pronunciation peculiarities that make them strongly atypical. Thanks to her diplomatic skills, the screening process prevented awkward situations and saved face for all involved (an important cultural parameter throughout Asia).

On the other hand, recording at field location also implied a certain number of difficulties. Among these, the greatest difficulty (in my experience) was to find male consultants for recordings: this proved much harder than finding female consultants. Because of agricultural activities, local residents are constantly busy, especially men. The majority of men in the village are only at home twice a year, for the rice planting and rice harvest seasons. The remaining period of the year, they leave home to earn a living in the cities or to look after their family's farm in the forest. 3 Moreover, a few male speakers turned down the proposal to participate in linguistic fieldwork because they did not like the notion of being recorded: lack of confidence and fear of ridicule combined led them to turn down the offer to take part in the experiment.

Another concern is that in addition to acoustic recording, we are simultaneously recording an electroglottographic signal, which is key to the research reported here. Based on the experience from previous research in 2016, it was clear that obtaining a crisp and clear electroglottographic signal would be difficult, as it is by no means as simple to obtain as a good audio signal (especially for female speakers). Due to the specific characteristics of the throat, the Adam's apples of women are generally less visible than those of men, which creates a difficulty in correctly placing the electrodes. Moreover, the size of vocal folds and consequently the amount of variation in vocal fold contact area (monitored by the electroglottograph) is smaller in women. As a consequence, the electroglottographic signals obtained from women are frequently much weaker, with a lower signal-to-noise ratio, which makes them more difficult to analyze, to the point where some signals appear simply too noisy for reliable analysis. In order not to waste anyone's time and effort, before giving the invitation to participate in the experiment, we invited native speakers to come and do a pretest. This was possible because the experiment took place directly in the field. The speakers came on foot, or by a short bike or motorcycle ride, on the day of the pretest, at a time convenient to them. If the test was successful, we conducted the experiment right after or later on the same day, when the recording environment was sufficiently quiet. There were no problems with long drives, or taking speakers to unfamiliar surroundings, as can happen when recordings are made far from home. However, there was a number of cases where the test signal was all right but the actual recording was not as expected.

Hence the existence of participants for whom recordings were done but not used later down the line, as mentioned above and recapitulated in Table 3.3. In order to sidestep these problems in future studies, in addition to collecting basic information, I made private notes about technical glitches, aiming to uncover the reasons why recording sessions could fail to yield the desired data despite a successful pretest. These logs containing information about recording sessions as they unfolded from beginning to end proved useful for later interpretation of the data.

All in all, thanks to the kind help of local contacts (in particular the speaker F1), the data collection campaign was carried to completion. Total: 28 participants (18 women and 10 men), 29 files (the speaker M12 have recorded twice), thus 20/29 files have been processed. The detail information could be found in Tables 3.3 and 3.7.

Equipment

For the recording of the experiment, this study used the Roland 4-channel recorder which enables up to four recording channels, thus the electroglottographic signal could be recorded simultaneously with the acoustic signals. This is a high quality recording solution that linguists can bring to their fieldwork locations.

To obtain electroglottographic signal, the model used was the Glottal enterprises EG2-PCX electroglottograph. This device boast a high signal-to-noise ratio based on the use of two electrodes on each side of the throat [START_REF] Rothenberg | A multichannel electroglottograph[END_REF]. This appeared as a major advantage, since the analysis method used here (set out in Section 3.3.2) relies on the detection of peaks on the derivative of the electroglottographic signal (dEGG), which can easily get drowned in background noise. The device used in the present study has the same design as those used in studies by Nathalie Henrich [START_REF] Henrich | Etude de la source glottique en voix parlée et chantée : modélisation et estimation, mesures acoustiques et électroglottographiques, perception[END_REF], Marc Brunelle and collaborators [START_REF] Brunelle | Transphonologization of voicing in Chru: Studies in production and perception[END_REF]. This somewhat facilitates comparison across studies, by removing a factor of difference (electroglottographic hardware).

The detailed description of these equipments with the list of accompanied devices, how to setup and use them, as well as some notes on the recording environment will be provided in Appendix B.

Recording procedures: training and performance

This part is to elaborate on all the steps that were taken to accumulate the data for this study. In writing these details, I have thought about and put myself in the context of a student of linguistics who would like to explore and study new languages and dialects but does not know how to begin. Therefore, a description of the process before, during and after the experimental recording will be detailed here with some notes on the specific case of an unwritten language.

Informed consent and payment

After finding a potential local native speaker, together with my Muong teacher (who guarantees reliability), I briefly explained the purpose for which I want to make the recording, and then invited them to my teacher's house. The devices were set up and tested carefully beforehand, otherwise they would be invited in half an hour after the invitation. Once they arrived, before going into the details of the experiment, I asked them to do a brief check with the EGG equipment because this signal is not always obtained as easily as the audio signal. Especially in the case of women when their adam's apple is small and not obvious like men. Learning from a few failed recordings with the EGG signal and in order to avoid wasting everyone's time and effort, checking the EGG signal was implemented as a first step.

After confirming the possibility of recording the EGG signal, the native speakers were officially engaged in the experiment. At this point, they were presented with two forms: (i) the informed consent form as in 3.3 and (ii) the attestation of payment as in 3.4. Both forms are written in Vietnamese, so the speakers can read and verify what I present about my study and my purpose of the experiment and recording. They were informed that what they recorded that day was for my doctoral research on the Muong tone system and would be archived in the open library Pangloss. The content of the recordings contains absolutely no sensitive information. They have full discretion to decide whether or not to allow publication of the contents of their recordings and photos, or only to allow it to be studied. All recruited speakers agreed and signed the informed consent to allow me to use their contribution for my study and also for publication on Pangloss.

The certificate of payment was then shown to inform them that they will be paid for their participation. For each speaker participating in a 30-45 minute recording session (including training and performance), a remuneration of 100,000 VND (i.e. about 3.5 euros at the current exchange rate at the time), was paid. This amount is reasonable because it is higher than the average hourly income of a person in this region who is mainly engaged in agricultural work. They have been informed in advance of the amount they will receive after the recording session. This somehow encourages them to be enthusiastic and focused on the experiment and increases their tolerance to certain discomforts during the recording, such as having to wear the dual electrodes on the neck for about 20-30 minutes in the local heat of 30-35 degrees Celsius, 85-90% humidity. As soon as they have finished the recording session and signed the attestation of payment, they are paid in cash.

Training

The objective of training was to enable the consultants to perform the experiment smoothly. The purpose of the experiment was not hidden from the consultants: I explained from the beginning that my study focuses mainly on the tones of Kim Thuong Muong, and that the most important thing I expect from them is an accurate pronunciation of the tones, so that the study can bring out the contrasts between the tones, and the specific phonetic and phonological characteristics of the Kim Thuong Muong tone system. The consultants who participated in this study did not previously have a metalinguistic awareness of Kim Thuong Muong tones: for instance, they did not know how many tones there were. On the other hand, they have an awareness of differences between Vietnamese and Muong tones, reflected in statements such as that Kim Thuong Muong "does not have tones" ("không có dấu"), an observation by speaker M6 which I see as suggesting that the tone systems of the two languages are to a large extent kept distinct.

Elicitation by means of photos appears to be the best choice for a non-written language like Muong, as it avoids the use of another language (which could introduce a bias due to interference between languages) and also avoids the use of writing, which also introduces biases of its own. Using photos requires some preparation. A total of 66 photos were carefully prepared in advance and purposely arranged in a digital slideshow to facilitate the training and performance of the experiment, as can be seen in 4 which is accompanied by an explanation in Table 3.4 to show how they were employed during the training and recording. The first step in the training session is to guide the speaker to identify and become familiar with the illustrative photos that evoke the target words. Before the recording, consultants were trained. I explained photo by photo and made consultants remember which photo corresponds to which word, reminding them to say monosyllables (not disyllables), and bringing them into the imagined context that goes with the carrier sentence. Consultants were required to practise one or several times before recording: until they were able to go through the task with fluency.

It would be simplistic to expect that we would simply show the photos and the consultant would say exactly the desired word. However, as mentioned in Appendix A, not all the target words are easy to illustrate visually. There remain words that are difficult to show directly through photos, such as those in Figure A.6. In such cases, I clarified my purpose in choosing each ambiguous photo, making consultants understand and remember the indirect meaning of them. General slides as the one in Figure 3.5b were employed for this step. Since the photos of all five target syllables appear together, it helps speakers recognize the intended concepts more quickly, as they can realize that it is the same syllable but the tone is different.

A drawback of this method is that the consultants may focus on remembering (memory task). This can compete with the demands of good phonetic realization: it is hoped that the consultants can concentrate on clear phonetic realization of tone; if some items are more difficult to remember than others, a sudden remembrance after a moment of hesitation (which can be awkward or stressful for the consultant) may be accompanied by different phonetic realization. This is of course not to say that the task is beyond the ability of the speakers. After being guided through the list once or twice, item by item, they would be able to quickly remember the 66 target syllables. This experiment, in fact, did not cause great difficulty to consultants in understanding my explanation and performing as requested: the association between photos and desired target words, once explained to them, proved easy to remember. In addition, they were reassured that it is not an issue if they hesitate or make mistakes: that they would then be asked to repeat immediately, to get better results. Therefore, after training and rehearsal they were (by self-report) comfortable and (in my view) consistent in their tone realization during the actual performance.

In general, it took about twenty minutes to explain the purpose and process of the experiment, and to train and rehearse.

Performance

The recording took place right after training and rehearsal, so that the speaker's memory would be really fresh for the best performance. Recording proper usually took twenty five to thirty minutes: fifteen minutes for the minimal sets experiment (two times) and The speakers read the order number when the break page is displayed five to ten minutes for recording some narratives. There were also two short breaks, one after each chunk of experiment performance. This way, the speaker could drink water, get a short rest after an intense moment, and I could check the condition of the electrodes, making sure they were not too wet from the speaker's sweat: drying them and reapplying the electrogel. Thus, in general, the training and recording put together took about forty five minutes in total.

Due to the complexity of setting up the equipment, the training and recording always took place on the same day. In 2018, with the assistance of Thi-Hang Dinh (Đinh Thị Hằng), a colleague at the Institute of Linguistics in Hanoi, we efficiently conducted the experiment in one week with three to four native speakers per day.

The equipment was set up in the morning. Potential speakers were invited from the day before, or right in that morning. While I was checking the EGG signal obtained from the speaker(s), Dinh could help me train them. During the recording, I could focus on controlling the recorder and the EGG equipment, checking the sound during the session while Dinh showed the slides and pointed at the illustrative photos for the speakers to recognize the desired word as learned at training. Based on that lead, the speakers were required to speak aloud from minimal set N o 1 to N o 12 and from minimal pair N o 1 to N o 3. For each minimal set, they first spoke the five target syllables in isolation before repeating them once more in the carrier sentence. Exactly the same routine was performed with 3 minimal pairs. The slideshow of photos (as explained in Table 3.4) are organized for this purpose. The instruction with photos during experiment allows for (approximative) control on tempo, avoiding large changes in speech rate (speeding up or slowing down) that often happen in this type of tasks (for a review, see [START_REF] Niebuhr | Speech data acquisition: the underestimated challenge[END_REF].

A check-list was prepared so as to follow the same procedure consistently with all speakers. It is admittedly pedestrian, but it arguably saves a lot of trouble: having the sequence of basic gestures neatly arranged with no real risk of oversight frees the investigator's attention to focus on meaningful interaction with the consultants, without sudden bursts of stress in the midst of a recording session.

At the start of the session:

•

After a recording session

Once the recordings were completed, the speakers were asked to sign the payment attestation and were paid immediately thereafter.

The last step of data collection is to transfer the audio files from the recorder, saving them on several backups (one on my computer, one on a USB stick and one on a hard drive) to keep them in complete safety in the short run. In the field, backups were created on hard drives: there was not enough bandwidth over the mobile 'phone network to sync gigabytes of data on remote servers. Back at LACITO, the data were stored on servers until the process of preparing annotations came to fruition, at which point the audio files were made public (in 2021). The electroglottographic files were not made public immediately, so as to preserve a window in time when I can continue to prepare publications on this data set. Interested colleagues are welcome to get in touch to set up collaborations on this data set. On the other hand, if the electroglottographic files were simply made available under a Creative Commons license, it would be perfectly lawful for colleagues to use the data without prior notice, only acknowledging the source of data, but it would be awkward for me. The electroglottographic files are already in the archive and making them public is now a matter of a few clicks for the archive managers. I am committed to taking this step without unreasonable delays.

To facilitate data management, a copy of the original files was created and renamed with the following file naming conventions: "crdo-MTQ_KTM_[SpeakerUID]_[Content]". All file names are in capital letters and the underscore is allowed as a separator. The crdo-MTQ_KTM part is fixed. These identifiers follow conventions used in the Pangloss Collection [START_REF] Michailovsky | Documenting and researching endangered languages: the Pangloss Collection[END_REF], an archive of language recordings in which the data is hosted. The identifier for each document begins with <crdo-> (the acronym of the former name of the Cocoon archive, which hosts the Pangloss Collection: Centre de Ressources pour la Documentation de l'Oral) followed by the ISO code of the language in the Ethnologue catalogue of languages (the code for Muong is MTQ). KTM is the abbreviation for the target language, Kim Thuong Muong. The next two pieces of information are the speaker ID and the file content. The speaker ID can be found in the second column of Table 3.3. The file content is marked as "MINIMALSET" if it is the experiment recording, whereas if it is a narrative, a short keyword is used to reflect its broad topic. For instance, the data of speaker M1 was renamed from the original file as:

• crdo-MTQ_KTM_M1_MINIMALSET.WAV for the file of experiment of minimal sets • crdo-MTQ_KTM_M1_FOLK-GAMES for the file of narratives about folk games • crdo-MTQ_KTM_M1M7_CUSTOMS for the file of a dialogue between speaker M1 and M7 talking about some traditional Muong customs These renamed files are the files that are used further down the line for all processing and analysis operations. Needless to say, the original (master) files were retained for reference, without any processing after recording.

Then, the information of all the files were stored in a metadata file. This key step allows for relating relevant pieces of information together: the file name (modified name and original name), speaker information, recording time, duration, storage location, file quality, as well as various notes.

As emphasized relentlessly by archive curators and information management specialists, rich metadata are crucial to keep the data well-organized. The more information we can store immediately after recording, the easier it is for us to organize and work with the data later, because it is much easier to do this in the field than to bring data back to the lab and try to retrieve metadata from memory. Accordingly, the perspective of data preservation and dissemination was taken into account from the earliest stages. Metadata were gathered at the stage of data collection: writing down information that goes without saying at the time, but which may become difficult to access (or lost altogether) if not put to writing in good order. Data management was handled in an Open Science spirit, keeping in mind the goal of practical usefulness of the data to other users in future.

Data processing

Figure 3.6 shows the basic procedure that was applied to the data set of twenty speakers to obtain quantified results: values of f 0 and O q , as plotted in numerous graphs in Result chapter.

For the most part, the initial input materials for this process are audio files obtained from the minimal set experiment. They are first segmented and annotated (using the Sound FoRgesoftware) to obtain the annotated electroglottographic file in monochannel format and the Regions List indicating the time codes for each token, together with its unique identifier (UID). These are the two inputs required by PeaKDet, a semi-automatic tool for estimating f 0 dEGG and O q dEGG from the electroglottographic signals. After a meticulous (and time-consuming) verification process, summarized in the algorithm shown as Figure 3.13, the data matrix from PeaKDet is used to plot figures (by means of scripts) to visualize the result. This process will be elaborated step by step in the following sections.

In my experience, during the long process of extracting parameters from the electroglottographic files, it is most practical for all the files to be put in one place, with an online file storing service, to ensure that files are kept safe while being processed and can be reverted back to the previous version at any time in case of an incidental error. This prevents unfortunate computer crashes or artifact errors during the analysis process. Otherwise, such glitches can be very costly in time and effort.

Data segmentation and annotation with Sound Forge

The first step in the process is to take the data (with the modified name) from each speaker to segment each word (both the target word and the frame word) into tokens and annotate them with a unique identifier (or UID), so that they can be analyzed in the next step, item by item. This step is carried out on Sound FoRge, a professional digital audio editing software. The version used is Sound FoRge10.

The bit-depth of the recordings is 24-bit, which allows for recording at a safe recording level, leaving headroom for sudden increases in voice intensity that may happen at any point during speech. Digital volume amplification was then conducted: the volume of the audio channel was normalized only once for each session, to preserve comparability across items within the same session. (The magnitude of amplification was on the order of 6 to 18 dB depending on sessions.) Normalization was conducted using Sound FoRge, before data annotation. The audio was not subjected to any other processing, such as filtering.

The general principle of segmentation: based on electroglottographic signal and audio signal

Using a 4-channel recorder yields files that are not in the stereo format, which (at the time of writing) is most widespread in digital audio. Each audio files has four channels: (i) acoustic signal of native speaker from headset microphone, (ii) acoustic signal of native speaker from regular microphone (referred to colloquially as a "table mic" because it can be placed on a table), (iii) electroglottographic signal of native speaker, (iv) acoustic signal of interviewer (instructor or cooperator). The four-channel signal can be handled without difficulty with Sound FoRge.

The audio signal is not the subject of data analysis and parameter calculations in this study, but it was used as the main cue for segmentation since the transitions in the electroglottographic signal are not as clear-cut as those in the audio signal: as a sweeping statement, it can be said that segmental events do not appear as such in the electroglottographic signal, which is recorded at the voice source (the larynx) prior to filtering by the vocal tract. For segmentation, the audio signal offers key evidence to recognize the boundary and transition between the initial consonant and the rhyme, especially based on the shape change between periods of the audio signal.

The three most fundamental principles of segmentation are: 1. (Figure 3.7): Segment the whole syllable if the initial consonant is voiceless and take only the rhyme if the initial consonant is voiced [START_REF] Michaud | A pilot study on the F0 curve of syllableinitial sonorants, comparing nasals, lenis stops and fortis stops[END_REF]) 2. (Figure 3.8): The segmentation of a token must have a minimum of three cycles, otherwise the token is considered to be absent as a distinct interval. 3. (Figure 3.9): In cases where the rhyme is completely missing, it cannot be segmented. It is then marked (as a time marker on Sound FoRge, rather than as an interval; it appears as a single orange vertical line) at the beginning of the missing syllable. It is then stored in the Regions List, but not processed by PeaKDet. 4. (Figure 3.10): Phonologically voiceless consonants that are phonetically voiced (sonorized) are treated as voiced consonants, i.e. the voiced portion corresponding to the initial is excluded at the stage of annotation, so that only the rhyme part is taken. In detail, the segmentation and annotation task consisted in indicating the temporal beginning and ending point of each syllable rhyme, for the target syllables and also for each syllable of the carrier sentence. Tone is non-segmental and it normally stretches over all of the syllable's rhyme part. Therefore, to measure glottal parameters relative to tone, one needs to annotate the rhyme part, excluding the initial consonant if it is voiced. One can take in the whole syllable if the initial consonant is (phonetically) voiceless. Examples are shown in Figure 3.7.

In the case of a voiced consonant, at the boundary between the consonant and the vowel, it is recommended to exclude the first two or three cycles of the vowel to be sure to take only the rhyme. This is to say that the indication of the beginning was placed a little later than where the transition can be recognized. My experience confirms that it is more difficult to segment the rhyme of a voiced fricative consonant (e.g. /ʝa2/), and a trilled consonant (e.g. /rɔ/), than a voiced nasal consonant (e.g.

/ma/).

For tone analysis, a rhyme part should have at least three glottal cycles (as Figure 3.8). In fact, one cycle (i.e. the interval between two closing peaks on the derivative of the electroglottographic signal, as explained in section 2.4) is sufficient for calculating one f 0 dEGG value, making for well-formed results. However, the decision to choose a minimum of three cycles appeared safer because data processing involves averaging across tokens. Averaging tokens with just one or two cycles with others that have more than ten times more appeared as a possible cause of interpretive conundrums down the line. Since the emphasis of the present study is on the modulation of the f 0 dEGG (and other parameters) in the course of tones, it appeared safer to reserve the study of borderline cases of elided or quasi-elided syllables for later.

During annotation, there were two special treatments for some uncommon cases, as illustrated on Figures 3.9 and 3.10.

(i) In a few cases the rhyme at issue is not present at all as a distinct temporal interval, so that it is not possible to assign it a beginning and endpoint -there is no identifiable portion of signal (not even one cycle) corresponding to the rhyme at issue. For this case, instead of a Region, I just place a Marker in Sound FoRge, with the mention "missing syllable", as in Figure 3.9. The item is then deleted (manually) when exporting the Regions List from Sound FoRgefor processing of the electroglottographic signal. (More details on the Regions List and how it is used further down the processing line will be presented in section 3.3.2.) (ii) Because of coarticulation and hypoarticulation, there are a few cases in which a voiceless initial consonant has its manner of articulation modified: loss of closure for stops, realized phonetically as weak voiced fricatives (spirants in the sense of André [START_REF] Martinet | La Description phonologique avec application au parler franco-provençal d'Hauteville (Savoie)[END_REF]. This phonetic phenomenon is called spirantization, a tendency that had Ferlus, 1982. This is not an issue for annotation: in that case, I just handle the rhyme the usual way, excluding the initial consonant, as in Figure 3.10b. These phenomena do not have a direct bearing on the target items: they only occur on frame syllables, not on the target syllable, which is generally hyperarticulated rather than hypoarticulated. For instance, issue (i) only occurred on the first syllable /ja2/ when the speaker tends to shorten the carrier sentence during a series of repetitions; and issue (ii) only occurred to the last syllable /ʈăŋ/ because it is the end of sentence, so these syllables tend to be pronounced voiced.

At the same time as the beginning and endpoint of each rhyme was indicated, I also labeled every token. Labels are strings of numbers that consist in the concatenation of three part, referred to as AA, 5 B and C.

Position AA is the UID of the target syllable as provided in second column of Tabs. 3.2 and 3.1. It is, in fact, the order in which the target syllables appear in the list of materials. Therefore, position AA runs (i) from 01 to 40 for target from eight minimal sets, (ii) from 41 to 60 for four near -minimal sets, and (iii) from 61 to 66 for three checked minimal pairs. Position B relates to the position of the syllable rhyme within the sentence. Each sentence has four syllables, hence: value 1 means first token /ja²/ (2sg), value 2 means second token /măt⁶/ 'to know', value 3 means third token "target syllable", and value 4 means fourth token /ʈăŋ³/ (inteRRog). Besides, the value 0 is used to label the target syllable in isolation.

The last value in the scheme, position C, indicates the repetition of the token. As this experiment is performed twice, the value 1 indicates the first time, and the value 2 is for the second time.

A summary of the scheme is provided in Table 3.5. The precision of the annotation is key to precision in the quantitative values obtained at the next step: electroglottographic analysis, to which we now proceed.

In addition, there are two additional conventions: 1. xAA: good token but out of place since there was more repetition than necessary. 2. z: problematical token with disfluency, hesitation, background noise, overlapping speakers, etc. These annotations are not used for the next step of data processing with PeaKDet, thus they are deleted from the Regions List like the case of missing word. Later, in the data archiving work, they are all stored in the XML file in order to give as detailed as possible of the actual state of the corpus.

By understanding these labeling conventions, we can easily retrieve the content and information of any UID token in the data. For example:

• Item with UID 3632 means: the target syllable /ma5/ in carrier sentence, second time. For each speaker's data, a total of 660 tokens (full size, without missing syllables) are segmented and labeled. The exact status is shown in Table 3.7. The last step that needs to be carried out on Sound FoRgeis the extraction of two files after the anotation is accomplished: (i) the electroglottographic signal (on the third channel) as a mono .wav file, (ii) the Regions List as a .txt file (as Figure 3.12).

The electroglottographic signal can be extracted easily on Sound FoRgeby simply selecting the desired channel, pressing the key combination ctrl+C to copy it and then ctrl+E to paste it into a new file, and finally saving it (ctrl+S) as a .wav file in the input folder for the next processing with PeaKDet.

In the mono annotated electroglottographic file just obtained (or it is the same in the 4-channel annotated file), I continue extract the Regions List by selecting in the Sound FoRgetoolbar (as displayed in Figure 3.12): Edit > Regions List > Copy onto Clipboard. Then, using Notepad++ to paste it and save the file as a .txt file in Figure 3.11: Mono electroglottographic .wav file: the second input of PeaKDet the same folder where the electroglottographic file has been stored . This is also the time to remove from the Regions List all annotations for missing words, out-of-place words and problematical words that were mentioned earlier. They are always preserved in the original annotated .wav files for later archiving.

Analyzing the electroglottographic signal: how the PeakDet script was applied

After annotating all 20 speakers' data, the next step is to analyze the electroglottographic signal using the PeaKDet tool in the MATLAB computing environment to estimate f 0 dEGG , O q dEGG (by four methods), and several other parameters as detailed in Table 3.6.

PeakDet: an implementation of an analysis method based on peak detection

There exist several scripts for analysis of the electroglottographic signal. That created by Nathalie Henrich [START_REF] Henrich | On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation[END_REF]) is designed for the singing voice. It is based on autocorrelation, and is not designed to handle portions of voicing that are close to the onset or offset of voicing. In speech, however, voicing is often interrupted and resumed. This difference in the input signals led linguists to write algorithms that are suitable for tracking glottal parameters in spoken language. Peak Detection (henceforth PeaKDet) is a MATLAB6 script for calculating f 0 dEGG and O q from electroglottographic signals. It is available online from the website of Tools for Electroglottographic Analysis: Software, Documentation and Databases (link: http://voiceresearch.free.fr/egg/index.html). It is also available from COVAREP, a Cooperative Voice Analysis Repository for Speech Technologies (link: http: //covarep.github.io/covarep/). COVAREP is an open-source repository of advanced speech processing algorithms hosted on GitHub: researchers in speech processing can store original implementations of published algorithms on COVAREP Degottex et al., 2014. The latest version is provided in a Github repository (link: https: //github.com/MinhChauNGUYEN/egg/tree/master/peakdet_inter). The advantage of this repository on Github is that one can easily download the script, use it under the LGPL-3.0 license. Then, during the process of applying the tool, if there are difficulties or suggestions for improvement, it is possible to "open an Issue" on Github to communicate directly with the author. For instance, during this study, I created a bunch of Issues to suggest improvements to PeaKDet (as can be seen by following this link: https://github.com/alexis-michaud/egg/issues). Having privileged access to the code maintainer (being my supervisor) was very helpful in solving some of the practical issues that arose when applying this tool to my data. Specifically, the addition of a display of glottal cycle numbers in the dEGG signal figure was a great improvement in facilitating the verification of closing and opening glottal cycles. This improvement saved me a lot of time in processing the data with PeaKDet. More details on this topic will be provided later in this section.

PeaKDet is designed for semi-automatic measurement: the results for each token are verified visually, and some parameters can be modified to adjust to the input signal.

PeaKDet shows the position of the first and last detected glottis-closureinstants on the electroglottographic signal and on its derivative, so that the user can appraise visually whether the full interval of voicing has been taken into account or not. This is useful in cases where the amplitude of the signal varies considerably within the portion of signal under analysis. (Excerpt from the PeaKDet user guide.) This current study used the PeaKDet tool for analyzing the electroglottographic signal in order to study Kim Thuong Muong's tone system. The fact that the estimation of glottal parameters is not 100% automatic makes it all the more important to be as explicit as possible about decisions that I made in the process of semi-automatic processing. Hence, the paragraphs that follow provide a step-by-step description of how I applied the PeaKDet script for my data, what improvements were made to PeaKDet as compared to the version that I used for my Master's work, as well as how I dealt with some particular, unusual issues that arose when dealing with certain data visualization, data analysis, and numerical integration (Website: http://www.mathworks.com/ products/matlab/). It comes complete with all the bells and whistles that one would expect from a full-fledged computing environment, in particular a comprehensive and convenient documentation manual. The PeaKDet script worked well with MATLAB 2014a, which I used in my study. Other versions, both earlier and later, have not yet been verified. recordings. Hopefully, this piece will be useful to beginners to get some information on the experience of applying PeaKDet to a given data set.

Step-by-step description of the process of analyzing the electroglottographic signal with PeakDet

Use of PeaKDet assumes minimum knowledge of MATLAB. The script does not have a graphic user interface: it requires some interaction using the MATLAB command line, such as opening and running a script (.m file), setting the path to the right folders, and saving the work in progress. Elementary knowledge of this type is sufficient for a beginner to be able to apply PeaKDet without going into how the script works. This is the stage I was at for my Master's study, and it proved manageable. In the course of the present thesis work, I started to be able to understand the script: to follow how PeaKDet actually operates, step by step. It is much better thus, not only because I can now debug some simple problems by myself, but also because I now understand clearly how PeaKDet encounters some problems that are related to the characteristics of the electroglottographic signal. Then I can describe the issue on Github and ask for a solution. Therefore, it is highly recommended that the user has a basic knowledge of the MATLAB language. The diagram in Figure 3.13 summarizes the steps of the implementation of PeaKDet, dividing them into four basic steps: (i) indicating the path to the two input files, namely the electroglottographic signal and the time codes in a text file (a Regions List) exported from Sound FoRge; (ii) conducting a verification of fundamental frequency values, f 0 dEGG ; (iii) conducting a verification of open quotient values, O q dEGG ; (iv) saving the output. The first and fourth actions are executed only once, respectively at the beginning and at the end of the process of analyzing one electroglottographic recording. The second and third actions are repeated in a loop: once for each token in the file. Such are the main operations in PeaKDet, which have not changed across versions. These steps are described one by one in the paragraphs that follow.

As a preparation, a prerequisite is to prepare the two input files and to download PeaKDet on Github, i.e. Peakdet_inter (from here: https://github.com/ alexis-michaud/egg).

Importing the data

The first thing to do is, of course, to open MATLAB, then run PeakDet_inter. There are two ways to run PeakDet_inter.

1. In the CuRRent FoldeR Window, click on the folder icon with a green downward arrow like the red rectangle numbered 1 in Figure 3.14. A new window requesting "Select a new folder" will appear so that the user can navigate to the location of the PeakDet_inter folder. Once the PeakDet_inter folder is selected, all the files in that folder, including the file peakdet_inter.m, will appear in the CuRRent FoldeR Window (as the red rectangle numbered 2) and the address leading to that folder will be updated in the directory path (as the red Note that if PeakDet_inter is run in the second way, it is also necessary that the PeakDet_inter folder is open in the CuRRent FoldeR Window, otherwise MATLAB will not be able to find the path and run the command. Therefore, the second method is mentioned here only to provide all the possibilities to execute PeaKDet, but it is more practical and faster to execute it with the first method.

When PeaKDet has thus been called, two dialog boxes appear one after the other to prompt the user for the location of the two inputs: (i) the EGG file and (ii) the Regions List, as shown in Figure 3.15. The user's work is to direct PeaKDet to the folder containing these files and to select them by double-clicking.

Default analysis parameters

At the same time as the input requests, some default settings are displayed in the Command Window as shown in Figure 3.16b. These parameters can also be adjusted later on, in case it is found that the values initially chosen are not suitable in view of the characteristics of the data under analysis. For example, some men's data have a much lower f 0 dEGG range than women's, so the upper threshold for f 0 dEGG , which is set to 500 Hz by default, can be changed to 300 Hz or 350 Hz. Changing this setting is among the options proposed at the stage of f 0 dEGG verification. It is possible to make an adjustment for each token. This is a change from the previous (2016) version, in which these settings were set as shown in Figure 3.16a.

In particular, for the three parameters in Figure 3.16a, the three frequent choices for my 2016 data were:

• Parameter #1: selecting 3 to use a value calculated by the barycentre method for peak detection in case of multiple closing peaks. • Parameter #2: setting 300 Hz for male voices and 500 Hz for female voices as a f 0 dEGG ceiling in the detection of double peaks. • Parameter #3: selecting one among the values from 1 to 3 for the number of points for dEGG smoothing, depending on the level of noise in the signal. In the version of PeaKDet used here (version 1.0.5, released in 2019), these three variables are set by default to the following values:

• Parameter #1: as previously, use the barycentre method for peak detection in case of multiple closing peaks. • Parameter #2: The f 0 dEGG ceiling is set at 500 Hz as a threshold for the detection of double closing peaks. • Parameter #3: the smoothing step for the derivative of the electroglottographic signal is set at 3, i.e. a window of a total length of seven data points (three before and three after the data point itself). This modification is suitable for beginners who do not really go into the way in which PeaKDet operates: the above default settings are safe and can be applied to most data, including cases where the quality of the data is not really good (with noise) or if there are many instances of multiple closing peaks. Each default setting comes with an instruction that tells the user where to change the setting inside the script: see Figure 3.16b. Of course, users can only avail themselves of these functionalities if they understand the problem that causes PeaKDet to not work on their data or to give a misleading output. The user also has to understand the function and options of each parameter to modify it to suit his/her data.

Graphic displays

When PeaKDet has received the path to the EGG file and its corresponding Regions List file (containing the time codes of each portion of signal to be analyzed), it proceeds to the next step. The tokens are processed in turn in a loop to detect open and closed peaks in the dEGG signal, from which the parameters (f 0 dEGG and O q dEGG ) are calculated.

With each token, the operations performed automatically by PeaKDet include: (i) smoothing and derivating the signal, (ii) detecting closing and opening peaks, (iii) calculating parameters, and (iv) storing values in a 10-column7 × 100-lines matrix. The visible part, to which the user has access for each token after the automatic processing, consists of four plots:

• Figure 1 also called ddEGG signal. This is also a change from the 2016 version as in the previous version there were only the first three plots. The ddEGG signal was added to address one of the issues raised regarding erroneous detection due to the occasional presence of a 'hill-shaped' pattern at the opening phase in glottalized pulses. The second derivative of the EGG signal offers a way to address this problem. The details of this issue will be provided at a more appropriate place in this thesis in Chapter 5 where we discuss some specific cases of glottal opening peaks.

At the same time that those four plots are provided at once in four new FiguRe Windows, MATLAB will provide some information about the current processing token in the Command Window (as in Figure 3.18), namely:

• UID of the token. In the example in Figure 3.18, the UID of the token is 101.

According to the conventions used for the data set, this UID indicates that this is the target syllable /paj⁵/ in isolation at first performance. • The status of the EGG signal: (i) first smoothed and derived as plotted in Figure 3 (e.g., Figure 3.17c), (ii) second smoothed and derived as ploted in Figure 4 (e.g., Figure 3.17d). • The values of f 0 dEGG . Thanks to this information, we can know the number of automatically detected glottal cycles and the specific value of each detected glottal cycle. For example, in the example being used here, the number of cycles is 50 and the specific f 0 dEGG values of each cycle can be seen in Figure 3.18 which is also plotted in the green line in Figure 3.17a.

User verification of f 0 dEGG

In the Command Window, the next part following the information on the values of f 0 dEGG are instructions on the options of f 0 dEGG treatment (as can be seen in the bottom part of Figure 3.18). Figure 3.17: A demo of four initial plots after automatic processing of a token by PeaKDet. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation.

Figure 3.18: Together with four plots as in Figure 3.17, the display of the current processing token on Command Window with identification information, f 0 dEGG information and f 0 dEGG processing options. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation.

f 0 dEGG , as explained in section 2.4, is computed from closing peaks because "The fundamental period is given by the position of the first maximum, which corresponds to the time between two consecutive closing peaks" [START_REF] Henrich | On the use of the derivative of electroglottographic signals for characterization of nonpathological phonation[END_REF]Henrich et al., , p. 1328. A closing peak is identified as a good peak when it is well-defined with a single peak, as shown in figure 3.20.

At this stage, the user's task consists in looking at Figures and f 0 dEGG values, following the instructions of PeaKDet to make choices as appropriate in view of the results. If all the values are correct, type 0 (zero) to retain the result and move to the next step. If some of the glottal cycles went undetected, or extra cycles were erroneously detected, there are five options:

1. enter 1 (one) to change the settings for automatic detection; 2. enter 2 to split one of the automatically detected cycles into two (by visual detection of a cycle not detected by the script); 3. enter 3 to merge two automatically detected cycles; 4. If you wish to correct some of the f0 values manually, enter 4; 5. If the coefficient is correct but the initial/final cycle(s) must be suppressed, enter 5. In order to know which option to choose and use, the user has to look at the dEGG signal (i.e., Figure 3) to verify if all the glottal cycles are detected correctly or not. To facilitate this task, it is necessary to use three functions provided in the toolbar of the Figure 3 Window (as shown in Figure 3.19b), including: (i) zooming in (magnifying glass icon with plus sign), (ii) zooming out (magnifying glass icon with minus sign), and (iii) moving the position (hand icon), in order to check every detected cycle. This operation is also carried out in exactly the same way when checking the opening peaks.

As shown in Figure 3.19b, when the signal is zoomed in, we can see the detected glottal cycles more clearly and easily based on two information:

• The vertical dashed red lines indicate precisely where the closing peaks are detected and the two solid red lines indicate the first and last detected glottal cycles. This means that the interval between two lines is counted as one glottal period. Inverting the time of each interval gives the f 0 dEGG value of a period. • The numbers at the top and bottom of each interval indicate the order of each glottal cycle. Based on this, it is easy and rapid to find out which cycle(s) is (are) detected or undetected erroneously, and then to enter this order number in the Command Window for a modification. Note that after each modification, the glottal cycles will be recounted and the order number of the cycles will be changed. These features were not offered in the PeaKDet 2016 version. This is really an important improvement as it speeds up the analysis process and improves accuracy. Before these improvements, I had to manually count each cycle to know which period needed to be adjusted. It was taking me over a year to process data from ten speakers. And after this upgrade in the current PeaKDet, it only took me about three more months to complete the remaining ten.

In my experience, if all the closing peaks are precise and are well detected, the f 0 dEGG curve (green) in Figure 4 will be continuous without sudden breaks. To save time, before verifying the closing peaks in dEGG signal, I first look at f 0 dEGG curve in Figure 4. If detecting unusual value(s) that cause the curve to break abruptly, then I will refer to dEGG signal in Figure 3 to verify how the PeaKDet detected at that cycle or cycles.

In terms of options for modifying the f 0 dEGG outcome, the following will explain and give an example to demonstrate when each of the above options should be chosen and what should be done for each option.

Thanks to analyzing a large amount of data, I had the opportunity to go through and use all the options offered in PeaKDet. All the examples here were chosen are the most clear and typical example for each option should be used. In reality, in some complicated signals we have to decide which options are the most optimal and maybe even combine several options to deal with one problem. Gradually, such experiences arise after dealing with more specific cases. The more I use PeaKDet, the more I understand how it works to use it more effectively and get more accurate results.

The first option is selected when all the closing peaks are detected correctly and no modification is required. The other options (second through sixth) are used when some of the glottal cycles went undetected, or extra cycles were erroneously detected.

Note that the options from the second to the sixth (options to modify) can be selected many times and do not have to be in a certain order. Only when option 0 is selected does this process end. One then moves on to the next step: the verification of O q dEGG . In my data, closing peaks are mostly well-defined with a single peak. Therefore, in most cases, I can quickly select the first choice by typing "0" (zero) in the Command window) to indicate that no correction is necessary, and go on to the next step.

Figure 3.20 shows an ideal example, where all the closuring peaks are clear, resulting in good detection. The corresponding f 0 dEGG curve is continuous, without breaks: see Figure 3.20b.

On the other hand, let us return to the example of Figure 3.19: token 0101, target syllable /paj⁵/ in isolation, data from speaker M1. It can be seen that the last three f 0 dEGG values decrease dramatically. However, this is not a detection error of PeaKDet. Referring to the dEGG signal of these cycles, shown in Figure 3.19b, we can observe that all cycles from the 56 th to the 58 th have precise closing peaks and are correctly detected. In fact, this is a frequent phenomenon in this language. When the word is spoken in isolation, it tends to be realized with a tense/hard offset, involving a final glottalization. The three long glottal cycles (especially the last one) at the end of the syllable exemplify this phenomenon. So the detection results can safely be validated.

The second option: "enter 1 (one) to change the settings for automatic detection" This is useful in cases where some the glottal cycles went undetected. An example is found in data of speaker F21, token with UID 0501: syllable /paj⁴/ in isolation, first performance.

In this case, it is necessary to adjust the value used as a threshold for the detection of closing peaks, so that PeaKDet can detect all periods (or leave out the spurious peaks, if extra periods were detected erroneously). To illustrate the case where a change in the threshold value is necessary because of undetected peaks, Figure 3.21a shows the location of undetected peaks in the dEGG signal, and Figures 3.21b and 3.21e shows the difference in the resulting f 0 dEGG curve before and after threshold correction.

The third option: "enter 2 to split one of the automatically detected cycles into two (by visual detection of a cycle not detected by the script)".

Example taken from data of speaker M14, token UID: 2001, target syllable /laj⁴/ in isolation, first performance.

Since this example is a token carrying the glottalized tone, it is difficult to say to what extent these six small symmetrical oscillations in the middle of the syllable reflect a technical problem (a difficulty for the electroglottographic device to monitor vocal fold contact area for some technical reason) and to what extent they reflect a phenomenon related to glottalization. On the one hand, these cycles occur in the middle of the rhyme, a position where glottalization is typically (and phonologically) present in Tone 4 in Muong. On the other hand, it is not a typical glottalized signal, but rather looks similar to a soft offset of voicing. Considering the audio (DOI: https://doi.org/10.24397/pangloss-0006798#W39, we can perceive a constriction in the middle: there is no relaxing at all. These small, symmetrical oscillations might reveal an interesting case in which, I suppose, the vocal folds have been completely adducted. during this period, but the surface of the vocal folds continues to vibrate with small oscillations. Therefore, it was somewhat difficult for me at first to decide whether these oscillations should be divided into cycles or not. It is the case that there is strong glottalization in the middle of the rhyme; seen in this light, changing the parameters in the script in a way that makes the f 0 dEGG curve look more continuous can appear as a bad idea, as it irons out, as it were, a specificity in laryngeal behavior which the medial dent in the curve brought out forcibly. However, finally the choice was to split them. Since periodicity is not lost altogether, it appears more appropriate that the f 0 dEGG curve should look continuous as in Figure 3.22g, than artificially assigning the entire span of low-amplitude electroglottographic signal to one extremely long glottal cycle (which would clearly be an artefact). Furthermore, the O q dEGG result confirms that the phonation type does not switch to creak (phonation mechanism 0), since most values are above 50%, that is, in the range of modal phonation. The O q dEGG values surrounding the unusual f 0 dEGG are not lower (if anything, they are higher than what surrounds them). Therefore, it would be very implausible for the fundamental frequency to drop below 10 Hz for just one cycle.

The fourth option: "enter 3 to merge two automatically detected cycles (if visual detection reveals a spurious cycle)".

Example taken from data of speaker M14, token UID: 3502, syllable /kiɛŋ⁴/ in isolation, second performance.

The fifth option: "If you wish to correct some of the f0 values manually, enter 4". Example taken from data of speaker F3, token: 152, UID: 1602, the target syllable /laj⁵/ in isolation, second performance. This is a dangerous option that I would not recommend in cases where one or more (e) EGG signal. After the six small oscillations are split into six cycles.

(f) dEGG signal. After the six small oscillations are split into six cycles.

(g) Result of f 0 dEGG (green) and O q dEGG (blue and orange). After the six small oscillations are split into six cycles. other options can be chosen instead. I used this option for one token in data of speaker F3 (token: 152, UID: 1602) which has a very serious signal error. Instead of splitting the small oscillations, I simply manually modified the unusual f 0 dEGG values in some cycles so that they were close to the surrounding values. However, when plotting the results, there was an error in this token, so I suppose it may be because I chose this option when treating f 0 dEGG .

The sixth option: "If the coefficient is correct but the initial/final cycle(s) must be suppressed, enter 5."

Example taken from data of speaker M14, token: 10, UID: 0142, syllable /ʈăŋ³/ the fourth word of carrier sentence, second performance.

This option is employed when the first or last period(s) are out of the range found in the rest of the rhyme: they have widely different value(s) from the others. This case can easily be corrected by suppressing that/those period(s).

The token shown in Figure 3.24 has non-continuous f 0 dEGG toward the end at position (3.24b) because PeaKDet detected three closing peaks after the rhyme had ended (3.24a). This is not an artefact: the shape of the dEGG signal indicates clearly that four small closing peaks are present, i.e. the glottis closes at these points, and there is quasi-periodic fluctuation in vocal fold contact area. Three of these four periods were detected by PeaKDet, i.e. the 31 st to 33 rd cycles.

However, for the purpose of the present study, a crucial point is that these small closing peaks take place after phonation has ended: the four symmetrical oscillations that occur at the end are typical of vestigial vocal fold oscillation at 'soft' (nonglottalized) offset of voicing. It would be wrong to include these small oscillations along with the other normal glottal cycles. The unexpected f 0 dEGG value at cycles 31 st , at about 220 Hz (3.21b), is clearly an artifact, and should be removed. Therefore, I suppressed the last three values. The actions to treat this case are illustrated in Figure 3 To deal with this case, the second possible way is to use the option of changing the threshold of peak amplitude for automatic detection so that PeaKDet will not detect these extra peaks.

A final clarification concerning f 0 dEGG estimation by PeaKDet is that this script makes no "sanity check" on the f 0 dEGG results: no check of quasi-periodicity of the signal is performed. The script detects closing peaks, and the value offered as "fundamental frequency" is the inverse of the period. This can be very misleading in cases of period doubling (referred to in Section 5.2 as multiply-pulsed creak): the pattern that repeats itself contains three closing peaks on the electroglottographic signal, but the values reported in the "f 0 dEGG " column wrongly suggest that there are two simultaneous pitches (as in diplophonia), one high and the other lowish. This peculiarity requires care in the interpretation of the obtained data: thus, a speaker's average fundamental frequency as obtained by averaging all f 0 dEGG values obtained through PeaKDet is likely to be slightly higher than that obtained using autocorrelation-based tools. This limitation is not likely to be of any consequence to the results reported here but needs to be kept in mind in case the results reported in the present study are re-used in future work (as one hopes may happen, in an Open Science perspective).

User verification of O q dEGG

Whereas f 0 dEGG is calculated based on closing peaks, which in the great majority of cases are well-defined (often with a unique peak), estimating O q dEGG requires the detection of opening peaks, which often runs into difficulties due to imprecise peaks: either cases where no peak stands out clearly, or cases where two or more peaks are present (multiple peaks). The search for opening peaks is even more difficult in the case of nonmodal phonation, such as when voicing transitions into creaky voice. This makes user verification of O q dEGG a delicate business, which is not so similar with verification of f 0 dEGG : it requires more than just a few adjustments for peculiar situation.

PeaKDet will ask the verification of O q dEGG after the verification of f 0 dEGG has finished. At first, it will process automatically and offer O q dEGG calculated in four different ways:

1. maxima8 on unsmoothed dEGG signal (displayed as orange squares); 2. maxima on smoothed dEGG signal (displayed as orange stars); 3. barycentre of peak on unsmoothed dEGG signal (displayed as blue squares); 4. barycentre of peak on smoothed dEGG signal (displayed as blue stars)

The methods are divided into two sets:

• Detection of the local minimum on the signal in-between two closure peaks. This method is applied twice: on the unsmoothed dEGG signal, and on the smoothed dEGG • Analysis of the shape of opening peaks and calculation of a barycentre of the detected 'peaks-within-the-peak', giving each of the peaks a coefficient proportional to its amplitude. Again, this method is applied twice: on the unsmoothed dEGG signal, and on the smoothed dEGG. The display of the 2021 version (1.0.5), which can be seen in many figures in the f 0 dEGG section such as Figure 3.21, is better than that of the version I had used previously (in 2016), as shown in Figure 3.25. It uses fewer colors and fewer marking symbols, and they stand in a logical relationship: the colors show different methods (orange for local maxima, blue for barycenter) and the marking symbols distinguish results from the unsmoothed signal (stars) and smoothed signal (squares).

The verification of O q dEGG involves two steps: (i) selecting among the outputs of the four methods, by choosing one in four, and (ii) visually verifying the O q dEGG result of that method.

In simple cases, all open peaks of the item are well-defined peaks, which means that there is a single, well-defined negative peak inside each period. As a result, the four methods yield almost identical results of O q dEGG , as shown by four coincident curves. In such non-problematic cases, we can choose any method among the four, and there is no need for further correction of results before moving on to the next item. The example of good closing peaks in Figure 3.20 also presents the case where all opening peaks are well-defined and should be kept by type '0' in the Command Window.

However the simple cases are few. The majority of my data required more complex verification, due to imprecise peaks in dEGG signal. 'Imprecise peaks' can mean several things, as can be seen in Figure 3.28: (i) there can be several negative peaks during the opening phase, with none of them standing out as a main peak; or (ii) there can be no well-marked opening peak at all. Consequently, the result of four methods will be different. The difference is often conspicuously visible as a broad scatter (a clear mess) of O q dEGG curves, as in Figure 3.26. A careful decision needs to be made as to which method is appropriate, and which values among the set yielded by this method should be retained. By a visual verification of opening peaks in the dEGG signal, we can choose a method which accurately reflects the well-defined peaks. Then, the values corresponding to imprecise peaks need to be suppressed.

This does not appear unfeasible, but requires great care, and an investment of time. For instance, the analysis of total 660 items for data of each speaker, it took at least three days for careful examination and decision-taking. A practical tip to facilitate this stage is to use an extended screen (as in Figure 3.27) so that we can have two windows at the same time: (i) one screen shows four plots for verification on the signals, and (ii) one screen shows the Command Window for executing selections on f 0 dEGG and O q dEGG after verifying on the signals. This is very convenient and time-saving, especially when processing a large amount of data.

Figure 3.28 is a good example illustrating a case where there are both precise and imprecise opening peaks, and thus I will able to explain how the verification step of O q dEGG carried out in general.

In this example, the opening peaks in the middle (from cycles 11 to 24) are precise with one prominent peak in each cycle, as can be seen in the zoom in of Figure 3.28a. This corresponds to good consistency across the four methods of calculating O q dEGG at the bottom of the figure 3.28b in these cycles.

On the other hand, the fit across methods is lost at both ends (beginning and end of the rhyme). This is caused by imprecise opening peaks that can be classified into two kinds: (i) the first two peaks at the beginning without any precise opening peaks and (ii) the rest of the beginning at cycles 3 to 10 and cycles 25 to 30 at the end with more than one peak standing out, which is impossible to identify which is the real opening peak.

The treatment for this case is as follows: First, I decided to select the method of maxima on the smoothed signal by entering '1'in the Command Window. Then, all values from 1 to 10 at the beginning and from 25 to 30 at the end were suppressed by indicating '1:10' and '25:30' also in the Command Window.

More generally, the basic processing in this step includes:

• The interface of PeaKDet: is shown as Figure 3.27 with four plots of (i) f 0 dEGG and O q dEGG , (ii) EGG,(iii) dEGG, and (iv) ddEGG in four separate figures, and simultaneously in the Command Window the instructions and the requests for O q dEGG verification are displayed as Figure 3.30. • User's action #1: First, consider the figure of the results of f 0 dEGG and O q dEGG to check whether the calculation of the four methods is consistent. Second, select and zoom in on the figure of dEGG signal to verify all the opening peaks and pay particular attention to the part(s) where the methods do not match, or even differ widely. The next step is to decide which method to choose by considering the one that can detect the majority of the precise peaks. Usually, I have chosen either (i) the method of maxima on smoothed signal (typing 1) in the case where there is one and only one precise opening peak in each period; or (ii) the method of barycentre of peaks on smoothed signal (typing 3) in cases where there are multiple peaks during the opening phase but one really prominent peak can be detected and the others are close. Therefore, the results of the four methods will not be too different and justified to be close to the exact result. The acceptable difference used in this study is 5 %. Figure 3.29 provides some specific cases where selecting the method of the barycenter of the peaks on the smoothed signal (typing 3) is highly recommended. • User's action #2: after a method has been selected (in command #1 of Figure 3.30, the next step is to suppress all imprecise peaks that are visually detected in the figure of dEGG by specifying in the command #2 the order number(s) of these cycles that are marked at the top and bottom of each cycle. Those suppressed values are set to zero, by convention, and displayed in the command window as well as in a new plot of only the O q dEGG values for the selected method. When all imprecise peaks are suppressed, type '0' to finish and move on to the next token. In this semi-automatic procedure, decisions are left to the user's appreciation. This may appear as a less safe path than fully automatic measurement, as it raises issues of reproducibility and replicability. Whether another researcher takes up the same data set (reproducing the study) or collects new data (replicating the study), they will not arrive at the same exact results, since there is a stage of decision-making that relies on subjective appreciation. Importantly, the values yielded by the four methods are all stored in the results matrix, and none is deleted during manual verification: instead, the values selected by the user are stored in a different column in the results matrix (the tenth and last column). It therefore remains possible, at any point in data processing further down the line, to compare the values chosen by the user to those yielded by fully automatic detection, or to compare the four methods. In other words, manual verification adds information to the results, and does not remove any.

Output: After all the tokens have been thus inspected and processed, i.e. when f 0 dEGG and O q dEGG have been calculated for all items in my data, PeaKDet saves the entire workspace in a ".mat" file, as a final output. The results of analysis are in a three-dimensional matrix called <data>, containing one two-dimensional matrix (hereafter referred to, for short, as a sheet) per token analyzed. It means that the <data> matrix for each speaker should contain 660 sheets, corresponding to 660 rhymes.

Each sheet presents the main results of a token in a single matrix including 10 columns x 100 lines. The contents of the 10 columns are explained in Table 3.6. The 100 lines are the default space corresponding to a maximum of 100 glottal cycles of one syllable rhyme. This length is automatically extended in cases where a syllable rhyme contains more than 100 cycles (Muong, like Vietnamese, can have really long syllables). As presented in Table 3.7, six out of twenty data files have more than 100 lines, which means that six of the twenty speakers produced at least one syllable rhyme with more than 100 cycles. The lines are extended up to 178 in the data of speaker F10 (who thereby wins the title of the speaker with the longest rhyme).

Plotting and data visualization

Visualization of results

After obtaining the final result (in .mat file) from PeaKDet for 20 speakers, the last step of this data processing is to plot the data in different ways to serve for the visualization and analysis of the result. Thanks to the available plotting scripts in my The open quotient values retained after user's verification % master study, I could easily and quickly use the same scripts (as can be consulted here, in M.-C. Nguyên (2016, pp. 117-126)) with a few modifications so that they could be applied to the current data and run for all speaker data at once. The available scripts were served for plotting the curves average f 0 dEGG and O q dEGG of the tone system in a graph by several ways, including 5 types of graph:

1. average f 0 dEGG curves with standard deviation 2. average O q dEGG curves with standard deviation 3. average f 0 dEGG curves with no standard deviation 4. average O q dEGG curves with no standard deviation 5. average f 0 dEGG curves in semitone. All these types of graphs are plotted and available for the current data. However, due to the huge amount of figures, for the sake of a simple and efficient observation, we only provide in the Result chapter the figures of the average f 0 dEGG and O q dEGG curves with standard deviation by 20 speakers, as can be seen in Figure 4.1. In addition, new plottings of data normalization for were added. The tone system (the five smooth tones) normalized by gender (one graph grouping data from the 10 men and one for the 10 women) and normalized over the entire group: 20 speakers (Figure 4.2). The formulas used to obtain the relative values of f 0 dEGG and O q dEGG are taken from the 2008 study of the Tamang language by Mazaudon and Michaud (2008, p. 238). The following two (simple) equations are therefore reproduced from this study with permission.

The formula used for obtaining relative f 0 values (in semitones) is the following in Equation 3.1, where F REL is the relative value (in semitones), F TARGET the measurement on the target syllable (in Hertz) and F FRAME the measurement over the frame (in Hertz):

F REL = 12 × log( F TARGET F FRAME ) log(2) (3.1)
O q values were also recalculated, relative to a mean value across speakers. In view of the strong cross-speaker differences in mean O q , shown in Table 4.1, O q values were converted using the following formula in Equation 3.2, where O q TARGET is the measurement for the glottal cycle at issue, and O q MEAN the mean O q value across speakers, obtained by averaging across all the syllable rhymes in the corpus, carrier sentences included.

O q REL = 100 × ( O q TARGET O q MEAN -1) (3.2)
The same formulas are also applied in figure 4.3 not only for 5 smooth tones but also for 2 checkered tones which are plotted separately to clarify the two sub-systems.

In addition to these sets of figures for the entire tone system, we also have three other types of graphs to examine the glottalized tone in particular and in more detail:(i) a raw display, i.e. one curve corresponds to one item ( 3) of f 0 dEGG and O q dEGG across speakers. These figures are simply produced by using the plotting functions available in MATLAB such as boxplot and scatter plot.

Data archiving and publishing

Long-term data preservation is central to the work reported in this dissertation. The underlying principles are currently grouped under the notion of Open Science, and gather increasingly strong support from policy makers and academic institutions, but they were familiar to linguists long before the notion of Open Science entered common usage. The long quotations below recapitulate decisive reasons to give data curation a central place in the context of field research.

Primary outputs of field research (lexicon, transcripts and interlinear glossed text collections, and their associated media) need to be coded and preserved. Long-term access to these data is addressed by the establishment of archives that also act as the locus for training and advocacy for well-formed data. (Thieberger and Jacobson, 2010, p. 147) The field records linguists produce are meant to endure and to be available to the people we record and their communities, as well as to fellow researchers well into the future. Archiving is no longer something we do at the end of our fieldwork. It is apparent now that it should be integrated into everyday language documentation work and that it is a crucial aspect of documentary linguistics. (…) Recent technological advances have pointed to the importance of planning data management and workflow for ethnographic recording. (…) [W]e must, right from the moment of recording, be concerning with making good documents and placing them into a suitable archive for storage and discovery. Thus, we can distinguish archival practice, a process resulting in well-formed archival data, from archival storage in a repository. (Thieberger and Jacobson, 2010, p. 148) In a perspective of progressive archiving, initiated since the early stages of data collection, the data were curated with a view to an early deposit in an archive ensuring long-term preservation: the Pangloss Collection, itself a part of a nationwide archival setup [START_REF] Michailovsky | Documenting and researching endangered languages: the Pangloss Collection[END_REF]. Data were deposited in 2020-2021, and thus received a Digital Object Identifier (DOI) in time for me to use these identifiers to propose links from the PDF version of the present work to the data. (On the process of assigning DOIs to linguistic data, and their relevance to linguistic research, see [START_REF] Vasile | Le Digital Object Identifier, une impérieuse nécessité ? L'exemple de l'attribution de DOI à la Collection Pangloss, archive ouverte de langues en danger[END_REF]

A bird's eye view of the full data set for the main experiment

As a conclusion to the present methodological chapter, this section is devoted to a brief summary of the full data set for the main experiment in this study: recapitulating its design and providing an inventory of the collected materials. This will give the reader an overview of the basis that is available for this study.

Speech materials: This study is based on the recording (acoustic signal recorded simultaneously with EGG signal) of twelve minimal sets that distinguish five tones in smooth syllables (including eight complete minimal sets and four near-minimal sets) and three checked minimal pairs which distinguish two tones in checked syllables. The list of these sets and pairs is provided in Tables 3.1 and 3.2. Each item in this list has an associated target syllable that is a monosyllable. Therefore, we have a total of 66 target syllables.

Carrier sentence: In order to stabilize the phonetic context, a standard method is to ask speakers to pronounce the target words in a carrier sentence. As set out in Section 3.1.2, the carrier sentence is a short sentence constituted of 4 words: three frame words and one target word. The process of a recording is that the speaker says all the target words of each set in isolation, then repeats them with the carrier sentence, and so on from the first to the twelfth set and from the first to the third pair. The whole procedure is then repeated a second time.

Sequence of an experimental session: In the real performance of recording sessions, speakers were required to speak aloud from the minimal set N o 1 to N o 12, from minimal pair N o 1 to N o 3. For each minimal set, they first speak the five target syllables in isolation before repeating them once more but in the carrier sentence. This is exactly the same with 3 minimal pairs.

The total corpus (per speaker): Figure 3.31 recapitulates the total corpus of this study. Not only the target words but also the three frame words of the carrier sentence are annotated and processed. Thus, for each speaker, we have a total of 660 items, of which 264 items are target syllables and 396 items are frame syllables. A more detailed list of the amount of materials is given in Table 3.32. In some cases, the maximum number of items is not reached because some frame words are missing, as speakers tend to shorten the carrier sentence during a series of repetitions. The most serious case is in the data of the speaker F10. For some technical reason, we made a pause but mistakenly did not press the record button to resume, so the last part of The actual status of the data of each speaker is summarized in Table 3.7. There are a total of 26 participants, 28 data files (F1 and M12 perform the experiment 2 times) twenty of which have been processed.

Beyond this quick inventory focusing on the main experiment used in this study, a list of recorded files is provided in Appendix B at the end of this volume.

The Kim Thuong Muong tone system: observations based on fundamental frequency and open quotient curves averaged by speaker

The experimental setup and analysis method set out in the previous chapter, involving an experimental routine performed by 20 speakers, now puts us in a position to set out quantitative results about the tone system of Kim Thuong Muong. 1In this chapter, the figures representing the results will be set out in the following order:

• The tone system (the five smooth tones) as realized by the twenty speakers, shown speaker by speaker in the H z scale (Figure 4.1) (and the figures in semitones (Figure D.1) for f 0 dEGG parameter are provided in Appendix D as a reference); • The tone system (the five smooth tones) averaged across speakers. First normalized by gender, with one graph grouping data from the 10 men and one for the 10 women. Then normalized over the entire set of speakers: a third graph averaged over all twenty speakers (Figure 4.2); • A comprehensive look at the full tonal system, including the two checked tones alongside the five smooth tones2 (Figure 4.3); • A particular description on the glottalized tone of each speaker, shown in two ways: (i) as a raw display, where one curve corresponds to one item (Figure 4.4), and (ii) a comparison on the distribution (Figure D.2). Figure 4.1 provides curves of f 0 dEGG and O q dEGG averaged by speaker, laying a basis for a large part of the analyses that follow. The data from the ten female speakers are provided first, in sub-figures (a) to (j), followed by data from the ten male speakers in sub-figures (k) to (t). Let us now look at these results, taking a quick tour of the individual results of all twenty speakers while keeping an eye on the cross-speaker averages in Figure 4.2. The averaged f 0 dEGG curves of each individual speaker are displayed in absolute values (i.e., on the Hertz scale). For producing cross-speaker averages, on the other hand, the raw f 0 dEGG values are converted into semitones (relative values), as a simple means to achieve normalization across speakers. The formulas used to obtain the relative f 0 dEGG values (in semitones) and the O q dEGG values were adopted from Mazaudon and Michaud (2008, p. 238). This method is also similar in its essentials to that used in our earlier study of the Naxi language (Michaud, Vaissière, and M.-C. Nguyên, 2015).

The representations shown in Figure 4.1 for twenty speakers were obtained from the analysis of twelve minimal sets illustrating the five tones (full detail on data collection and processing was provided in Chapter 3). Within the sub-figure for each speaker, the left-hand side represents f 0 dEGG curves, and the right-hand side represents the O q dEGG measurements at the same time points.

The average values of f 0 dEGG and O q dEGG shown in Table 4.1 are used as reference values to describe and evaluate all the results in this chapter. The values were obtained by averaging all values for syllable rhymes (target syllables and carrier sentences) for a given speaker, as a rule-of-thumb reference value of the speaker's mean f 0 and O q , for purposes of elementary normalization. The ratio of excluded O q reflects the proportion of O q values that were manually excluded at the stage of semi-automatic data processing, following a procedure set out in Chapter 3. It provides an indication on the overall representativity of the O q values shown in the figures: thus, the fact that 88% of all measurements had to be excluded for speaker F20 means that estimation of O q was exceptionally difficult for this speaker, and the curves cannot be considered as accurate as those for the other speakers, with exclusion rates ranging from 4.7% to 36.3%.

Let us start out from observations based on examining Figure 4.1. In general, the f 0 dEGG and O q dEGG curves of 20 speakers demonstrate agreement on the basic tonal patterns briefly summarized in Table 2.6 of Chapter 2.

Fundamental frequency

In terms of fundamental frequency, the tone system appears relatively symmetrical.

Tone 1 is phonetically flat, located around the middle of the speaker's range. In contrast to this tone, Tone 5 is another flat tone but at a higher pitch level. Indeed, it is the highest tone in the system, with f 0 dEGG values consistently at the top of the speaker's range. Tone 2 and Tone 3 are characterized by falling and rising contours respectively. The amplitude of the rise in Tone 3 is sometimes not as great as that of the fall in Tone 2, as one would expect if one assumes a small effect of declination in f 0 (an effect found in declarative utterances). Last but not least, Tone 4 has a pattern that looks symmetrical along the time scale. It has a descending-ascending contour with offset values close to the onset values, and a glottalized portion in-between. (120 syllables in total: 24 items for each tone)

Open quotient

In terms of open quotient, according to my studies on this tone system so far (M.-C. Nguyên, 2016; M.-C. [START_REF] Nguyên | A glottalized tone in Muong (Vietic): a pilot study based on audio and electroglottographic recordings[END_REF], it appears safe to say that the typical patterns of O q dEGG curves can be separated into two parts. In the upper part, the O q dEGG curves of four tones (Tone 1, Tone 2, Tone 3, and Tone 5) overlap. They are consistently above 40-50%. In contrast, in the lower part of O q dEGG range, we have only Tone 4, on its own. The O q dEGG curve of this tone plunges from initial mid-range values (already lower than the four other tones) to the very bottom of range.

A large amount of O q dEGG values of Tone 4 tokens had to be excluded, due to the problem of unclear opening peaks on the derivative of the electroglottographic signal (an issue dealt with in the Method chapter (3)). The retained values are lower than 30% and can reach extremely low values: below 15% in some speakers. These values offer telltale evidence of the presence of creaky voice (phonation mechanism zero according to the classification of Roubeau, Henrich, and Castellengo 2009).

Duration

In terms of duration, there is no great difference among the five smooth tones: less than 0.05 seconds. Tone 1 is the longest tone in most speakers, reflected in a jut-out of the green line on many figures, which is most noticeable in the cases of F3 (4.1a), F10 (4.1d), F12 (4.1e), F19 (4.1h), M7 (4.1m) and M14 (4.1t). In contrast, the other flat tone, Tone 5, appears as the shortest among smooth tones. The average curve for Tone 5 is shorter than that of the other tones in many speakers, although only by a handful of milliseconds. A fairly clear difference can be observed in the cases of speakers F7 (4.1b), F9 (4.1c), F10 (4.1d) and F12 (4.1e), where Tone 5 is shorter than all other tones. It seems as if there were some kind of relationship between pitch level and duration here. The rising tone (Tone 3) is generally shorter than the falling tone (Tone 2). In the case of the three speakers F20 (4.1i), F21 (4.1j) and M12 (4.1r), there is a pairwise difference in the offset of Tone 1 and Tone 2 versus Tone 3 and Tone 5. Each pair terminates at the same f 0 level and also at the same point in its time course. It can be noticed that the length of the glottalized tone is, on average, very close to that of the other tones: in this specific experimental condition, Tone 4 cannot be told apart from the others on the basis of its duration. This is different from Vietnamese tone B2, also a glottalized tone, which is about half shorter than the other tones in its system. In Kim Thuong Muong's system, glottalization does not appear to affect the duration of the tones, so Tone 4 ends up at the same offset time as the other tones.

Were one to look for fine phonetic detail in patterns of duration, Tone 4 should probably be placed in the same category as Tone 1 and Tone 2: a set of tones that are a bit longer in comparison with Tone 3 and Tone 5.

The relatively longer duration of Muong Tone 4 as compared with the Northern Vietnamese tone B2 can be accounted for in at least two (complementary) ways. First, there is a difference in the location of the glottalization. Whereas Vietnamese B2 has a final glottalization that constrains duration (by sharply interrupting the syllable), Kim Thuong Muong has a medial glottalization, followed by a return towards modal voice at the end, so the glottalization event does not interrupt the syllable. Second, the nature of the glottalization is different. Whereas Vietnamese B2 is characterized by a glottal constriction (Michaud, 2004b;Kirby, 2011), the phonation-type specificity of Kim Thuong

Muong Tone 4 is an event that has creaky voice as its canonical characteristic. The constriction in Vietnamese B2 is physiologically a gesture of strong adduction of the vocal folds; it is definitely the factor that makes this tone shorter than the others. By contrast, the Kim Thuong Muong Tone 4 is not shortened by its glottalization, which does not have a strong degree of constriction. Due to the time required for a shift to creaky voice (the time for the irregular pulsation pattern to set in), it could even be that the presence of creaky voice in Tone 4 would tend to lengthen the syllable carrying that tone, rather than shorten it. In some cases, such as speakers F9 (4.1c) and F17 (4.1g), Tone 4 is the longest tone.

But to put the hypothesis to the test, one would need to examine the tone system in a greater diversity of contexts than was done in the present work: in the context under study, the target item is in focus, all syllables are really long, and syllables carrying Tone 4 do not stand out systematically in terms of duration, as was pointed out above.

Thus, in view of the present experimental results, duration by itself does not appear to play an important role in contrasts among the five tones of smooth syllables. On the other hand, duration differs greatly between smooth and stopped syllables. The two checked tones, i.e. Tone 6 and Tone 7, are only about half as long as tones in smooth syllables, as can be observed in Figure 4.3. This can be ascribed to the influence of obstruent codas. Final /p/, /t/, /c/ and /k/ are phonologically unspecified for voicing (there is no voicing opposition among final consonants in Kim Thuong Muong), but these codas are phonetically unvoiced, and appear to exert the full shortening effect that is cross-linguistically associated with final voiceless stops.

The duration of syllable rhymes is diverse across the 20 speakers, with an average of 0.28 seconds. Speaker F3 (4.1a) has the shortest syllable rhymes, with only 0.20 seconds. This value is roughly equal to just half the duration of the tones of F9 (4.1c), the speaker who produced the longest rhymes in this experiment. The rest range from 0.25 seconds to 0.30 seconds. Interestingly, there is no straightforward influence of rhyme duration on the clarity of the general tonal picture: the figure showing the tone system of F3 (who produced the shortest rhymes) is one of those that present the clearest tonal contrasts. Admittedly, 0.20 seconds is already a fairly sizeable duration for a syllable rhyme: not an extremely brief duration, and not a particular challenging setting for realizing a phonetically complex tone.

Diversity across speakers has been mentioned at various points in this paragraph (devoted to duration), as also in the two preceding paragraphs (devoted to fundamental frequency and open quotient, respectively). Let us now turn our attention to crossspeaker similarities and differences in tonal spaces, confronting headlong the rich patterns of language variation found even in controlled, elicited materials as studied here.

Cross-speaker similarities and differences in tonal spaces

The separate plots for the twenty speakers effectively show a highly rich and diverse range of realizations of the tonal system, against a clear background of common phonological characteristics, reflected both in f 0 dEGG and in O q dEGG . It would of course be inappropriate to say that some speakers have a better tonal system than others, but there is no harm in making subjective comments so long as those are clearly labeled as such. With this precaution, one can point out that, based on the criteria of clear spacing between tones and neat modulation of contour tones, the tonal systems of speakers F3 (4.1a), F9 (4.1c), F20 (4.1i), M9 (4.1o) and M11 (4.1q) give an impression of being well behaved. Any of these five plots could serve as a textbook example of the Kim Thuong Muong tonal system, in the unlikely event of this language variety ever being taught in a language school.

Among male speakers, M14 has somewhat similar patterns with M9 (the latter being one of the group identified as the 'well-behaved five'). Their glottal behavior verges on timidity (by its limited range), but nonetheless draws with full consistency a clear, smallish, delicate-looking tonal picture in which Tone 4 stands out by some consistent irregularity indicative of the presence of creak. To the extent that creak, which is a departure from periodicity, can ever be described as being controlled, these speakers' Tone 4 can be said to have cogently controlled creak (under experimental conditions which, it should be noted, are by themselves conducive to consistent behavior).

Among female speakers, F7 and F10 also have curves with similarities to the 'wellbehaved' patterns, although within somewhat broadened ranges: longer rhymes (especially for F9), and more noticeable creak for F7, which does not fully abate by the end of the rhyme.

In general, most speakers have their f 0 dEGG tracings well separated across tones. There are nonetheless several speakers whose tonal spaces are really narrow and small compared to the others. This is the case for speakers M7 (4.1m), M8 (4.1n), M10 (4.1p) and M13 (4.1s). Their tones only occupy a small part of the overall space in the figure -which embodies the fullest range used by the set of twenty speakers, so as to be able to plot all the subfigures within the same ranges.

How these observations on differences in overall f 0 dEGG range found in these figures relate to the speakers' actual use of their personal ranges (their laryngeal possibilities) remains to be investigated in future. The figures for average standard deviation for f 0 dEGG in Table 4.1, which include the syllable rhymes in the carrier sentence, are fairly abstract and general, and not straightforward to interpret. The speakers listed above (M7, M8, M10 and M13), whose tonal spaces are the smallest, also have lowest standard deviation in f 0 dEGG . But the rough estimate provided by pooling all the data together and calculating mean standard deviation in f 0 dEGG also places speaker M14 in the same range (standard deviation of about 25 Hz). More fine-grained tools, teasing out the effects of parameters such as the amount of glottalization in a speaker's data, will be required for future work relating the speakers' f 0 dEGG ranges in this experiment with broader patterns used in these speakers' prosodic strategies in actual communication.

In terms of tonal space, compared to women, men tend to have a narrower range of pitch. Among 20 speakers of this study, it can be observed that the males' ranges only span an average of about 100 Hz, usually from 70-80 Hz to 170-200 Hz. The range is narrowest in the cases of speakers M10 (4.1p) and M13 (4.1s): from 50 Hz to 110-120 Hz only. An exception is speaker M12 (4.1r): his range of pitch is wide (from about 120 Hz to 300 Hz).

The range for women is much wider, with an average of about 220 Hz. It is convenient, as a first approximation, to distinguish two subsets for women's tonal systems. The first subset groups cases where the range is from about 50 Hz to 250 Hz: such is the case for most female speakers. The range is maximal in the cases of speakers F9 (4.1c) and F20 (4.1i): from 50 Hz to 300 Hz (i.e. a range of roughly 250 Hz). A second subset consists of cases where top values are also at about 250 Hz, but bottom values are much less extreme: around 100 Hz, so that the overall range is lower. Needless to say, this rough grouping into two sets does not tell the full story: speaker F13 (4.1f) is an outlier, in that her bottom end of range is above 100 Hz but her upper end of range is at about 350 Hz, which makes for an overall wide range (a 250 Hz span).

The overall difference between men and women is predictable since male vocal frequency is lower than female vocal frequency [START_REF] Laver | The phonetic description of voice quality[END_REF][START_REF] Catford | Fundamental problems in phonetics[END_REF], with average f 0 dEGG on the order of 100 Hz and 200 Hz respectively.

One way to look at these gender differences is to consider that women have more space to "play" with their tones, with generally wider spaces and clearer modulations. The figures for speakers F9 (4.1c), F13 (4.1f) and F20 (4.1i) look like cases in point: all of the tones are visually very clear, well distinguished from one another, and with salient, clear modulations for glissandos.

However, when examining these differences in speaker ranges, it should be kept in mind that absolute frequencies in Hz may not always be the most suitable way to represent fundamental frequency in speech. Conversion to a logarithmic scale has been argued to correspond best to listeners' intuitions [START_REF] Nolan | Intonational equivalence: an experimental evaluation of pitch scales[END_REF]. When converted to relative values (specifically, to semitones, the interval between two adjacent notes in a 12-tone scale), differences in Hz come out fairly differently: the same distance in Hz will be twice larger, in semitones, if the frequencies at issue are on the order of 100 Hz, than if they are on the order of 200 Hz.

Thus, conversion to semitones facilitates cross-speaker comparison, especially across groups with different overall ranges of f 0 dEGG : here, women and men. An additional reason for looking at the data through the lens of the semitone scale in the present study is that, as compared with the Hz scale, it brings out the lower part of the fundamental frequency range, as compared to the higher part. That is an attractive property for a phonetic study that pays special attention to Tone 4, the lowest in the tone system under investigation. Therefore, Figure D.1, which can be observed in Appendix D, plots the same data as in Figure 4.1 (f 0 dEGG for all speakers), but in semitones instead of Hz. Now returning to the description of individual speakers' curves, and of patterns of cross-speaker similarities: there are at least two things that make the tone systems of speakers F9 (4.1c), F13 (4.1f) and F20 (4.1i) appear especially neat and clear.

The first thing is the rise of Tone 3. In these three speakers, Tone 3 can be observed with an exemplary falling-rising contour. The fall of the first half puts into sharp relief the steepness of the rise of the second half, which is not as salient in the other speakers. Especially in comparison with the Tone 3 of speakers F3 (4.1a) and M13 (4.1s), which almost overlaps with their Tone 1. Indeed, although I have not yet done a formal perception test, in my experience, I have no difficulty distinguishing Tone 1 from Tone 3: what is difficult for me is to distinguish Tone 1 from Tone 2.

A possible explanation for this, I think, is that in terms of pitch perception, the mid-low pitch of Tone 1 brings a perception that is more similar to a fall than to a rise. In what I feel to be a parallel situation, I usually perceive a global rise in Tone 5 (the highest tone), although what can be observed in the f 0 dEGG contour of this tone does not substantiate the perception: it is usually a flat tracing (with a fall at the very end).

The second point which makes for a display that is particularly clear visually in these speakers' data is the sharp rise of Tone 3. That observation raises the issue of the correlation between f 0 and O q . Open quotient and fundamental frequency are not linked by a straightforward relationship of correlation: for instance, at the end of Tone 2, f 0 dEGG decreases while the O q dEGG tends to increase; and for Tone 1, the slight rise in open quotient towards the end does not correspond to an increase in f 0 dEGG : instead, it is interpreted as reflecting the gradual decrease in the degree of vocal fold adduction towards the end of phonation. In the case of Tone 3, the sharp rise in O q dEGG over the last third of the syllable corresponds to the rising part of the f 0 dEGG curve. It could be that, as f 0 rises, the phonation mechanism changes to mechanism II ('head voice') and the vibrating part of the vocal folds becomes smaller, with the higher open quotient values characteristic of phonation mechanism II. This observation will be taken up again when discussing Tone 5.

The second, and equally important, thing that affects the clarity of the tonal space is that the f 0 dEGG curve of Tone 4 stands out by a clear dip in the middle, which is more U-shaped than V-shaped. This determines the bottom values set in the display (the y axis of figures), since this is the lowest tone of the system. In most cases, among the 20 speakers present, it is easy to tell apart the red line from the rest of the system, since it has half or more of the pitch range to itself. It alone occupies a separate space: even the highest points of this tone (located in positions of onset and offset) are lower than all the other tones.

By visual inspection, the seven speakers who possess the best-distinguished Tone 4

are F3 (4.1a), F7 (4.1b), F9 (4.1c), F19 (4.1h), F20 (4.1i), M9 (4.1o), and M11 (4.1q).

Impressionistically, those can be considered as ideal contrasts for Tone 4. The other cases are less distinct: the range of pitch is narrower. This is the case of speakers F10 (4.1d), F12 (4.1e), M5 (4.1l), M7 (4.1m), M8 (4.1n), M10 (4.1p), M13 (4.1s) and M14 (4.1t).

In these cases, the f 0 dEGG curve of Tone 4 is still located at bottom, but much less distant from the other tones, and the V-shape or U-shape is less steep. The discussion of this issue will be continued and detailed in the section on glottalization (4.3) later in this chapter, where the glottalized tone is the object of close scrutiny. In general, it can be observed that there is great diversity in terms of tonal space across the 20 speakers. The greatest difference is found between speakers F9 (4.1c) and M13 (4.1s) with a range of 250 Hz versus 60 Hz.

An overview of the full tone system from the results of normalizing 20 speakers, comparing males and females, and comparing smooth and checked tones

To provide a convenient overview, Figure 4.2 shows the trajectories of f 0 dEGG and O q dEGG averaged for each gender (10 males and 10 females), and for all 20 speakers. In addition, for a complete view of the tone system, Figure 4.3 provides a side-by-side plot for two sub-systems of five smooth tones (on the left) and two checked tones (on the right). The plot for smooth tones is actually the same as the one for 20 speakers in Figure 4.2c. Keeping in mind that averaged curves only offer a rough approximation of the data, Figures 4.2 and 4.3 allow for a recapitulation of some salient characteristics of Kim Thuong Muong tones.

From these normalized results,3 some general observations about the tone system can be proposed -with apologies for the large amount of overlap with observations made above when discussing patterns of similarity across speakers.

Smooth tones

Let us first consider the main sub-system of smooth tones.

Tone 1 is the longest of the five tones, although the difference is only less than 0.05 seconds, thus it makes no real distinction in terms of duration characteristics. This tone is remarkably level. It has a moderate final dip, also found in other tones, corresponding to the offset of voicing. It is a little below the speaker's average f 0 dEGG .

In opposition to Tone 1, Tone 5 is another flat tone but in a higher pitch level. In fact, it is the highest tone, with f 0 dEGG values always at the top of the speaker's range, so it can be called a 'top-high' tone.

Tone 2 and Tone 3 are characterized by falling and rising curves, respectively; the amplitude of the rise of Tone 3 is not quite as great as that of the fall of Tone 2. If taking two level tones (i.e., Tone 1 and Tone 5) as two measures, it can be noticed on all the f 0 dEGG graphs (on the left) of Figure 4.2 that while the rising tone (Tone 3) has a lower onset than the mid-level tone (Tone 1) and also a lower offset than the top-level tone (Tone 5), the falling tone (Tone 2) has a higher onset than the top-level tone and a distinctively lower offset than the mid-level tone. This phonetic asymmetry is to be expected if one takes into account a measure of declination in the course of affirmative utterances (statements). The most remarkable feature of Tone 4 is glottalization. The results from twenty speakers allow for correcting my earlier statement that glottalization "does not appear at the beginning but in the mid-part of the rhyme". On the 10-point normalized averaged tracings, the variability in f 0 dEGG increases noticeably as early as the third data point, and is unmistakeable at the fourth data point, as is the rapid dip in f 0 dEGG , both providing evidence of glottalization.

The open quotient patterns show a strong overlap across tones, with two salient characteristics. First, the curves share a similar overall shape: rather flat, but slightly modulated at both ends (the onset and offset), with Tone 4 an extreme case -a smooth V-shaped pattern. Secondly, there is a shared tendency for standard deviation to increase from beginning to end of the syllable rhyme.

The largest departure from these overall trends is the O q dEGG tracing of the women's average Tone 5, as it is less stable than the others, and clearly drops to a low position that is even lower than the offset of Tone 4. Since the values of f 0 dEGG of Tone 5

do not reveal anything out of the ordinary (it is always the highest tone, until the end), it can be hypothesized that this tone in females tends to be increasingly tense towards the end. Note, however, that the decrease in O q dEGG in the second half of the rhyme is clearly milder than the medial dip in O q dEGG for Tone 4, and that standard deviation is very high, so that the more pressed phonation type associated with Tone 5 in female speakers is nowhere as consistent, as a phonation type, as the creaky voice found in the medial part of Tone 4.

Although the difference in trajectory of O q dEGG between the tones is very small, it is still possible to notice a pattern: the highest tone (Tone 5) has highest O q dEGG , and the lowest tone (Tone 4) has lowest O q dEGG . This generalization must not hide from view the considerable asymmetry between the two, however. O q dEGG for Tone 5 is barely higher than for the other nonglottalized tones (Tone 1, Tone 2 and Tone 3)

-not to mention its gradual decrease in female speakers, leading it down to values lower than for Tone 1, Tone 2 and Tone 3-, whereas Tone 4 is way below all the others, with a consistent shape reaching lowest values from fourth to eighth data points out of ten.

The question of the correlation between f 0 dEGG and O q dEGG springs to mind again when noting that the O q dEGG curve of Tone 4 seems to follow its f 0 dEGG curve (as a V-shape), but the other tones do not have this neat correlation. Whatever the tone's shape, flat or rising or falling, their O q dEGG tracings are pretty flat and overlap with one another. To find clearer clues on this question, Figure D.3 in Appendix D directly displays the correlation between f 0 dEGG and O q dEGG . It confirms that there is generally no clear correlation between these two parameters for twenty speakers, with a large dispersion and no perfect positive or negative line. However, there does appear to be some correlation in the case of Tone 4 in not all speakers but several speakers such as: F3 (D.3a), F12 (D.3e), F17 (D.3g), F20 (D.3i), F21 (D.3j), particularly clear in the cases of F10 (D.3d), M1 (D.3k) and M11 (D.3q). The red dots in these cases form some sort of positive trend while the others show no trend and overlap. One possible explanation for this distribution is that it reflects the transition of different mechanisms. Tone 4

is the only tone that shows a rapid transition from a modal voice at the beginning to a creaky voice and back to the modal voice at the end. In cases where speakers have made this transition clearly in Tone 4, we can see a good correlation between f 0 dEGG and O q dEGG . Otherwise, in the case of speakers F13 (D.3f), M5 (D.3l), M8 (D.3n), M12 (D.3r), the red dots are still in the bottom position of the but no clear correlation. The other tones remain in modal voice, so there is no trend in their f 0 dEGG and O q dEGG distribution neither.

Overall, the plots are remarkably consistent between women and men, so that it does not come as a surprise that the figure showing normalized results across all 20 speakers also has a very similar outlook. The offset of voicing in women is clearer, though, with the last point of four modal tones falling more steeply. The duration differs by only 0.02 seconds, in a mild tendency for females to produce slightly longer syllable rhymes than males in this data set.

Checked tones

As noted above, duration by itself does not appear to play an important role in contrasts among the five tones of smooth syllables. On the other hand, duration differs greatly between smooth and stopped syllables. The tones in stopped syllables are only about half as long as tones in smooth syllables; this can be ascribed to the influence of obstruent codas. Final /p/, /t/, /c/ and /k/ are phonologically unspecified for voicing (there are no voicing opposition among final consonants in Kim Thuong Muong), but these codas are phonetically unvoiced, and appear to exert the full shortening effect that is cross-linguistically associated with final voiceless stops. Among stopped tones, there appears to be a relatively neat parallel between a mid-level-checked tone (Tone 6) and a high-level-checked tone (Tone 7). This is consistent with the well-established symmetry of the tonal system. Visually, looking at the f 0 dEGG tracings in Figure 4.3, Tone 6 and Tone 7 look like shorter versions of two smooth level tones, Tone 5

and Tone 1, respectively, since the pitch heights and the shapes of the contours look strikingly alike. Perceptually, according to my Vietnamese ears, these two tones are somewhat similar to the two checked tones D1 and D2 in Vietnamese, which are a rising-checked tone and a low-checked tone.

Considering the parameter of O q dEGG , unlike the tones of the smooth sub-system, the O q dEGG curves of Tone 6 and Tone 7 are clearly apart, and follow the distinction in f 0 dEGG , i.e. the higher tone (Tone 6) has higher O q dEGG -which is also higher than the O q dEGG values of all modal tones in the smooth system. The lower tone (Tone 7) has lower O q dEGG -which is lower than the O q dEGG values of all the tones in the smooth subsystem except Tone 4. The three points at the end show a sudden drop that breaks the previous upward trend. This decline also differs from the general pattern of an offset rise suggestive of syllable-final decrease in degree of vocal fold adduction in all the other tones. This would suggest that Tone 7 has a relatively tense offset, although this point needs to be verified with more data as here we only have 3 minimal pairs of checked tones (performed twice).

Glottalization as a component of lexical tone: A closer look at the glottalized tone across 20 speakers

To take a closer look at the glottalized tone, we will combine here observations about the entire tone system (Figure 4.1) and about Tone 4 in Figure 4.4 which shows raw data (i.e., one curve for each item) of f 0 dEGG and O q dEGG tracings for only this tone.

In this figure, the color of the lines changes gradually from red to blue to reflect the order of items in the experiment. Red curves are used for items at the beginning of set, maroon curves at the middle of set, and blue curves at the end of set. This color code is also applied for all figures which show one curve for each item. The aim is (i) to make the lines easier to tell apart from one another and (ii) to provide a way to visualize possible changes in the speakers's behavior in the course of the recording (commonly observed changes include gradually decreasing f 0 : see [START_REF] Niebuhr | Speech data acquisition: the underestimated challenge[END_REF]. The same range of f 0 and O q is used in all the figures (men and women) to facilitate comparison.

A general look at twenty speakers

As already mentioned in several places in this thesis, it has been well noticed that Tone 4 is the most striking tone of the system with both f 0 dEGG and O q dEGG parameters well-distinguished from all the other tones.

The ideal cases of Tone 4

Tone 4 determines the bottom base of the speaker's range since this is the lowest tone in the system. In data from most of the twenty speakers, it is easy to separate the red line from the rest of the system. This tone usually has half of the f 0 dEGG range to itself. It alone occupies a separate space in the lower part: the highest points at two ends (in positions of onset and offset) of this tone are lower than all the other tones, and the curve plunges to bottom values in the middle part. Tone 4 is the only tone that has a complex trajectory combining descending and ascending components, while the other tones have only a straight trajectory (either flat, rising or falling). f 0 dEGG curves of Tone 4 stand out by a clear dip in the middle, which is more V-shaped than U-shaped. The speakers who possess this well-distinguished shape of Tone 4 are F3 (4.1a), F7 (4.1b), F9 (4.1c), F19 (4.1h), F20 (4.1i), M9 (4.1o), and M11 (4.1q). These are the speakers that have the lowest f 0 dEGG values of Tone 4, which can reach down to about 50 Hz. Those f 0 dEGG trajectories go down from the low-mid part of the speaker's range to the bottom of range, at least 15 to 20 semitones lower. The O q dEGG curves of these speakers likewise tell the same story. It is possible to draw a line to set apart Tone 4 (in red) from the rest of the system. In the upper part, the O q dEGG curves of four tones overlap, and they are consistently around the mean of 50%, and the bottom part of the standard deviation usually around 40%.

Whereas, in the lower part, there is only Tone 4: the O q dEGG curve of this tone plummets from initial mid-range values (which are already lower than all the other tones) to the very bottom of range. In some speakers (most saliently for speakers F7 (4.1b) and F20 (4.1i)), most of the O q dEGG values of Tone 4 were excluded, due to the issue of unclear opening peaks. The values retained for 20 speakers in general reflect the consistent presence of very low values of O q dEGG , especially in the middle of the rhyme, which are commonly below 30%, and can even reach strikingly low values, on the order of 15%: for speakers F3 (4.1a), F7 (4.1b), F17 (4.1g) and M11 (4.1q)). These values constitute compelling evidence of the presence of creaky voice.

The cases of less distinct Tone 4

Apart from these ideal contrasts for Tone 4, we have other cases which are less distinct, and accordingly, with a narrower range of f 0 dEGG . Considering the parameters f 0 dEGG and O q dEGG tracings in Figure 4.1, we can propose a rough classification into three sets of cases:

• The case of speaker F10 (4.1d), F12 (4.1e) and M10 (4.1p): the distinction of the f 0 dEGG curve of Tone 4 from the rest is less striking but the O q dEGG curve still maintains a neat distance from the others. In particular, in the case of M10 (4.1p), the f 0 dEGG curve of Tone 4 is not strikingly apart from that of the other tones, but its O q dEGG curve is still well isolated. • The cases of speakers M7 (4.1m), M8 (4.1n), M10 (4.1p) and F21 (4.1j): the f 0 dEGG curve of Tone 4 is kept a little separate from the other tones, with its V-shape less marked. The O q dEGG tracing is still at the bottom of the system but just next to the other tones. A borderline case for this category is speaker M13 (4.1s) with a minimal distinction in f 0 dEGG and no salient distinction in O q dEGG . • A special case is F13 (4.1f) with clear f 0 dEGG tracings for all the tones, which even make it seem like she is overdoing the contrasts: exaggerating them towards an ideal model, with a nice rise of Tone 3 and a clear V-shape of Tone 4.

However, the O q dEGG parameter does not bring out a massive distinction between the glottalized tone and the rest, although Tone 4 still has the lowest O q dEGG values. Similar to this case, M14 (4.1t) also presents a nice tone system according to f 0 dEGG , but the O q dEGG values are not distinct: all the curves of five tones overlap. The tonal space is used with much more abandonment by speaker F9 (4.1c), whose long rhymes and high f 0 dEGG set upper bounds for the entire data set. Variability in her data is somewhat higher, too (reflected in wider standard deviation ranges), suggesting that the speaker avails herself of the comfortable distance that she leaves in-between tones to allow herself somewhat more freedom in the exact pitch at which she sets individual tokens of the tones that she produces. Tone 4 shows ample phonetic evidence of creakiness, starting as early as the first quarter of the rhyme. Conversely, speakers with the smallest tonal spaces and with no striking visual evidence of using glottalization for Tone 4 have very small standard deviation across tokens of the same tones. Speaker M13 is clearly an epitome of a super-economical (Malthusian?) approach to tonal contrasts, making up (to an extent that remains to be verified perceptually) for the small amplitude of the difference across tones through remarkable consistency across tokens. Chance has it that M12 and M13 received adjacent numbers when speakers were assigned numbers, resulting in the juxtaposition, as Figures 4.1r and 4.1s, of two tonal spaces of remarkably different proportions. Once the initial shock wears off, a phonologist's eye can nonetheless acknowledge strong structural similarities: Tone 3 is rising, whether dramatically or in the most subdued way, and so on.

Looking at the O q dEGG tracings alone, there is a majority of speakers in whose data Interestingly, this leaves about one third of speakers for whom the picture is not so obvious. It should however be remembered here that the estimation of the glottal open quotient from electroglottography can be difficult to carry out for some types of signals.

If the O q dEGG curve for speaker M13's Tone 4 is not as clearly set apart from that of the other tones at the point where the f 0 dEGG curve shows clear hints of irregularity in vocal fold vibration, it is not unlikely to be due to the absence of some data points in the matrix of O q dEGG results for this tone. This difference is more salient for speaker F3 (4.1a), since the O q dEGG values for F13 (4.1f) are overall lower and thus less distant between Tone 4 and the rest. But the shape of the O q dEGG curves for speaker F13 contributes to keeping Tone 4 apart from the others, since its O q dEGG curve only begins to rise after a steady decrease that lasts until the middle of the averaged curve, whereas an overall increase in O q dEGG is found for all the other tones starting no later than one-third into the rhyme.

The above remarks allow for several generalizations. Some of these generalizations are negative: thus, a large amount of creakiness does not necessarily go hand in hand with a boisterous realization of all the tones. Speaker F12 (4.1e) has outstanding amounts of creakiness in Tone 4 but an otherwise very moderate spacing of tones.

Other generalizations are positive, in the sense that they bring out trends. Thus, even though the phasing of glottalization is highly different across speakers, patterns do emerge. To categorize into four rough categories depending on whether creak occurs early, medially, late, or not noticeably (in the curves in Figure 4.1), it appears that there are more late creakers (eight: {F7 (4.1b), F9 (4.1c), F10 (4.1d), F12 (4.1e), F13 (4.1f), F20 (4.1i), F21 (4.1j), M11 (4.1a)} and medial creakers (seven: {F3 (4.1a), F17 (4.1g), M1 (4.1k), M5 (4.1l), M9 (4.1o), M10 (4.1p), M14 (4.1t) } than early creakers (only M8 (4.1n) and M12 (4.1r)) and (apparent) noncreakers (only F19 (4.1h), M7 (4.1m) and M13 (4.1s)).

A comparative look at gender differences

The shape of Tone 4 is less V-shaped for men, which does not tell us that men creak less than women, but that they creak in a different way from women. Figure 4.4 reveals that women tend to perform Tone 4 with a tremendous turbulence of f 0 dEGG , while these curves in men are more stable and follow the V-shape as the averaged results.

Eight women out of ten have jittery f 0 dEGG curves, with a large fluctuation generally with an amplitude from 30-50 Hz up to 250-350 Hz. In the case of speaker F19 (4.4h), jittery curves of f 0 dEGG only appear in a few items during the middle part of the experiment, as evidenced by the maroon-colored values at 200 Hz. Speaker F21 (4.4j) is the only one that does not have any item with jittery f 0 dEGG . This does not mean that women only do glottalization with jittery f 0 dEGG . In the cases of speakers F13, F17 and F20, it is easy to spot that there are clearly V-shaped curves that make the middle part (in F13) and the bottom part (in F17 and F20) more consistent and dense. This is much less obvious in the other speakers but from my logs during data processing, I can confirm that women mix different ways of creaking/glottalizing but apparently prefer to creak irregularly.

In an opposite situation, there is one man out of ten whose Tone 4 This difference in glottalized characteristics between male and female speakers is reflected well in the distribution of f 0 dEGG in Figure D.2 in Appendix D. In general, the interquartile range of the female data is much broader than that of the male, especially in the case of speakers F30, F9, F12 and F20 with a spread of at least 70 Hz. The two speakers with negligible and no jitter in the f 0 dEGG curves, namely F19 and F21, have the narrowest interquartile range.

In the male data, the distribution of f 0 dEGG does not really reflect what we can observe in the raw data in Figure 4.4 since the only male speaker M5 reported having jittery f 0 dEGG as in females but his interquartile range is not the widest one, but rather M11. This is the speaker whose Tone 4 I could say is the most creaky, both perceptually and signal-visually: the V-shape of Tone 4 is the most plunging of the In fact, with this kind of signal, we can technically treat the micro-peak as part of a cycle since it is not a complete cycle. The method of re-setting the threshold to integrate the micro-cycles within a larger cycle will not work since their amplitude is almost equal to that of the normal cycles, as can be seen in the dEGG signal in Figure 4.5b. It is possible to use the more manual method to combine the microcycle with its adjacent cycle, so we will have a smooth f 0 dEGG curve without those unreasonable values. However, when processing the signal, I decided to keep the result that PeaKDet automatically detected, to keep in mind this fascinating phenomenon.

There is a particular gesture that occurred during the glottaliztion of Tone 4 in this speaker; it is perhaps no coincidence that he is the oldest participant (he was born in 1937).

Regarding the O q dEGG parameter, as can be seen in the graphs on the right of Figure 4.4, more O q dEGG values had to be discarded in the cases where there is jitter, with a sparser density of values. Notably, in the case of speaker F20, only two elements retained their O q dEGG curves, namely is the last target syllable of the list in Table 3.1, over syllable ku⁴.

In addition, very high O q dEGG values, above 60%, are recorded much more often in cases of jittery f 0 dEGG , which is actually easy to explain due to the smaller cycles. It seems unreasonable to have such high O q dEGG values in a glottalized portion, and especially in creaky voice, since this phonation type is at the bottom of the speaker's voice range, below the modal register. On the other hand, I find that if we suppress all the precise opening peaks of the small cycles, it will create an artefact. There seemed to be no point removing high O q dEGG values: instead, they are part of the results obtained by the method employed here, which follows vocal fold vibration very closely, and treats successive positive peaks as evidence of distinct glottal pulses, as a (debatable) matter of convention.

According to the characterization and sub-classification of creakiness in Section 5.2, we know that the jittery f 0 dEGG curves here mean that women tend to perform multiplypulsed creak with double complex-repetitive patterns, or aperiodic creak which complete irregularity in successive pulses. Men, on the other hand, generally have single pulsed creak or usually pressed voice.

Chapter 5 Discussion

This chapter builds on the "ground-level" information provided in the previous one (Results) to propose various higher-level elaborations about the tonal contrasts found in Kim Thuong Muong. The reflections first hinge on the outlook of the tone system (in section 5.1). A second part of the chapter is devoted to glottalization as seen in the perspective of general phonetics: exploring in what sense, and to what extent, the facts observed in Muong can make a contribution to a fine-grained understanding of the linguistic roles of glottalization and creaky voice. From there, we progress towards the broader picture of Muong prosody: the interplay between tone and intonation ( §5.5). As a final flourish, observations about a potential intonational tone in Muong are set out ( §5.5.4): a prosodic pattern on two sentence-final particles (the one interrogative, the other affirmative) that illustrates the space for linguistic creativity opened up by the presence of glottalization in the tone systems of languages in contact (in this instance, Muong and Northern Vietnamese).

General outlook of the Kim Thuong Muong tone system

A first thing to say about the Kim Thuong Muong tone system is that its general outlook is here confirmed to be as described in my earlier work (M.-C. [START_REF] Nguyên | The tone system of Kim Thượng Mường: an experimental study of fundamental frequency, duration, and phonation types[END_REF]. It has five tones, plus two: its tones are divided into two sub-systems, five contrasting tones on smooth syllables and two tones on checked syllables. No additional tones were turned up in the course of fieldwork since 2016 (although interesting phenomena at the border line between tone and intonation did come up, as will be elaborated on in §5.5). For the sake of simplicity, the tones are labeled with numbers from one to five for the smooth system, and six and seven for the checked system. There is no specific logic to this numerical labeling, which simply followed an order of discovery in early fieldwork. Readers can refer back to Table 2.6, which recapitulates each tone's phonetic-phonological characteristics and provides shorthand names and corresponding labels using the five-level system taken up in the International Phonetic Alphabet [START_REF] Chao | A system of tone letters[END_REF].

As to the phonetic/phonological properties of each of the tones, there is, again, an overall good match between the generalizations proposed back in 2016 and the fresh observations on the tone system reported here, based on systematic implementation of the most basic procedure to study a tone system experimentally -recording minimal sets. The results from twenty speakers confirm the organization of Kim Thuong Muong tones into what I find to be an elegant, neat and symmetrical space (as shown in Figures 4.1,4.2 and 4.3 of the previous chapter). The system makes use of combinations among several phonetic dimensions to contrast between the tones: levels, contours, plus creaky voice.

Firstly, pitch levels suffice for the distinction of two level tones: Tone 1 and Tone 5. Tone 1 is phonetically flat and typically located around the middle of the speaker's range, usually a little lower than the speaker's average, as can be confirmed by comparing the results in Figure 4.1 and the average values provided in Table 4.1. On the basis of this characteristic, I shall refer to this tone as a low-mid level tone.

Tone 5, in direct contrast to Tone 1, is another flat tone but at a higher pitch level. This is actually the highest tone in the system, with the f 0 dEGG values held at the top of the speaker's range throughout its duration.

These two tones are generally well maintained in a moderate and effective pitch distinction, without the support of other phonetic parameters to enhance the f 0 contrast or supplement it. Although, as can be seen in Figure D.1, most speakers have these two tones with only five semitones of difference, I have never had difficulty recognizing them. (On this and other points, readers can form an opinion for themselves by listening to the data set, which is available from the Pangloss Collection.1 )

The second factor used to contrast the tones is modulation of pitch. Besides the two level tones that have distinct pitch levels, the other three tones each has a unique pitch contour.

Tone 2 is a falling tone. It has a high beginning and descends to a low ending, as low as Tone 1, but not as low as Tone 4 (i.e., the glottalized tone). This tone normally starts at the same onset as the top-high level tone (Tone 5) and ends near the offset of the low-mid level tone (Tone 1), with a shape similar to a children's slide: a mild slope at both ends and a steeper drop in the middle.

Tone 3 goes in an opposite direction. It is characterized by a rising curve, although the extent of the rise in this tone is usually not as great as that of the fall in Tone 2. This is not surprising from a typological perspective, as a rise in f 0 is perceptually more salient than a fall (all other things being equal).

Contrasted with all the others, Tone 4 is the only tone to possess a complex contour: falling-rising with the onset and offset located at almost the same pitch level, below the low-mid lever tone (Tone 1). As mentioned earlier, most speakers have an f 0 dEGG curve for Tone 4 that stands out by a clear dip in the middle, which is more U-shaped than V-shaped.

A further phonetic parameter, which sets Tone 4 apart from all the others, is the contrast of phonation types between the modal voice and the creaky voice. It can be observed in the graphs of O q dEGG values (on the right of Figures 4.1 and 4.2), which provide insights into the degree of vocal fold adduction, that Tone 4 is the only tone clearly distinguished from the others. In most cases, it would not be difficult to draw a line to separate Tone 4 (red line) from all the rest of the system. The O q dEGG curves of the four tones in the upper part overlap, and they are systematically located around a mean value of 50%, and the bottom part of the standard deviation is generally around 40%, i.e. these tones are squarely in the range of modal voice. By contrast, in the lower part, only Tone 4 is present: the O q dEGG curve of this tone plummets from initial mid-range values (which are already lower than those of all the other tones) to the very bottom of the range. Most of the O q dEGG values from Tone 4 had to be excluded at the stage of data verification, reflecting the issue of unclear opening peaks on the derivative of the electroglottographic signal. The values retained are thus to be taken carefully. It is nonetheless safe to conclude, in view of the data from the twenty speakers, that there is a consistent presence of very low values of O q dEGG , especially midway through the rhyme, where the values are commonly below 30%. These values are strong evidence for the presence of creaky voice.

In Kim Thuong Muong, canonical realizations of the glottalized tone (Tone 4) show a lapse into creaky voice rather than a glottal stop or glottal constriction. Investigations into different kinds of materials (such as narratives, or elicited materials in which the syllables carrying Tone 4 are not under focus) are likely to uncover a wider range of realizations, however. Since Tone 4 is the only glottalized tone in the Kim Thuong Muong system, its glottalization can be expected to show a larger field of allophonic variation than in tone systems that contrast two or more glottalized tones (such as Hanoi Vietnamese, for instance). It stands out nonetheless as an important observation about Tone 4 that its nonmodal phonation type is consistently creaky. A phonological interpretation is that this tone is specifically a creaky one: not simply a phonologically glottalized tone (in a general sense) that happens to have much creak for some sort of low-level phonetic reason.

It may come as a surprise that no mention was made so far of duration, often an important (potentially distinctive) characteristic in tone systems of East and Southeast Asia. It must be stated that duration does not play any detectable role in the contrasts between the five tones of the smooth syllables. Although there are some measurable average differences, such as that the two tones with a higher offset (Tone 5 and Tone 3) are generally shorter than the two tones with a lower offset (Tone 1 and Tone 2), and Tone 1 is always the longest tone in the system, these differences are negligible: they are only a few milliseconds long.

On the other hand, the duration is markedly different between smooth and checked syllable rhymes. As can be seen in Figure 4.3, the checked tones are roughly half as long as the smooth tones. This bears a clear relationship to obstruent codas. The final consonants /p/, /t/, /c/, and /k/ are phonologically unspecified for voicing (there is no voicing opposition among the final consonants in Kim Thuong Muong), but these codas are phonetically unvoiced, and appear to exert the full shortening effect that is cross-linguistically associated with final voiceless stops.

Within the checked sub-system, Tone 6 and Tone 7 are both phonetically short and flat. There appears to be a relatively clear-cut parallel course between a mid-level tone (Tone 6) and a high-level tone (Tone 7).

Concerning the checked sub-system, there are two points that I would like to discuss here. First, by comparing the current result of the checked sub-system (Figure 4.3) with the one I reported in the 2016 study (M.-C. Nguyên, 2016, pp. 66-67), one can easily notice that the results are vastly different. The two checked tones in this latest study are both phonetically flat, whereas those in the previous study were clearly descending (Tone 6) and ascending (Tone 7), respectively. This difference is caused by the different materials of the phonetic experiments. In this study, we used only minimal pairs of real words, which ensures that the result here is proper. It was a shortcoming of the 2016 experiment that I did not have material on real minimal pairs of checked syllables, but only relied on nonsense words combined from some phonemes that exist in Kim Thuong Muong, as explained in (M.-C. Nguyên, 2016, pp. 22-26) -clearly not a reliable method, as it turned out. The method of using nonsense words in phonetic and phonological experiments is actually quite common (Michael S Vitevitch et al., 1997a;Michaud, 2004b;Hay, Drager, and Thomas, 2013b). However, this method turned out to be inappropriate in an unwritten language like Muong.

First of all, it is an issue how to show the phonemic combinations for nonsense words in an unwritten language. There is no other way but to borrow another writing system that all native speakers know and use fluently, in this case Vietnamese. This leads to an obvious drawback: the consultant's experience in reading and writing is intimately tied to their practice of the Vietnamese language. All of the consultants had received training in Vietnamese writing throughout their elementary school years, whereas none had received training in Muong writing in school or later.

I thought it was possible to adapt the writing system of Vietnamese to the Muong, and, through a thorough training phase, to instruct consultants to respond to stimuli using Muong tones and not Vietnamese tones. But this was definitely a failure. The Muong language does not have an established writing system to encode the language systematically, and their native speakers use the language as an oral one and are mostly unaware of the specifics of their phonemic system. In this context, "classroom" behavior is likely to occur at various points: code-switching between the sound systems of Muong and Vietnamese, and perhaps mixing the two in varying proportions.

The task becomes even more impossible when even the researcher does not firmly grasp the difference between the two languages. With my nascent experience in the early stages of studying this dialect, I struggled to get rid of the inherent Vietnamese tonal system in order to learn Muong, which bears a clear overall family resemblance but is truly different in detail. Using the Vietnamese tone background ("this tone of Muong sounds like that Vietnamese tone") caused me to lose a lot of time in the process of acquiring and perceiving another tone system -but at least it allowed me to clarify forever that those are truly two independent tone systems. The nonsense word experiment was conducted during that stage of my learning, and so I was not self-assured enough in my mastery of Muong tones to monitor code-switching problems as they were occurring.

However, even if the researcher is well versed in both languages, it is still not a reliable guarantee that such an incident will not occur when the phonemes of the two languages are closely similar. My failure demonstrated that nonsense word experiments are unlikely to be possible in an unwritten language, and in any case, that they involve clear risks of code-switching between two languages.

The second point I would like to discuss here is the question of the relationship between two sub-systems in tonal languages, i.e., between smooth tones and checked tones.

In Vietnamese, the most closely related language to Muong, there have been opinions that the two checked tones (etymologically: the D-tones) could be allophones of two B-tones, due to their similar perception. Dating back to the 17 th century up to now, the orthography used the same diacritics and also the same names: "thanh sắc" for B1 and D1, and "thanh nặng" for B2 and D2. However, the orthographic convention whereby they are written in the same way may initially have been a matter of convenience: the authors of the romanized Vietnamese alphabet had to use a wide set of diacritics for tones, and using seven tone diacritics rather than five would have been uneconomical, since (to use terminology that is anachronistic with reference to 17 th century language work) there is a different distribution for the stopped tones and the smooth tones, which do not occur on the same rhymes. The stopped and smooth tones of Vietnamese are now generally recognized to be phonetically distinct (Kirby 2011, pace Earle 1975).

For Muong, the issue is whether the two checked (stopped) tones, Tone 6 and Tone 7, are allophones of some smooth tones: for instance, of Tone 5 and Tone 1, which are somewhat similar phonetically. Looking at the f 0 dEGG tracings in Figure 4.3, Tone 6 and Tone 7 visually look like a shorter version of two smooth level tones, Tone 5 and Tone 1, respectively: the pitch heights and the shape of the contours look very much alike.

However, from a structural point of view, it is clearly better to avoid use of the notion of allophony here, and consider the checked tones as a standalone system. Kim Thuong Muong's tone system has 5+2 tones, with two sub-types of five smooth tones and two checked tones.

All in all, the tonal system (as viewed through f 0 dEGG tracings) thus appears relatively symmetrical, consisting of two parts. In the upper part, there are a low-mid level tone (Tone 1) contrasting with a top-high level tone (Tone 5), and a falling tone (Tone 2:

falling from the top to the low-mid of the speaker's range) contrasting with a rising tone (Tone 3: rising from low-mid to the top of the speaker's range). Meanwhile, in the lower part, the glottalized tone (Tone 4) looks symmetrical along the time scale, with offset values close to onset values, and glottalization (canonically, creaky voice) in-between. The checked sub-system also participate in this well-established synchronic pattern distinguishing higher and lower tones, with a clear and parallel contrast between a high-level-checked tone (Tone 6) and a mid-level-checked tone (Tone 7).

These observations hold for all twenty speakers, strongly suggesting that these are characteristics of the Kim Thuong Muong tone system, not idiosyncratic properties (specific to one or several speakers). In addition, since these characteristic are not effect of phonemic composition such as vowel quantity, vowel height, stop or fricative character of the initial consonant, or the like, this confirms that they are properties of lexical tones, not other phonemic components.

This result is consistent with the suggestion that Kim Thuong Muong's tones are not realized by pitch alone, but by a complex combination of characteristics: most saliently the combination of pitch and nonmodal phonation types commonly found among Vietic languages. It reinforces the observation that all Vietnamese languages have at least one glottalized tone. Besides the well-known case of Vietnamese, we also have some studies on other languages and dialects, such as Arem [START_REF] Ferlus | Arem, a Vietic language[END_REF]), Ruc (Tấn Thành Tạ, 2021). The next step is to make comparisons of these languages to bring out the general pictures of glottalization, how they are similar or different in terms of characteristics and function, and to what extent their variations and their role in the tonal system. In this study, we will be able to make some comparison between Kim Thuong Muong and Vietnamese because the similar method and result of Vietnamese in (Michaud, 2004b;Brunelle, 2009b;Brunelle, D. D. Nguyên, and K. H. Nguyên, 2010;Kirby, 2011) that allows for a reasonable comparison here. Comparisons with other Vietic languages and dialects are worth continuing later.

A characterization and classification of sub-types of creaky voice based on audio and electroglottographic signals

Building on the framework of glottalization concepts and nomenclatures summarized in the previous section, I attempt here to suggest a sub-classification of creaky voice into subtypes attested among realizations of the glottalized tone (Tone 4) in Muong, illustrating each sub-type by an example. By sifting through the data obtained, it is not difficult to notice that creaky voice in Tone 4 is realized with much variation -which can be described as allotonic variation, since creak is part of the tone's phonological specification. An obvious thing to do at this point is to clarify the nomenclature. A four-way classification will be proposed as a basis for further analysis. But before presenting and exemplifying these four types, two clarifications are in order here. Firstly, since there is so far no consensus in the phonetic classification of creaky voice into sub-types, the name chosen here for each of the four proposed sub-types is essentially based on its salient phonetic characteristics: single-pulsed creak, multiplypulsed creak, aperiodic creak, and pressed voice. This choice appeared better than borrowing from the list of commonly-used labels from existing nomenclatures (as discussed in §2.3.1).

A second clarification is that the representative examples chosen here for each type are admittedly cherry-picked: they constitute extreme cases -almost ideal, even though they are fully real examples from the experimental dataset collected for the present study. These examples are selected to bring out with greatest clarity the properties that characterize the categories as classified here. There are frequently less clear-cut cases, cases on the borderline between certain categories, and complex combinations of two or more categories. Those are definitely worthy of more attention than could be granted to them within the time frame of the present study. Addressing these cases in full detail is a task that has to be deferred until future work; it is hoped that the present discussion can serve as a useful stepping-stone in that direction and there can be cumulative progress.

Type 1: Single-pulsed creak

Going from simple to complex, the first sub-type that we identify and classify as a sub-category of creakiness is single-pulsed creak, exemplified in Figure 5.1. Three key properties of this sub-type are: (i) glottal cycles (periods) are long, and remain a train of single, discrete pulses, as in modal voice, and as opposed to the double-pulsed or multiple-pulsed patterns which will be described below; (ii) both f 0 dEGG and O q dEGG reach low values (the lowest in comparison to the three other types of creak, andconspicuously -also very low as compared with modal voice); and (iii) quasi-periodicity in a strict technical sense might become lost when the pulses get longest (i.e. there can be visually salient differences in the durations of successive glottal cycles) but these variations do not go so far as to interrupt voicing. This is an important difference from the perception of a telltale interruption of voicing in a glottal stop.

This sub-type is associated with different labels according to different classifications, such as creak or vocal fry in Hedelin and Huber (1990) (a classification which distinguishes creak from creaky voice), damping or creak in [START_REF] Batliner | MÜSLI: A Classification Scheme For Laryngealizations[END_REF], creak in [START_REF] Redi | Variation in the realization of glottalization in normal speakers[END_REF], and prototypical creaky voice or vocal fry in [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF].

Two examples of single-pulsed creak are provided in Figures 5.1 and 5.1 in order to show how wide the range of variation of this sub-type can be. Both examples are taken from exactly the same dataset of speaker M11, in the same first minimal set. They are from the syllable /paj⁴/. The only difference is that they are in two different contexts. The first example (in Figure 5.1) is spoken in isolation. This is the most extreme case of this type of creak that was encountered to date. It is clearly apparent from the signals and the extracted parameters that creakiness occurs right from the beginning of the rhyme. The pulses are stretched to a maximum duration in the 9th to 11th cycles. Quasi-periodicity is lost, as there is uneven duration across successive cycles, but visually and auditorily, there is no real interruption of voicing. The bottom pane shows the f 0 dEGG and O q dEGG calculated automatically with PeaKDet (which, as explained in the Method chapter, operates cycle by cycle, not through autocorrelation). It can be seen that five or six cycles of jittery f 0 dEGG are followed by rock-bottom values (below 40 Hz and even down to 20 Hz): extremely low-frequency voicing.

Fundamental frequency and open quotient rise again after reaching the lowest values, but remain low (lower than they are early on in the rhyme). The opening peaks on the derivative of the electroglottographic signal are still (just barely) clear enough to allow for confident evaluation of the glottal open quotient. It is not unreasonable, in view of the shape of the electroglottographic signal, to consider that these cycles have an extremely short open phase, and that the lowest O q dEGG values (those in orange, correcting for two outliers at the 9th and 15th cycles) provide good estimates: O q dEGG is on the order of just 5% (i.e. rock-bottom values, like for f 0 dEGG ) for the longest cycles. This case undeniably has to be considered as creak (phonation mechanism zero in terms of the classification of [START_REF] Roubeau | Laryngeal vibratory mechanisms: the notion of vocal register revisited[END_REF]). Overall, this example can be described as an extreme sample of clear lapse into creaky voice, with the lowest possible f 0 dEGG and O q dEGG , but still with a single pulse per cycle. A possible physiological interpretation is that phonation is almost arrested by the strong glottal constriction, and only continues 'pulse by pulse' as puffs of air find their way through the closed sphincter.

The second example of single-pulsed creak (Figure 5.1), on the other hand, is from a token spoken in the carrier sentence. We recognize this as the commonest case of single-pulsed creak because, compared to the previous case, this one occurs much more frequently, and across speakers. In other words, whereas the previous example is only found particularly in the case of speaker M11 when the words are spoken in isolation, and can hence be seen as a case of hyper-articulation, the sample in Figure 5.1 is a representative of this sub-type of creak as it appears in most of the cases and for most speakers.

The token shown in Figure 5.1 does not show stunningly long, discrete pulses as in the previous example. Instead, the length of successive cycles increases with some regularity, before decreasing again. There are no sudden, dramatic changes. The cycles are gradually stretched out (here: during the first 8-9 cycles), in a gentle transition towards the very low f 0 dEGG values in the second half of the rhyme: a low range where f 0 dEGG values remain until the end of voicing. As a result, the values of both f 0 dEGG and O q dEGG do not reach the same extremes as in Figure 5.1b, but they are still very low. Fundamental frequency gets under 100 Hz, reaching down to 40 Hz towards the end (in the 13th cycle). The O q dEGG values are consistently below 40% and even drop to 20% in the second half, an indicator of the presence of strong glottalization. In consulting other works, this kind of signal seems closest to what is proposed as creak (vocal fry) in Hedelin and Huber (1990, p. 361) and as damping in Batliner et al. (1993, p. 7).

Despite the huge difference between the two samples examined above, we believe that they should not be considered as two distinct sub-types, but as two distant points along a continuum characterizing one and the same type, namely single-pulsed creak. The interpretation put forward here is that the actual phonetic realization will be closer to one end of the continuum or the other based on differences in prosodic environments. The more emphasis is placed on a (monosyllabic) word, the more care will be put into its articulation, and the more time will be spent on it (allowing for special cases such as phonologically -contrastively -short phonemes, of course, whose lengthening could jeopardize their proper identification, defeating the communicative purpose of emphasis). This intuition can be stated in terms of allocation of resources: when speakers focus on the syllable (including its tone) and hyper-articulate it, then the realization gets closer to the extreme side of the continuum, whereas when resources allocated to the tone are less abundant, then the realization is closer to the other end. Thus, the fewer constraints are placed on phonetic realization by a syllable's context (coarticulatory constraints and temporal constraints), the longer the single-pulsed creak, and the more discrete (far apart) the successive pulses.

On this basis, the detection of this kind of signal (single-pulsed creak) can be based on the rate of f 0 dEGG change (hereafter called delta f 0 rate). Comparing the rate of change (in absolute values) of the two samples examined above with the rate found in tones other than Tone 4 (tones devoid of phonological creak, and hence hypothesized to have non-creaky phonation: modal voice, for short) to set a threshold, a first-pass approximation is to set a threshold at 10%: this value works well for the two samples under consideration, as can be seen in Figure 5.6 (please mind the difference in y axis scales for the two sub-plots, (a) and (b)). This topic will be taken up further below, and the threshold adjusted accordingly, as we encounter further cases of single-pulsed creak.

Type 2: Multiply-pulsed creak

In the literature, the terminology for multiply-pulsed creak as a sub-category within creaky voice is relatively consistent, in keeping with the high degree of specificity of its characteristics. It is sometimes referred to as diplophonia or diplophonic phonation, as in the studies of [START_REF] Hedelin | Pitch period determination of aperiodic speech signals[END_REF], [START_REF] Batliner | MÜSLI: A Classification Scheme For Laryngealizations[END_REF], and [START_REF] Redi | Variation in the realization of glottalization in normal speakers[END_REF]. It is called multiply pulsed voice in the classification put forward by [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]. We employ the term "multiply-pulsed creak" because, in contrast to the previous sub-type, the telltale sign of the present sub-type is the quasi-regular double repetitive pattern with alternating short and long glottal periods.

This pattern is prominently reflected in the electroglottographic signal and its derivative (dEGG), with the length and height of the signal in the creak portion alternately varying from wide to narrow and also from high to low.

Triple-repetitive patterns, mentioned and illustrated in [START_REF] Blomgren | Acoustic, aerodynamic, physiologic, and perceptual properties of modal and vocal fry registers[END_REF]Blomgren et al. ( , p. 2655)), are not found in the dataset of the present study, which (so far as I am aware) only contains double-repetitive patterns. But since triple-repetitive patterns are attested from the point of view of general phonetics, it is clearly better to use the more general label "multiply pulsed creak", rather than "double-repetitive pattern" or "double-repetitive creak", even though the two coincide in the case of the data set at hand.

To take a close look at the example in Figure 5.1, a first, obvious observation is that there are three main parts in this example: non-creak, creak, then back to non-creak again. The double-repetitive pattern covers half of the syllable (specifically: from 34 th cycle to 71 st cycle). The complex-repetitive pattern is reflected in a saw-like shape in both f 0 dEGG and O q dEGG tracings.

A caveat is in order here, concerning the values of f 0 dEGG : these values, calculated cycle by cycle on the basis of peaks in the derivative of the electroglottographic signal (as explained in §3.3.2), must be taken with a grain of salt. Much lower values would be obtained if the complex-repetitive pattern as a whole were considered as the pattern that repeats itself in time, and hence as the basis for estimating periodicity (and hence fundamental frequency). Provisionally looking at the raw f 0 dEGG and O q dEGG values as estimated by the PeaKDet script nonetheless allows for bringing out patterns that help detect multiply-pulsed creak, keeping in mind that detection and phonetic/phonological analysis are two different things.

In term of f 0 dEGG curve, the onset and offset in this example are in the same register, in the vicinity of 200 Hz. The long complex-repetitive pattern in the middle has a range of oscillation between 100 and 220 Hz. The O q dEGG values of this token can be estimated with some precision. The glottal open quotient is in the range between 45% and 35% (i.e. clearly low values) in the initial and final portions (those that do not have multiply-pulsed voice). During the creaky portion, O q dEGG oscillates between markedly different values for the smaller pulses (on the order of 50%) and the larger ones (on the order of 25%: values clearly indicative of glottalization). This alternation in O q dEGG values, with the longer glottal cycles having lower O q dEGG than the shorter ones, offers an interesting insight into the strong differences between the main pulse (which, even taken by itself, clearly looks glottalized) and the secondary pulse (which, by itself, has neither of the two following indicators of glottalization: low f 0 dEGG and low O q dEGG ).

This sub-type of creak looks like one that will be easy to detect automatically, based on detection of the peaks in the dEGG signal corresponding to glottis-closure instants. Knowing the duration of each glottal pulse is enough to notice the alternation of short and long pulses, characteristic of double-(and triple-) repetitive patterns. The following paragraphs explain how this hypothesis was put to the test.

When conducting an automatic search, the two relevant variables are precision and recall rates. Precision is the proportion of correct identifications among the retrieved results. Recall is the proportion of relevant instances that were retrieved by the search. (To clarify with examples: if the search returns all and only the relevant results, precision and recall are both 100%; if the search returns results that are all correct but miss relevant instances, precision is 100% but recall is low; and if the search returns lots of results including all the relevant ones, precision is not so good but recall is at 100%.) In this instance, the aim is to get the multiply-pulsed-creak detector to detect from the 34 th to the 71 st cycle.

Although this sub-type is not difficult to detect visually by means of its specific quasi-regular pattern, it is impractical to detect it automatically in the present workflow. The most frequent and obvious limitation of automatic detection is that the larger patterns, containing one large peak and one or more smaller peaks, are not recognized as such by PeaKDet. The larger peaks are detected, usually without glitches, but the smaller pulses within the complex-repetitive pattern (hereafter 'micro-peaks') are often undetected, depending on the ratio of their closing peak to that of the highest closing peak in the token (used as a reference by PeaKDet). As a consequence, the complex-repetitive pattern can be detected in either of two ways: (i) if the micro-peaks go undetected, PeaKDet outputs values for one long cycle, as if it were single-pulsed creak; (ii) if at least one of the micro-peaks is detected, PeaKDet outputs a sequence of a moderately long cycle followed by a super-short cycle, incorrectly giving the visual impression (on a display of f 0 dEGG values) of considerable jitter or aperiodicity.

A semi-automatic workflow using PeaKDet (as was applied in the present work) might look like a solution in this case. The user can adjust the threshold for detection of closing peaks, so that the micro-peaks are detected. However, in practice this is not an optimal solution (maybe not even a feasible solution at all). Not only does it take a lot of time and effort to process the items: there are cases where this solution simply does not work technically. The closing peak amplitudes (DECPA values) for micro-peaks can be so low that lowering the threshold to capture them results in the detection of spurious peaks at other points within the glottal cycle: multiple closing peaks can be higher than the micro-peaks. A manual workaround consists in lowering the threshold, catching all micro-peaks along with spurious peaks, then merging the latter one after the other. That method is not only tedious: it also comes along with biases, since the more work is done manually, the more likelihood there is of user bias, artifacts and user errors creeping in. Clearly, PeaKDet was not devised as a tool to address such cases, and the way to go here would be to change the computer code, using a different algorithm.

Additionally, a challenge is encountered in terms of precision, as detection based on oscillation in f 0 and O q from one pulse to the next will also include phenomena that are not instances of creaky voice. Delta f 0 is technically known as jitter: the cycle-to-cycle variation of fundamental frequency. Interestingly, jitter is not only found in multiply-pulsed creak, but also in a phonation type known as harsh voice. Harsh voice is described by Laver (1980, p. 122) as somewhat similar to creak but in higher fundamental frequency. Harshness is distinguished from creakiness in the doctoral dissertation of [START_REF] Michel | Vocal fry and harshness[END_REF] (he use the term "vocal fry"). Figure 5.1 is an example of a syllable rhyme containing a jittery passage. The syllable is /laj²/ (bearing a phonologically non-creak tone) in blue curve. The speaker is F12; her signals frequently exhibits such jitter, in all tones. The signal throughout Figure 5.1 exhibits a slight long-short alternation in glottal cycles that resembles the complex-repetitive pattern of multiply-pulsed creak. However, the differences between successive pulses are much less salient than in multiply-pulsed creak. A saw-like shape can be observed in f 0 dEGG and O q dEGG , but again, with less salience (differences in f 0 dEGG below 30 Hz, and almost negligible in O q dEGG ). In addition, the values of these two parameters does not reach down into rock-bottom values as it does in creak. The contour of f 0 dEGG is within the range from 220 Hz to 160 Hz, and O q dEGG values are located around 55%. This agrees with the description of f 0 dEGG value in [START_REF] Michel | Vocal fry and harshness[END_REF], Michel andHollien (1968), andMichel (1968).

Thus, distinguishing jitter as exemplified in Figure 5.1 from the telltale complexrepetitive pattern found in multiply-pulsed creak need not be seen as an impossible task (drawing a line in the sand). A threshold in the rate of f 0 dEGG change has the potential to solve the technical issue, given that this parameter reaches higher values in multiply-pulsed creak.

However, since a threshold in f 0 dEGG change is also used as a common prerequisite condition for identifying creak (of any sub-type), a further distinction needs to be made in order to tell cases of multiply-pulsed creak apart from cases with less drastic change in f 0 dEGG : as in harsh voice, as has just been mentioned, and also in pressed voice (about which more below), which has the smallest change of f 0 dEGG in comparison with other sub-types of glottalization. Technically, this is a limitation of using a hierarchical tree structure in detection and classification ("if delta f 0 is above threshold T, this is a case of creaky voice, otherwise not; further sub-classification depends on…"). For a well-rounded technical solution, the conditions should be set independently of each other. They are then combined to identify each sub-category: identifying a certain phenomenon, such as multiply-pulsed voice. These categories can be grouped later as appropriate, e.g. defining the higher-level category of creak as a case of either multiplypulsed voice or single-pulsed creak or pressed voice. This topic will be taken up again in the section that discusses the detection algorithm ( §5.3).

Type 3: Aperiodic creak

This type corresponds to aperiodic voice in the terminology put forward by [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]:

Another variant of F0 irregularity is when it is taken to the extreme -vocal fold vibration is so irregular that there is no periodicity and thus no perceived pitch. Like multiply pulsed voice, aperiodic voice lacks the prototypical property of low F0; instead, the property of irregular F0 is enhanced, and the voice is therefore noisy. This also seems to match closely the characterization of aperiodicity proposed by Redi and Shattuck-Hufnagel (2001, p. 414): "irregularity in duration of glottal pulses from period to period".

An example of what we call aperiodic creak is provided in Figure 5.1. It has a smooth start with a steady, linear decline in f 0 dEGG from first to 15 th cycle, and then it becomes as aperiodic as can be. The electroglottographic signal is especially welcome here as a complement to the audio, in order to understand what is happening in detail, glottal pulse after glottal pulse. From the electroglottographic signal, it is obvious that shape and duration differ greatly among successive cycles. No pattern stands out clearly: the longer and shorter cycles are arranged in no particular order, as opposed to their neat organization into alternating patterns in multiply-pulsed creak. Such electroglottographic signals constitute a challenge for the PeaKDet script (and even for human eyes) to detect precise closing and opening peaks, as glottalization plays out the full gamut of its jarring, aperiodic, chaos-like score. The measurement of glottal open quotient is barely applicable in this case: using the current state of PeaKDet (essentially unchanged since first release: version 1.3.2 through 1.4.2 in the Covarep repository,2 corresponding to version 1.0 in the master repository),3 cherry-picking any of the O q dEGG values within the portion of aperiodic creak in Figure 5.1 would seem unreasonable. Judging from the shape of the electroglottographic signal, none of the cycles can safely be hypothesized to be divided into a closed phase followed by an open phase -even if one were to loosen greatly the definition of what "closed phase" and "open phase" mean. Theoretically, detection of this sub-type of creak could be based on the detection of micro-cycles. Following as closely as possible the chaotic patterns of glottal pulses would bring out the irregular, sudden increase or decrease of cycle lengths (still referred to as "f 0 dEGG " for short, with the very explicit caveat that what is meant thereby is not really a frequency, since it is calculated cycle after cycle, with no condition on repetition in time). By bringing out those cycles, the portion during which aperiodic creak occurs would stand out. However, my budding programming skills are not up to the task of creating an algorithm for detecting irregularity (lack of periodicity). Instead, as a first pass I chose to use the simplest method: by exclusion. That is, when there are sudden and salient changes in f 0 dEGG , but no complex-repetitive pattern is captured, the item will be classified as belonging to the sub-category of aperiodic creak. Of course, other conditions also need to be added to increase the precision. For instance, it seems highly likely that high dispersion of O q dEGG (values of O q dEGG that are scattered all over the place in the raw output produced by PeaKDet) could in many cases serve as reliable evidence to help to classify this sub-type. Such explorations are left for later work.

Type 4: Pressed voice

Inclusion of pressed voice inside an inventory of types of glottalization is controversial. Fortunately, there is a handy reference here, which simultaneously lends some legitimacy to the proposal, and formulates it in a clear and cogent way, placing it in an area that is phonetically adjacent to creak, and phonologically (cross-linguistically) within the space of allophonic variation of phonological creak.

When the glottis is constricted, but the f 0 is neither low nor irregular, a tense or pressed voice quality is heard. While not always considered a form of creaky voice, it can function phonologically as such in languages in which a creaky (or laryngealized) phonation can co-occur with high tone.

Here the constricted glottis is criterial. [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF] Considering the simplicity of the signals (audio as well as electroglottography) for pressed voice, this phonation type should in all logic be discussed before multiply-pulsed creak and aperiodic creak: in fact, it could deserve to appear at top of list, as the simplest phonation type -only a modest departure from modal voicing. The reason why it appears last in the inventory proposed here is that the focus is on creaky phonation: from the point of view of general phonetics it would not make great sense to consider pressed voice as a sub-type of creaky voice. The logic followed in the present research, following the proposal by [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF], is thus phonological (tonemic) rather than phonetic: pressed voice in the Muong dialect under investigation is among the frequently occurring phonation types in the phonologically creaky tone (Tone 4). It is therefore listed here as a fourth type of "creaky voice", in a perspective which admittedly departs from the perspective of general phonetic nomenclatures, but which, I hope, nonetheless makes an indirect contribution to a better understanding of creak as a general phonetic phenomenon, by helping shed light on the dynamics of a phonological system that uses glottalized phonation as part of a lexical tone.

As was done above for single-pulsed creak, two extreme examples are provided in order to show the extent of variation in this sub-type. Phonetically, it seems safe to hypothesize that there is a continuum between these two cherry-picked examples. They are examples of exactly the same target syllable /paj⁴/ spoken in isolation by the same speaker (F21) and in the same recording session, but the first was on the first repetition and the second on the second repetition. Auditorily, the first example sounds much more clearly pressed than the second. It is reasonable to assume that the consultant tended to pronounce the word in a hyper-articulated way in the first performance, then relaxed somewhat and said it with less hyper-articulation the second time.

The first example in Figure 5.1 can be described as a textbook sample of pressed voice since the glottal tension is clearly reflected in all signals in Figure 5.1a: the three signals all have a bottleneck (decreased amplitude) in the middle of their time course, from the 15 th to the 20 th centisecond. The amplitude of the audio signal is very notably reduced, which constitutes evidence that the vocal folds are strongly adducted, thus impeding the passage of airflow for a brief span during this strong adduction, before allowing a modest return in the second half. The return in the final portion is almost as great as that at the beginning in both the EGG and dEGG signals, but is much smaller in the acoustic signal. The strong constriction caused a challenge for PeaKDet to detect the closing and opening instants on the dEGG signal, since the amplitude of the corresponding peaks in the derivative of the EGG signal, which serves as a basis for detection, is so much lower (see bottom of Figure 5.1a). In this example, PeaKDet missed two cycles: it erroneously detects three cycles as a single cycle, the 18 th , as can be seen in Figure 5.1c. The corresponding spurious f 0 dEGG value detected is at 20 Hz (as shown in Figure 5.1b). This problem is solved by visually locating a more accurate threshold and setting the threshold manually in PeaKDet, so that the algorithm detects the small, undetected peaks within the spurious 18 th cycle. By modifying this threshold, PeaKDet will recalculate both parameters (f 0 dEGG and O q dEGG ), as shown in Figure 5.1d. 4 The f 0 dEGG curve now has less of a dagger shape at its lowest point, although it retains a remarkable, pointed trough around a lowest value of 60 Hz.

There was an interesting discussion about this example between me and my supervisor. He thought that he would tend to classify this example as a single-pulse creak rather than a presser voice as my opinion because the glottal cycles are lengthy and irregular during the glottalized portion. This is indeed true and appropriate from a theoretical perspective based on signal observation. However, from a perceptual standpoint, although I have not done a perceptual test so (c) Two parameters automatically calculated by PeaKDet: f 0 dEGG (green) and O q dEGG (blue and orange).

(d) Two parameters after resetting the threshold at 0.001 to catch two undetected closing peaks. In addition, I think the medial bottleneck in all the signals in Figure 5.1a must reflect something related to a sudden, brief and severe constriction of the glottis, which is not encountered in the other sub-types classified here.

In fact, several possibilities for classification are open here: this example compounds characteristics from single-pulsed creak and pressed voice. Not all cases fit into sharply delineated categories like single-pulsed creak and multiply-pulsed creak. There is a continuum in at least three criteria, which, together, make for a complex space (rather than one linear continuum): (i) the degree of glottal constriction, (ii) the regularity of damped pulses, and (iii) the duration of the constriction. Some cases like this one are best described in terms of a set of parameters, rather than just in terms of belonging to one category.

This explains my decision to have a place for pressed voice in the sub-classification of creak. Although perceptually different, pressed voice is closer to glottal constriction and even glottal stop than to creaky voice, but in its essence of glottis setting which reflected in acoustic and electroglottographic signal, they are closely related and difficult to separate in some cases. In other words, it could be said that pressed voice borders on creak, in the sense that they share certain phonetic characteristics and pressed voice can function phonologically in which a creaky phonation can co-occur. This is indeed the case in Kim Thuong Muong when the creak voice and the pressed voice are considered as two allotonic variations occur in Tone 4.

The second example of pressed voice is shown in Figure 5.2. It constitutes a case where the strength of vocal fold compression looks much less than in the previous example. If the first example is a maximal case of pressed voice, this second example is in contrast a minimal case. The evidence of pressed voice can be seen most clearly in the acoustic signal with a maximum reduce early after a short start in the state of modal voice. It is maintained until the end. The dEGG signal also presents a bottleneck corresponding to the most constricted part. The amplitude of EGG signal on the other hand does reflect any obvious change but some longer cycles can be noticed. The calculated fundamental frequency does not drop to very low values as in the ideal example. The bottom of the shallow valley in the f 0 dEGG curve is above 100 Hz. The parameter O q dEGG is measurable around 50%. These parameters do not reveal a glottalization phenomenon. In other words, they do not differ from those parameters normally measured in the modal voice. The clearest evidence to argue that this is an item of pressed voice is the damping of the acoustic signal.

We have also provided two other examples of pressed voices in a Github repository (here) that offers a gallery of examples of glottalization. The repo, which was elaborated in parallel with the work on the present thesis, offers a brief summary of materials set out in this section: it shows electroglottographic and acoustic signals with a discussion of various phenomena of glottalization. likely to agree more readily to their description as instances of pressed voice, than for the signals in Figures 5.3 and 5.4 (reproduced from the GitHub repository). The latter signals could easily be categorized using labels other than pressed voice. Admittedly, the same point could be made about the token shown in Figure 5.1: authors who prefer to use the label "pressed voice" for a lasting voice quality setting may describe the glottal event as an instance of glottal constriction, rather than pressed voice. Clearly, there is no hard-and-fast divide between pressed voice and single-pulsed creak, and terminological choices will continue to vary. An advantage I see in the examples in Figure 5.1 and Figure 5.2 is that they clarify the range along the glottal stricture continuum that is referred to in the present work as pressed voice. These two examples represent the two poles of a continuum from maximum to minimally pressed voice. Needless to say, it needs to be kept in mind that signal shapes are not the full story of phonation types, and some less clear-cut cases are encountered: this topic will be taken up again later when discussing the topic of boundaries (junctures in the utterance) and their ties to phonation types.

As mentioned above regarding the continuum of single-pulsed creak, the relative similarities in the shape of the electroglottographic signal create difficulties in attempts to distinguish pressed voice from single-pulsed creak. Both appear among phonetic realizations of the glottalized tone; for this phonological reason, as also for phonetic reasons mentioned above, it appears reasonable to add pressed voice to a vast continuum that extends from strongly damped pressed voice (close to single-pulsed creak), to light pressed voice which, in turn, is close to modal voice. Therefore, we intentionally classify pressed voice as a sub-type of creak, although some pressed voice items are more close to modal voice than to typical creak (single-pulsed or multiply-pulsed). It could be more accurate to describe pressed voice as one of several (phonetic) variants in the realization of (phonological) creak -and we hereby repeat our adhesion to the proposal by Keating et al. mentioned at the outset of this section.

Detection of creaky voice from the electroglottographic signal

The above developments about nomenclature relative to creaky voice now make it possible to turn to the issue of the detection of creaky voice from the electroglottographic signal, to take a quantitative view of creak phenomena in the data set under investigation. The f 0 dEGG tracings in Figure 4.1 only provided an indirect view into creak, as a perturbatory phenomenon detectable through jagged (jittery) shape of averaged curves for Tone 4 as opposed to the four others. It appears well worth teasing out the creaky portion from the rest, instead of damping the creaky signal through across-the-board averaging with non-creaky portions. The classification provided above into four basic sub-types is used here as a reference.

(a) Signals. From top to bottom: (i) acoustic signal, (ii) EGG, (iii) dEGG, (iv) smoothed dEGG.

(b) Two parameters automatically calculated by PeaKDet: f 0 dEGG (green) and O q dEGG (blue and orange).

An easy problem, but paradoxically without an off-the-shelf solution

Creak detection from the electroglottographic signal is, in an important sense, an easy problem, yet there is no easy and off-the-shelf solution. The electroglottographic signal appears especially suitable for the detection of creaky voice [START_REF] Gao | Interdependence between tones, segments and phonation types in Shanghai Chinese[END_REF], since creaky voice involves a lot of rapid changes in vocal fold contact area, and moreover there is a large amount of vocal fold contact in creaky voice. The electroglottographic signal is less directly interpretable in the case of breathy voice, which, by its very nature, involves less adduction of the vocal folds, and -in typical cases -incomplete contact between the vocal folds even at the point in time where the vocal fold contact area is greatest. Creaky voice is first and foremost a matter of patterns of vocal fold contact, whereas whispery/breathy voice has stronger ties to airflow and aerodynamics. Visually, creaky voice is often not too difficult to make out in audio signals, and it is even much clearer in electroglottographic signals, as exemplified in Figures 5.1, 5.1 and 5.1. One would therefore expect that software packages for the detection of creaky voice from the electroglottographic signal would be available from one of the world's research centres in phonetics. But while there are available toolkits for the detection of creak from the audio signal [START_REF] Drugman | Data-driven detection and analysis of the patterns of creaky voice[END_REF][START_REF] Dallaston | Estimating the prevalence of creaky voice: A fundamental frequency-based approach[END_REF], at the time when the experiments reported here were conducted, there was, to the best of my knowledge, no available script for automatic detection of creak from electroglottographic signals. This may well be due to the fact that audio signals are much more abundant than electroglottographic signals, and industry applications requiring phonation-type identification deal with an audio input, without the luxury of having an associated electroglottographic signal.

There were several ways to go here: one was statistical modelling (machine learning), and another was 'deterministic' modeling: classical programming by rule. The latter may seem outdated in the age of Artificial Intelligence. However, it has advantages in terms of explicitness, which are suitable for linguistic exploration. (Not to mention the practical fact that it was clearly more within my reach to write computer code in a few lines over which I had control than to put together machine-learning software 'bricks' that are of great internal complexity.) This is not to say that I do not have an eye on the exciting prospects opened up by end-to-end toolkits in Natural Language Processing (as exemplified by [START_REF] Adams | User-friendly automatic transcription of low-resource languages: plugging ESPnet into Elpis[END_REF] for automatic speech transcription applied to language documentation): these prospects are considered as a central topic of further studies in the wake of the present dissertation.

Step 1: list of specifications

The first step when writing a computer script is obviously to outline specifications. In this case, here is what we aim at:

1. Detecting which tokens have the presence of creak (phonetically) 2. Distinguishing phonetic sub-types within creak (specifically: single-pulsed voice, multiply-pulsed voice, aperiodic creak, and pressed voice, as distinguished above)

3. Providing detailed temporal information on creak: its duration, and its beginning and end relative to the beginning and end of the rhyme (allowing for the calculation of a range of indicators such as the ratio of creaky portion to duration of the entire rhyme) The output can then be used for analyzing linguistic patterns of creaky voice in the entire data sets.

Step 2: writing and testing the Creakdet script

The algorithm in Figure 5.5 presents the process for detecting and classifying the different sub-types of creak described above.

In order to facilitate the understanding of the algorithm presented here, we will elaborate in turn on: (i) the input to CreakDet, (ii) the three initial conditions for detecting types of creak, and (iii) the output as viewed through simple descriptive statistics.

The input to CreakDet: The input material is the three-dimensional matrix yielded by application of PeaKDet to electroglottographic recordings, as described in Section 3.3.2. Out of the wealth of information in the results matrix, the first-pass version of the creak detector only uses f 0 dEGG , DECPA and time codes (beginning and end of each cycle). In future work, the information of O q dEGG is expected to contribute much to refining the detector. O q dEGG is very revealing about phonation types -that is, when it can be reliably estimated. As pointed out in section data processing (3.3.2, there are cases when O q dEGG can by no means be reliably estimated, either because the signal is too noisy or because the glottal cycle is not neatly divided into a closed phase followed by an open phase. Use of O q dEGG is therefore avoided for detection of those configurations that can safely be detected on the basis of f 0 dEGG alone. On the other hand, O q dEGG is central to the detection of pressed voice, for obvious reasons (recall from Section 5.2 that O q dEGG relates straightforwardly to the degree of glottal fold abduction).

Thus, in the first version of Creakdet (short for 'creak detection'), the parameter f 0 dEGG is primarily employed. The first and second conditions are defined based on the rate of f 0 dEGG change (or also known as the rate of delta f 0 ) which is calculated by the function in the listing 5.1 named 'fochange'. The output of this function can be seen to include three variables:

1. delta f 0 in Hz (MATLAB script in the listing 5.1 from 2 nd line to 5 th line): it is simply a calculation of the difference between the f 0 dEGG values of successive glottal cycles. The f 0 dEGG value of the current cycle is subtracted from that of the next cycle. The result of this variable can be positive or negative. 2. rate_delta f 0 (in %): after measuring the delta f 0 as a basis for further measurements, we move on to measure the rate of this change by dividing it by the f 0 dEGG of the current cycle, and multiplying it by 100 to convert the result into a percentage. 3. smoo_delta f 0 (in %): the name of this variable is kept short for convenience, and does not tell the full story. Two operations are performed here. First, in order In addition to f 0 dEGG , which provides information about the duration of glottal cycles (in visual terms: the width of cycles along the x axis of displays of the audio and electroglottographic signals), the output of the PeaKDet script also includes another parameter: "Derivative-Electroglottographic Closure Peak Amplitude" (DECPA for short), which provides information about their height (i.e. the y axis). DECPA is the amplitude of the peak on the derivative of the electroglottographic signal at glottal closure (Michaud, 2004a). DECPA is also referred to in the literature as PIC, for Peak Increase in Contact [START_REF] Keating | Phonation contrasts across languages[END_REF]. By using the same 'fochange' function but changing the input variable to DECPA, we obtained similar information to f 0 dEGG but for DECPA: the three variables become deltaDECPA, rate_deltaDECPA, and smoo_deltaDECPA. The combination of f 0 dEGG and DECPA allows for a detection of complex-repetitive patterns (in multiply-pulsed creak) that is based on two dimensions of the deviated electroglottographic signal. In a nutshell: the input data for CreakDet includes the parameters calculated and stored by PeaKDet (in particular the times, f 0 dEGG , O q dEGG , and DECPA) as well as some parameters derived from these: calculations over delta f 0 and delta DECPA.

The setup of the 1 st and 2 nd conditions on the rate of f 0 dEGG change. The rate of f 0 dEGG change is studied through the variable smoo_delta f 0 . The values of this variable in the Tone 4 examples provided as prototypes (typical examples) in Section 5.2 are compared with those found on other target syllables carrying other tones (in the same minimal sets) to set initial thresholds for detecting creaky voice. The Figure 5.6 is provided for this purpose. The smoo_delta f 0 values of each tone are represented using the color assigned to the tone as mentioned in Appendix C.

Since our focus is on creaky voice, a consistent characteristic of Tone 4 and only that tone (whereas the other tones are all modally voiced), the experimental approach consists in paying attention to differences between Tone 4 and the other tones.

However, to avoid reasoning within a narrowly dialect-specific perspective (and thus, ultimately, within a circle, as there is a risk that creakiness and Tone 4 gradually come to be used with the same extension), it is constantly kept in mind that the ultimate goal is to distinguish creaky voice from modal voice from a phonetic point of view. That is to say, one needs to remember that, even though creaky voice is a prevalent phonological and phonetic feature of Tone 4, that does not entail that every syllable carrying Tone 4 has creaky voice, nor that creaky phonation never appears in syllables with other tones.

Considering the smoo_delta f 0 of the tones in those seven examples, it is obvious that this variable fluctuates the most in Tone 4 (as one would have predicted, because creak is associated with disruption of quasi-periodic phonation). The first example of extreme single-pulsed creak (Figure 5.6a) is the only one where the smoo_delta f 0 curve for Tone 4 is constantly far apart from the curves for the four other tones, which are snugly close to one another (except for the very first detected glottal cycle and the last three or four cycles). The curve for Tone 4 is in a space of its own, as it were, with values above 20%.

In the other figures, the onset and offset parts of Tone 4 overlap, or at least are not too distant from the other tones (near bottom values, close to 0% f 0 dEGG change). It demonstrates that the creaky voice does not usually occur right away at the beginning of the carrier syllable's rhyme, and that it also tends to tapers off at the end. However, once the creaky voice sets in, the change of f 0 dEGG is quick and remarkable. In single-pulsed creak and pressed voice, this change is generally in the range between 10% and 25%, but can be as high as 50% in the case of extreme single-pulsed creak or just less than 5% in the case of minimally pressed voice. In the remaining two types, this variable is recorded at much higher values: 80% in the case of multiply-pulsed creak and even reaching values such as 250% in the case of aperiodic creak. This makes sense: the sudden change between long and short cycles (also called micro-cycles) in these two latter types result in extreme changes in the derivative (delta).

Other tones, by contrast, have relatively flat smoo_deltaf 0 dEGG curves, often in the range from 0% to 5%, as can be observed in all the following figures: 5.6a, 5.6b, 5.6c, 5.6d, 5.6e, and 5.6f. However, noticeable changes of f 0 dEGG can occasionally be spotted in tones other than Tone 4. For instance, the second half of Tone 3 in Figure 5.6a has delta values at about 8%. Another token of Tone 3, shown in Figure 5.6f, has a short portion which reaches 10%, just before the offset of voicing. Notably, in Figure 5.6g, besides Tone 4 which has a remarkable f 0 dEGG change at nearly 100%, all other tones also show some fluctuations, in the range of 5% to 15%. Once again, Tone 3 is the second most 'jittery' tone (after Tone 4): a change on the order of 20% is found in the middle part of this token of Tone 3. This is common in data by speaker F7, a speaker who has an electroglottographic signal with great jitter in all the tones.

Another observation can be made that the final glottalization is prevalent in both elicitation contexts: in isolation as well as inside the carrier sentence, although it is more frequent in the former context. This phenomenon is revealed by a great and rapid rise in instability towards offset of syllables. The duration and the magnitude of the rise varies, but there are general trends nonetheless. It frequently happens over the course of just a few final glottal cycles. The change can remain below 10% (as in the case of tokens of Tone 4 and Tone 5 in Figure 5.6e), but it is usually above 20% (for instance, such is the case of all the tones in Figure 5.6g), and even getting above 150% as in the token of Tone 5 in Figure 5.6d.

By examining all the sub-types of creak that have been characterized here, in comparison with other tones in non-creaky voice, the key characteristic noticed is that the loss of periodicity in creaky voice causes rapid and abrupt changes in the fundamental frequency. Therefore, the first and the second conditions based on the rate of f 0 dEGG change (i.e. in the variable of smoo_deltaf 0 dEGG ) are established to catch the earliest signs of this phonation type.

The 1 st condition: threshold of smoo_deltaf 0 dEGG is set at 10%. In fact, the value initially considered for this threshold was 5%, because it allows the detection of most types of creaky voice, even pressed voice, while still excluding modal voice, where this parameter mostly remains under 5%. However, the precision and recall of this threshold are poor because there is a great deal of false positives: jitter in f 0 dEGG is common, and the fact that the script used for estimating f 0 dEGG is cycle-based, not autocorrelation-based, makes the presence of mild jitter especially prevalent in its output. It is not highly uncommon for jitter to reach rates of up to 15% (without a lapse into creak), as in the example shown in Figure 5.6g. Besides, some cases that constitute instances of light pressed voice (and thus, of "creak" in the sense used here) are not detected. The case of minimally pressed voice in Tone 4 (Figure 5.6f) will not be detected using a 5% threshold since the rate of change is only from 2 to 4%. The decision to raise the threshold to 10% instead of 5% means that such cases of pressed voice need to be detected by other means. This makes sense since we can really prioritize the detection of ' real' creak at the first stage and continue later on the further detection of the pressed voice which is relevant but not classified in the package of sub-type of creak. Setting the threshold at 10% leads to greater precision. An undesired consequence is that more cases of pressed voice will go undetected by this method (and this will need to be compensated by using other tools), but a desirable consequence is that fewer cases of mild jitter will be caught in the net. All in all, the threshold at 10% makes good sense for detecting phonetic phenomena of creaky voice. Pressed voice, with a change in f 0 dEGG less than 10%, is closer to modal voice in the continuum of single-pulsed creak -pressed voice -modal voice; and strong jitter, with a change in f 0 dEGG greater than 10%, is really close to double-pulsed creak in terms of signals (both acoustics and electroglottography) and perception.

In short, this condition preliminarily separates creaky voice from non-creaky voice, with two clear and allows two existences: (i) the pressed voice close to the modal voice will not be included, (ii) the great jitters will be included.

The 2 nd condition: threshold on smoo_deltaf 0 dEGG at 20%. This condition aims at continuing to separate muli-pulsed creak and aperiodic creak from the four sub-types of creak which were initially filtered out by the first condition. From the observations in Figure 5.6, it can be noticed that generally, the more irregular the periodicity is in the sub-types of creaky voice, the more remarkable is the smoo_deltaf 0 dEGG values. Indeed, in two examples of Figures 5.6c and 5.6d, the smoo_deltaf 0 dEGG values of Tone 4

are recorded prominently at 80% and even up to 250% in cases of double-pulsed creak and aperiodic creak, respectively. The 80% to 90% values of those two syllables are higher than 20%. Whereas, the other examples, this variable generally does not exceed 20%. The example of maximum pressed voice in 5.6e has only one value at cycle 16 th located above 16%. The extreme single-pulsed creak in Figure 5.6a is an exception, with all values in the range of 20% to 50%. Technically, this example will be detected and classified along with the second basket of muli-pulsed creak and aperiodic creak at this stage of the second condition. Thus, it shows that there are still flaws in the separation of the sub-types of creak. As a result, the recall of CreakDet version 1 will not be high. Apparently, the condition on the threshold of the rate of f 0 dEGG change basically distinguishes the creaky voice from the modal voice, but it is not sufficient to enable the classification of all the different sub-types. Therefore, the third condition on the direction of f 0 dEGG change and DECPA change is added to continue this task. Note that while DECPA does not have a linear relationship to acoustic intensity, there is still a strong relationship between the two.

The 3 rd condition: based on the particular characteristics of multiply-pulsed creak to set apart this sub-type from aperiodic creak. The most obvious feature of double-pulsed creak is the alternation of short and long cycles (the starting cycle can be either a % short or a long cycle) in a great change of fundamental frequency. This characteristic has been broadly recognized by numerous previous works such as: "double pulsation" in (Paul [START_REF] Moore | Dynamic variations of the vibratory pattern in the normal larynx[END_REF], "double glottic pulses" in [START_REF] Hollien | Perceptual study of vocal fry[END_REF] and [START_REF] Hedelin | Pitch period determination of aperiodic speech signals[END_REF], [START_REF] Roubeau | Laryngeal vibratory mechanisms: the notion of vocal register revisited[END_REF], etc. The other also mentioned the possibilities of triplet cycles [START_REF] Blomgren | Acoustic, aerodynamic, physiologic, and perceptual properties of modal and vocal fry registers[END_REF] or higher multiples [START_REF] Keating | Acoustic properties of different kinds of creaky voice[END_REF]. In the current study, triplet cycle patterns were not found, hence we only address here the case which we call double complex-repetitive pattern.

The third condition is actually a combined condition containing three sub-conditions that are applied simultaneously by the "and" command, including: (i) condition on the zigzag pattern; (ii) condition on the similarities between second nearest cycles; and (iii) condition on dissimilarity of adjacent cycles.

Sub-condition #1: condition on the zigzag pattern (Line 82 in List 5.3). The name of this sub-condition reflects the shape of f 0 dEGG modulation in multiply-pulsed creak, as shown in the example in the Figure 5.1. The alternation of short and long glottal cycles corresponds to the alternation of high and low f 0 dEGG values. As a consequence, it leads to alternating positive and negative delta f 0 values. To catch this kind of pattern at each syllable, a loop is created to consider delta f 0 across windows of four successive cycles, testing whether there are alternations of positive and negative delta f 0 . Such alternations are marked as positives of zigzag pattern (see line 82 in 5.3).

Sub-condition #2: condition on the similarities between second nearest cycles, in terms of f 0 dEGG and DECPA ). This condition is based on the rate of change of f 0 dEGG and DECPA for a two-dimensional verification of each current cycle with its second nearest one. The calculation is similar to the equation of rate_deltaf 0 dEGG in the "f 0 dEGG change" function since it is in fact an opposite relationship: the more similar, the less different. In the same window of each four successive cycles as the first sub-condition, the cycle at the position k is subtracted from the cycle at k+2 in absolute value for an easier comparison, then the result is divided for the smaller value between k and k+2. The same calculations are applied to k+1 and k+4.

The idea of this condition is to catch the telltale characteristic of aperiodic creak. The hypothesis is that aperiodic creak has much higher values in this variability index than all the other types, as a consequence of completely irregular glottal pulses. The simple detection script might have a few false positives corresponding to big jumps found in transitions into (and out of) multiply-pulsed creak, and also in some cases of single-pulsed creak (as in the example in Figure 5.1), but generally they are nowhere as salient as aperiodic creak. Therefore, in order to exclude aperiodic creak and keep only multiply-pulsed creak, we set the threshold on this condition at less than 0.2 for all f 0 dEGG and DECPA change of second nearest cycles.

Sub-condition #3: Condition on dissimilarity of adjacent cycles (Lines 91-96 in List 5.3).

The journey towards the creation of the third condition had actually begun before the CreakDet function was written out. In the initial tests, in order to detect the complex-repetitive pattern, we created a function called "CRPdet.m" (as can be seen in List 5.2) with two conditions applied simultaneously. If there are alternations of positive and negative delta f 0 (i.e. a zizag pattern) and the change of smoo_deltaf 0 dEGG in these cycles is equal to or greater than 20% (i.e. the 2 nd condition is met), they are detected as positives of complex-repetitive pattern in double-pulsed creak. This function is tested in all the samples we took in the first step of identifying the sub-types of creak. The focus is on three samples, respectively illustrating (i) double-pulsed creak, (ii) jitter, which has similar characteristic of zigzag pattern but has a much smaller change in smoo_deltaf 0 dEGG , and (iii) aperiodic creak with an unexpected change in glottal cycles. Figure 5.7 provides the demonstration of how CRPdet function worked on those three samples.

In order to understand that figure, it should be noted that the main demonstration is displayed in the top sub-figure with two conditions (zizag pattern and threshold on rate_deltaf 0 dEGG ) and the electroglottographic signal below to reflect the detection of these conditions on corresponding glottal periods. The two conditions applied in "CRPdet.m" are reflecting in coloring, to illustrate which values are positive or negative, i.e., whether they meet the conditions or not. In particular, the condition of zizag pattern is presented in magenta and green circles. It turns green if the window of four successive deltaf 0 dEGG values meets the condition, otherwise it remains magenta. The result of detection is stored in the first cycle of the window. This means that for any green cycle in the figure, there is a positive zigzag pattern of four successive values, starting from that value. At the same time, the detection of a positive zigzag pattern is reflected in the electroglottographic signal below by five green dots located near the beginning (closure instants) of the corresponding glottal periods. This is due to the fact that each deltaf 0 dEGG value is calculated by two values of f 0 dEGG , a window of four successive deltaf 0 dEGG values therefore involves five values of f 0 dEGG . If one or more values in the window do not meet the condition, the window will be detected as a negative zigzag, shown by a magenta cycle at the first deltaf 0 dEGG value, and will not be marked in the electroglottographic signal.

Similarly, the condition on smoo_deltaf 0 dEGG variable is represented by red and blue asterisks for positive and negative, respectively. The red line at 20 indicates the threshold that is set for this condition. All values of smoo_deltaf 0 dEGG that reach or cross this line are marked in red, otherwise they are in blue. Since a value of smoo_deltaf 0 dEGG is calculated from five f 0 dEGG values as the formula in 5.1, a positive value corresponds to five f 0 dEGG values, i.e., five glottal period is detected, as they are marked in blues dots in the electroglottographic signal. The negatives, on the other hand, are marked with blue asterisks in the display part of this variable but are not marked in the electroglottographic signal.

In the electroglottographic signal, if red and blue dots are marked in the same cycle, it means that the cycle meets both conditions of the zigzag pattern and that the smoo_deltaf 0 dEGG is equal to or greater than 20%, and is therefore detected as a cycle belonging to the complex-repetitive pattern. At least five successive cycles will be detected for a minimum interval.

As can be seen in Figure 5.7, CRPdet.m works pretty well on the sample of multiplypulsed creak since it caught the long span of double-complex repetitive pattern in the middle. There are six cycles early in the beginning (from 15 th to 20 th ) and four cycles at transition positions (two before and two after at the 30 th and 31 st cycles, and 73 th and 74 th cycles, respectively), which are positive with the zigzag pattern but negative with the smoo_deltaf 0 dEGG condition. Therefore, they are not counted as instances of complex-repetitive patterns. This is reasonable because the first six cycles are just a very short and light jitter at the beginning of modal voice before entering into creak. Four cycles in transitional positions between modal voice and creaky voice are in a borderline situation.

In the case of jitter in Figure 5.7b, the function also did well in not detecting this type of signal as a complex-repetitive pattern, with none of the cycles meeting both conditions. It is predictable that some portions would be positive with the zigzag condition since the shared characteristic of jitter and multiply-pulsed creak is the alternation of long-short glottal cycles but to varying degrees. Indeed, in the jitter sample here, a short portion right at the beginning (at cycles 1 st to 9 th ) and a long portion (at cycles 18 th to 48 th ) are marked as positives of zigzag pattern, but both of them and even the entire syllable are negative with second condition, i.e., their change of smoo_deltaf 0 dEGG is always less than 20%.

The sample of aperiodic creak in Figure 5.7c, on the other hand, highlights an issue: that during the presence of creak event, some discrete portions are detected as positive of complex-repetitive pattern. Among them, the first one consists of two cycles, the 9 th and 10 th . It seems that these are points of intersection between two different portions: (i) cycles from the 5 th to the 8 th meet the condition of zigzag pattern but (c) Some detailed information on the detection of CreakDet version 1 in seven tones across twenty speakers. Figure 5.8a shows the ratio of cycles detected as creaky (any sub-types) by CreakDet (version 1), to the total number of glottal cycles (n = 426,676), sorted by tone. For testing at this stage, we initially analyze tokens spoken in a carrier sentence (i.e. the target syllables extracted from the carrier sentence). Later, isolated tokens can be similarly analyzed, for comparison. Tokens are pooled across all speakers, and hence also across genders. It is obvious to notice that the creak ratio thus computed is by far higher in Tone 4 (the creaky tone) compared to all other tones. While no other tone has a creak rate greater than 5%, Tone 4 alone exhibits this extremely prominent rate above 30%, providing further evidence of the close association of phonetic creak (as detected through the procedure explained above) with Tone 4 as a lexical tonal category.

However, there is clearly still further work to be done to improve the precision of these results. If blue color on Figure 5.8b were only found for Tone 4, it would be a reliable guide to identification of the tone. But since blue color is not found exclusively on Tone 4, creak in the sense of that figure (detection by CreakDet) is not specific to Tone 4, and it is an issue how it can function as a major cue in tonal identification.

Obviously, the next question is how to progress from detection of creak in the most general phonetic sense to the patterns of creak specific to Tone 4assuming that such patterns can be identified, of course. Temporal information is likely to matter in the move that consists in teasing apart different phenomena within the blue-colored cases in Figure 5.8a. The blue color pools together longer creaky stretches and short glottalization phenomena, because both share the characteristic of having dramatic change in fundamental frequency. The conditions of delta f 0 rate, setting a threshold at 10% and 20%, does not eliminate the cases of onset and offset glottalization. In Muong as in many (all?) other languages, glottalization can occur at junctures in the utterance (such as phrase boundaries). Functionally, this intonational phenomenon is on a different level from phonological specifications of the lexical tones. Luckily for my study, the difference is fairly neat from a phonetic point of view, too. I hypothesize on the basis of memories from processing all the syllables (as part of the semi-automatic workflow) that the marking of junctures is located with some precision at the end of the last syllable before the juncture (at the juncture), whereas the lapse into creaky voice typical of canonical Tone 4 occurs much earlier in the syllable rhyme. Under this hypothesis, it should be possible to tease apart two sharply different subsets within CreakDet's creak results. One is final glottalization, occasionally observed on any of the tones, and the other is the typical lapse into creaky voice found in Tone 4. (Cases of short, initial glottalization as part of coarticulatory effects after certain initial consonants will need to be dealt with separately.)

Now moving on to clarify my intuitive sense that there are salient differences (obvious to the trained eye) in terms of position and duration. The stretch of initial or final glottalization due to the marking of junctures is brief; as an initial test, it seems reasonable to try a temporal dividing line at five cycles at the onset or offset and consider that longer stretches belong to bona fide creaky voice. One of the bases for this initial choice is that, as a rule of thumb, "phonologically real" creaky voice in Tone 4 lasts from about 10 to 15 cycles (with an average around 13 cycles).

Version 1 of CreakDet still needs to resolve some remaining issues. Besides the issues of glottalized onset and offset just mentioned above, the next thing that will need to be noticed and addressed is that pressed voice, which is known from the sifting of examples to be well attested among allotones of Tone 4, is not treated adequately by CreakDet version 1 (whose main focus is on phonetic creak). Already in the first condition on smoo_deltaf 0 dEGG , the threshold of 10% excluded many cases of mild to minimally pressed voice as in the sample shown in Figure 5.2. Therefore, a further solution will be needed to improve the detection of pressed voice and provide a full picture of glottalization.

In a nutshell, at the current stage of the script for creak detection, CreakDet (version 1: April 2021), the detection is based on three simple conditions listed in Section 5.3.3. There is still a range of issues that need to be addressed further down the road: more conditions will be added and existing conditions will be modified in the next versions. The final goal is to obtain a result that contains the information about the creaks detected from the input data as precisely and elaborately as possible. Work that cannot be done in this ongoing study will be opened for further continuation.

Glottalization in Kim Thuong Muong: phonetics and phonology

In light of the above developments, the time now seems ripe for summarizing key facts on the phonetics and phonology of glottalization in Kim Thuong Muong.

As has been mentioned at several places in this thesis, and as can be seen clearly in Figures 4.1 The evidence examined here suggests that f 0 dEGG ensures the bulk of the tonal distinctions in Kim Thuong Muong, whereas O q dEGG is only relevant insofar as it discriminates the glottalized tone from the remaining four tones (modal tones). Moreover, the glottalized tone is also the lowest of all five tones in terms of pitch, so that pitch and phonation could be said to stand in a simple relationship of co-occurrence or correlation. The correspondence between pitch and phonation in this tone system is as expected from a typological point of view: higher pitch corresponding to modal (non-creaky) voice, and lower pitch (bottom values) corresponding to glottalized/creaky voice.

In this light, one could even wonder whether glottalization needs to be granted phonological status at all. The fact that glottalization occurs on the phonetically lowest tone in Kim Thuong Muong raises the issue whether this glottalization may not be a low-level phonetic phenomenon associated to a low (or extra-low) phonological target.

But a clear answer in the negative can be provided. The data set out in Chapter 4 reveals that the phasing of glottalization in Kim Thuong MuongTone 4 is precisemuch more precise than would be expected if this were simply a low-level phonetic phenomenon. Moreover, the association of glottalization to Kim Thuong MuongTone 4 is highly consistent: glottalization is a robust feature of Kim Thuong MuongTone 4, also found in contexts where speakers raise their voice. Qualitative data observation suggests that the phonetic realization of glottalization is slightly different when the utterance's overall pitch is higher, with less creaky voice and more constriction, but glottalization is still present. Furthermore, if the glottalized tone were underlyingly (phonologically) specified simply as having an extra-low pitch target, and if glottalization were only a low-level phonetic consequence of this target, then one would expect the lowest tone to be sometimes modal, sometimes creaky, and also sometimes breathy. Breathiness is opposite to creaky voice along the continuum of vocal-fold adduction degree, but lapse into breathy voice could be seen as a low-level phonetic consequence of a low pitch target, in the same way as creaky voice. 5Thus, glottalization phenomena in Kim Thuong Muong are consistent with the typological tendency whereby creak is associated with lower pitch, but this typological tendency does not have the power to 'predict' glottalization phenomena in Kim Thuong Muong in full phonetic detail. The phasing of glottalization inside rhymes carrying Tone 4 does not result from low-level phonetic phenomena. The association of creaky voice to Kim Thuong MuongTone 4 can safely be interpreted as due to a phonological specification.

Said differently, pitch plays the main role in the Kim Thuong Muong tone system, but it is not the only phonologically relevant parameter.

To what extent these two acoustic properties -fundamental frequency and open quotient -contribute to the listeners' perceptual impression of the tones is a matter for future studies of speech perception to investigate. As an example of hypotheses to be tested in future work, it seems that creak with complex-repetitive patterns (to which Keating et al. refer as 'multiply pulsed') occurs frequently in canonical or hyperarticulated realizations of Kim Thuong MuongTone 4. It is a safe guess that reduction to less canonical creak is frequent in casual speech -a hypothesis which will later be tested through examination of other materials, such as narratives. (i) The position of glottalization:

Vietnamese dialectology as a source of inspiration for the study of Muong in general and Kim Thuong Muong in particular

• Kim Thuong Muong Tone 4 has medial glottalization: the glottalization of Tone 4 happens in the middle part of the rhyme. The tone starts in the lowest part of the speaker's f 0 range: its onset f 0 is the lowest of the five tones; f 0 then decreases sharply, revealing early glottalization; finally, glottalization is relaxed towards the end of the syllable, returning to f 0 values suggestive of phonation mechanism I (chest voice).

• Vietnamese B2 has final glottalization: whereas f 0 curves of Kim Thuong MuongTone 4 can be analyzed into three portions (initial modal portion; glottalized portion; and final modal portion), Vietnamese B2 can be analyzed as consisting of two portions, with glottalization strongest at the end of the rhyme.

• Vietnamese C2, similar to Kim Thuong MuongTone 4, has medial glottalization, but the onset and offset f 0 values of tone C2 are not at the same level, whereas those of Kim Thuong MuongTone 4 are close to each other. The figure from Kirby (2011) reproduced here as Figure 5.9 shows that the beginning of Vietnamese C2 is high, and its end clearly much higher, at the top of the speaker's range. (ii) The values of f 0 : Differences in f 0 are relative, and are affected by many factors, such as differences across speakers and experiments. In order to get a feel for this difference, the evaluation of f 0 values of glottalized tones need to be conducted against the background of a comparison with the other tones in the system.

• Kim Thuong MuongTone 4 reaches very low values: it is consistently at the bottom of the speaker's range. Sometimes it can go down to values under 30 Hz Kirby, 2011, p. 386. in the case of most speakers. • Vietnamese B2 as see on Figure 5.9 has an f 0 curve in the middle of the speaker's range, lower than A1 and C2, and higher than A2 and C1. The f 0 values at the beginning of the rhyme are thus clearly higher than those of Kim Thuong MuongTone 4. • The difference between Vietnamese C2 and Kim Thuong MuongTone 4 is even greater: C2 is in the top of the speaker's range at both endpoints of its course, in contrast with Kim Thuong MuongTone 4 which is close to the bottom of the speaker's range throughout. The highest f 0 point of C2 reaches up to levels never seen for Kim Thuong MuongTone 4 (at least in the type of contexts examined here: careful, hyperarticulated realizations). (iii) Duration

• In Kim Thuong Muong, as explained above, pitch and phonation type are both important cues to distinguish between the tones, whereas duration by itself does not appear to play any major role to distinguish between the five tones of smooth rhymes. The duration of Kim Thuong MuongTone 4 (the glottalized tone) is similar to that of the four others; under the experimental conditions used here, the average duration is on the order of 25 centiseconds. • Vietnamese B2 is short. James Kirby's figure of the Vietnamese tones shows that the duration of B2 is only about half that of the other tones. The author comments that "[a]lthough duration has not been shown to be a salient perceptual cue to Vietnamese tone, syllables bearing tones B2 and C1 are often shorter than syllables bearing other tones due to the effects of final glottalization" Kirby, 2011, p. 386.

• The duration of Vietnamese C2 is similar to that of Kim Thuong MuongTone 4.

Overall, although the phonation types of Vietnamese B2 and C2 and of Kim Thuong

MuongTone 4 can all be described as glottalized, there are multiple differences between Kim Thuong MuongTone 4, on the one hand, and Vietnamese B2 and C2 on the other. In terms of the tones' position inside the tone system as a whole, the viewpoint defended here for Kim Thuong MuongTone 4 -that glottalization sets it apart from the other four tones of smooth syllables -could not apply to Vietnamese. Vietnamese B2 and C2 appear to have very different ties with the rest of the system. (This point need not be labored here, in view of the wealth of publications about the tone system of the Hanoi dialect of Vietnamese.)

The existence of deep differences does not mean that Vietnamese studies cannot provide inspiration for Muong studies and vice versa. The point that Northern Vietnamese tones "are realized by a complex of pitch and voice quality features" has been made eloquently by specialists of Vietnamese Kirby, 2011, p. 386; this also applies to Muong, saving specialists of Muong the trouble of laboring a point that has already been made for the closest relative of the Muong language. No less importantly, the issue of which specific phonation type (if any) is actually associated to each tone remains a topical issue in Vietnamese studies; this situation points to the difficulty of reaching definitive conclusions about which properties of a tone can be considered to be phonological, and how the tone should ultimately be modeled.

[G]lottalization plays an important role in the production and perception of the broken (C2) and glottalized (B2) tones. The falling tones (A2, C1) have been described by some researchers as accompanied by a breathy voice quality (Thompson 1965;Phạm 2001Phạm , 2003)); the low falling tone (C1) has also been described as accompanied by light final laryngealization (Nguyễn Văn Lợi & Edmondson 1998;[START_REF] Michaud | A measurement from electroglottography: DECPA, and its application in prosody[END_REF][START_REF] Kirby | Dialect experience in Vietnamese tone perception[END_REF]. Kirby, 2011, p. 386 These discussions about Vietnamese stimulate the search for other phonation types beside glottalization in Muong dialects. While this search did not prove fruitful for Kim Thuong Muong (although a few gender-specific trends were brought out in the Results chapter), it will definitely need to be kept in mind in future work on tone systems across Muong dialects.

An important point brought out by the comparison of Muong and Northern Vietnamese is that Kim Thuong Muong Tone 4 is to be recognized specifically as a creaky tone, a label that is more specific than just glottalized tone. As amply exemplified above, various sub-types of glottalization are attested in realizations of Tone 4 in Muong.

The question raised here is whether this tone should be recognized as a "creaky tone" or a "glottalized tone". Concerning the distribution of allotonic variants: in deliberate speech (tending towards hyper-articulation), Tone 4 is canonically produced with creaky voice, although glottal constriction is also attested. This helps place Muong in typological perspective. Muong is provisionally proposed as an example of a language having a lexical tone that includes creak as part of its phonetic/phonological template. Typologically, this canonical realization appears sufficiently distinct from the glottal constriction of Northern Vietnamese tones (final in Vietnamese tone B2, medial in Vietnamese tone C2: Brunelle, D. D. Nguyên, and K. H. Nguyên 2010) to warrant recognition as a separate type of glottalized tone. For this reason, we suggest to call Tone 4 as creaky tone, to distinguish it from constricted tones of Northern Vietnamese.

Some free associations around the glottalized tone (Tone 4)

As a concluding note about Tone 4, this paragraph tries to leverage methods that are not part of the standard toolbox of the phonetician. To justify the use of arcane symbols like the dollar sign and the pound symbol as diacritics for High tones in Yongning Na, Alexis Michaud argued that "desperate tones call for desperate measures" [START_REF] Michaud | Tone in Yongning Na: lexical tones and morphotonology[END_REF]. The simile does not really hold, as there is nothing desperate about Muong tones, unlike Na tone: the phonological patterns are essentially as expected within this branch of Austroasiatic (whereas Na is tonally very much unlike its otherwise close sibling Naxi: Na has morpho-tonology not found in Naxi). But the presence of phonation-type specifications within tone is nonetheless a situation that stands some phonological concepts on their head. Hence, a variety of approaches can still be useful, including some "freestyle" reflections of a somewhat literary (as opposed to technical) nature. Perhaps such reflections are even more useful since there are few phonological alternations to shed light on the phonological nature of the tones.

What is Tone 4 when all is said and done? So far, it has been referred to by a number, placing emphasis on the fact that the choice is conventional and could have been different. "Tone 4 " means nothing specific, beyond that the tone is part of a system. How to progress beyond this label? How to look at Tone 4 in a different way, calling it by its "real name"? In Shakespeare's Romeo and Juliet, Juliet's passionate denial of the importance of a name ("What's in a name? that which we call a rose / By any other name would smell as sweet") highlights even more sharply the real (sometimes deadly) importance of names.

Tis but thy name that is my enemy; Thou art thyself, though not a Montague. What's Montague? it is nor hand, nor foot, Nor arm, nor face, nor any other part Belonging to a man. O, be some other name! What's in a name? that which we call a rose By any other name would smell as sweet; So Romeo would, were he not Romeo call'd, Retain that dear perfection which he owes Without that title. Romeo, doff thy name, And for that name which is no part of thee Take all myself.

Names can be very telling, if one pays sufficient attention. In the case of persons, the relationship to names is especially vital and complex, but the names of tones too can bear an important relationship to the entity for which they serve as labels. Names given to tones (as to other linguistic entities) are intended to serve as handles to a certain linguistic reality (or fiction: a social creation). Why are the tones the way they are? That is not a fair question to ask speakers (although any question that opens an opportunity for an interesting answer can look legitimate in retrospect). But that is a question that can lurk in the consciousness of speakers of any language. Looking at names, and looking for names, can be interesting in this respect: names are intended to reflect the familiar 'feel' of tones.

The Vietnamese language encourages us to go in this direction, as it has names for all its tones. They serve as mnemonic, being instances of the intended tone (as also in traditional Chinese phonology), but they also convey a feel for the tone's identity. In historical Chinese phonology, tones have names, too, and these have been adduced in 21st-century research by Michel Ferlus: he uses the labels chosen by authors in medieval times to explore hypotheses about the phonetic realization of tones at the time, specifically suggesting that qù may have been a breathy tone (Ferlus, 2009). In this tentative exploration of Middle Chinese and its Old Chinese roots, the exercise consists in reflecting on the options among which the labels were chosen, and thereby retrieving (hypothetical) characteristics of the historical tones. For Muong, the exercise proposed here is to think about possible choices for the tones as synchronically attested.

We now know what Tone 4 sounds like, and we can choose a name for it, as one of various means to approach this phonological entity.

The names of Vietnamese glottalized tones are commonly known to speakers, from schooling. The glottalized tones are thanh nặng (etymological category: B2) and thanh ngã (C2). Nặng literally means heavy 'heavy', and such is the label adopted in Englishlanguage literature about this tone (i.e. translating the Vietnamese label). How is the tone heavy? What is its heaviness? What is the 'stuf' that its heaviness is made of? Is the low register in which tone nặng terminates 'heavy' by itself? Arguably not: the lowest tone in the system, huyền does not feel heavy, although it is defined by a low register. Instead, the heaviness of tone nặng has connotations of solidity. That tone is short (hence a feeling of smallness) but has strong glottalization, which makes it feel solid, somewhat like a ball of iron, which is small but heavy. Clearly, the connotation of solid weight, and hence of heaviness, comes from glottalization, and specifically, from glottalization that goes low and ends fast. The glottal gesture presses the tone to the floor, fast, and keeps it pinned there.

As for thanh ngã (C1), it is often referred to in the English-language literature as broken (e.g. by Kirby, 2011). As a speaker of Vietnamese, this label appears counterintuitive to me, as I do not feel that the syllable is actually broken. The tone is what makes it a complete syllable, fitting snugly inside the tone system: quite the opposite of breaking the rhyme, it makes it complete. Here we hit upon one of the paradoxes of glottalization: ngã is a phonological unit (a lexical tone) defined by discontinuityby a lack of internal unity, a breach of what speakers of English, French… feel as continuity.

Interestingly, the Vietnamese language does not label this tone as 'broken'. A handy term here would be gãy, which, as desired, exemplifies the intended tonal category. Instead, the Vietnamese name ngã means 'to fall'. (Part of the reason why it was not translated as 'falling' in English is because a falling tone, in English, is a tone with a falling contour of f 0 , drawing attention away from glottalization.) What kind of fall? It is not just an act of tripping, but actually a fall right to the ground (phonetically: the medial glottal constriction), followed by the act of rising up again (phonetically: the final, clearly rising part of the tone).

In Muong, colors were assigned to tones, and their feel described. Now is the time to elaborate on these intuitions, and make the most of them, also putting words on them. Ideally, the exercise would be carried out in the Muong language itself, finding words that exemplify the tonal category at issue. My command of the Muong language is still rather frail, but it is no reason not to try to play a game of Who-am-I, using various languages.

As a first go: Tone 4 feels like a boomerang, in that one throws it away, it goes out of hand (out of modal phonation, into creak), where it has a course of its own -which feels rather long -, then it comes back in again.

Tone 4 also feels like a sickle, due to its grating feel (again, due to creaky voice), like the feel of a sickle cutting through a handful of rice plants.

If it were a kind of stone, Tone 4 would be lava stone: light rather than heavy (and thereby unlike Vietnamese tone B2, the 'heavy' tone), and rough and grating with its solidified bubbles -like the bubbles of air coming through the closed glottis in creaky voice. (Remember from C that such was the reason why a red color was selected for plotting Tone 4.)

In Muong, a plausible label would be kuəj⁴ 'bottom'. An advantage of this label is that it does not focus only on creaky voice, thereby avoiding a potential bias of the present dissertation: paying so much attention to phonation type as to become somewhat obsessed by it and losing sight of the broader tonal picture. 'Bottom' refers to the position of Tone 4 at the bottom of the system. Thereby, this label also includes a reference to creak, which is what makes this tone a bottom tone, not just a low tone. I also like the familiar ring of 'bottom', suitable for a language spoken at the village by people who are not conceited and have a healthy sense of humor (including occasional overtones of self-deprecation). With this final comment, discussion of the tones is provisionally considered closed, and we move on to considerations about the interplay of tone and intonation.

Intonation in Kim Thuong Muong: the view from sentence-final particles

Some hints about intonation in Muong could be gleaned in the course of the study of monosyllables in a carrier sentence: even when the materials are 'well-behaved' tones studied in a highly controlled way, some insights into intonation can be gained, but in a fairly indirect way since the main focus is on the contrasts among lexical tones.

To offer further insights into the intonation of Muong, the present section adduces evidence from sentence-final particles: the one that appears in the carrier sentence, but also others that appear in fieldwork data. Sentence-final particles are a borderline case in terms of tone, so that their study can arguably offer insights into the interplay of tone and intonation.

Final particles and intonation in Southeast Asian languages, and the case of Vietnamese and Muong

Various languages of Southeast Asia, including Vietnamese and Muong, make abundant use of sentence-final particles, a marginal class of expressive words indicating speech act types, evidential/epistemic nuances, and affective/emotional coloring. There are about ten sentence-final particles in Mandarin, thirty in Cantonese [START_REF] Kwok | Sentence particles in Cantonese[END_REF], and about the same number in Vietnamese (Thi Hue [START_REF] Tran | Tinh thai giam nhe trong dien ngon tieng Viet [Attenuation in Vietnamese discourse[END_REF]. Sentence-final particles are ubiquitous in casual, conversational speech. Sentence-final particles "often carry much of the meaning and function that intonation does in non-tone languages" (Chan, 1998, p. 117). The relationship is not simply one of functional equivalence between intonation and sentence-final particles, however. Studies by [START_REF] Seitz | Relationships between tones and segments in Vietnamese[END_REF] and [START_REF] Do | Intonation in Vietnamese[END_REF] on Vietnamese indicate that if a final particle is removed, it is possible to compensate in part through intonation, but they also note the artificiality of the exercise. In both Muong and Vietnamese, the absence of particles in daily speech would clearly be abnormal, as particles play an important role in spontaneous speech. Moreover, sentence-final particles also carry intonational information, since sentencelevel intonational phenomena are known to cluster on sentence-final particles. One and the same sentence-final particle can take on different nuances (creating different sense-effects) depending on the intonational realization of the sentence-final particle itself (the 'tune' that it carries) and of the sentence as a whole. Sentence-final particles are so tightly linked to intonation that it is not immediately obvious whether they have a tone of their own or not: sentence-final particles are bound morphemes that can only appear sentence-finally, i.e. in a position where intonational phenomena are known to abound. This makes it difficult to test experimentally for inclusion of a sentence-final particle in one given tonal category or other: tone, if present at all, seems hopelessly tangled with intonation. Despite this methodological difficulty, it now appears well-established that there exist different situations across languages in this respect.

Do sentence-final particles have lexical tones?

A first-level question concerning sentence-final particles is whether they have tone at all.

Chinese languages (Sinitic languages) are extensively researched in this respect, as in many others. In Mandarin, sentence-final particles belong among toneless syllables (C. N. Li and Thompson, 1981, p. 238) -a set that also includes some other grammatical morphemes, and some final syllables within lexical disyllables. Cantonese does not have a parallel set of toneless syllables, and the status of sentence-final particles in Cantonese is less clear-cut than in Mandarin. The view that Cantonese sentence-final particles carry lexical tones is relatively widespread. However, descriptions that assign a lexical tone to Cantonese sentence-final particles only use a subset (three to five, depending on the analysis) of the six tones found on sonorant-final syllables, which constitutes evidence that Cantonese sentence-final particles are not fully integrated into the language's system of lexical tones. Cantonese sentence-final particles have been described as possessing segmental and tonal variants, e.g. je vs. jek [START_REF] Chan | Sentence particles je and jek in Cantonese and their distribution across gender and sentence types[END_REF]; [START_REF] Leung | A study of the Cantonese hearsay particle wo from a tonal perspective[END_REF] distinguishes two variants of wo (喎), wo3 vs. wo5, and Ding (2013) distinguishes three. Cantonese sentence-final particles possess an especially strong expressive dimension. There have even been attempts to dissect them into a dozen of sub-syllabic semantic units: "4 initials (l, z, l/n, m), 2 rhymes (aa and o), 3 tones (1, 4, 5), 1 coda (k) and 2 such elements incorporating a tone (g3 and aa4)" (Sybesma and B. Li, 2007). A phonetic comparison of Cantonese sentence-final particles with (near-)homophonous syllables in the same position within a carrier sentence (W. W. [START_REF] Li | Sentence-final particles in Hong Kong Cantonese: Are they tonal or intonational?[END_REF]Li, , p. 2293) ) concludes that sentence-final particles have lexical tone, in view of the fact that the f 0 curves over sentence-final particles and those of lexical words with the same (hypothesized) tone are "more similar than different". Chance similarity between the f 0 curves of a lexical tone and of an intonation pattern realized over a sentence-final particle cannot be ruled out, however, especially for a language with as many as six lexical tones. It may therefore well be the case that the pitch of Cantonese sentence-final particles only bears the most distant relations to lexical tones: that it is essentially intonational, and to be described along a continuum of degrees instead of in terms of lexical tonal categories. All in all, Cantonese sentence-final particles constitute a borderline case, neither clearly toneless (as in Mandarin), nor clearly aligning with the language's main tone system. By contrast, in Vietnamese, there is a consensus that final particles possess a lexical tone, which is phonetically affected (but not phonologically erased) by intonation. All of the six tones found in smooth syllables (syllables without a final stop) are found on sentence-final particles. From a phonetic/phonological point of view, Vietnamese sentence-final particles are also much closer to the language's other morphemes than they are in Cantonese.

Several studies have been conducted about the interaction between lexical tone and intonation of final particles in Vietnamese [START_REF] Ha | Modelling the interaction of intonation and lexical tone in Vietnamese[END_REF][START_REF] Brunelle | Intonation in Northern Vietnamese[END_REF]Mac et al., 2015). The intonational change in the tone of final particles occurs through a variation in the amplitude of the lexical tone curve (expansion, or conversely compression, of the lexical tone), and through a shift in register (up or down) (Brunelle, Hạ, and Grice, 2012, p. 4). These phenomena can be described within the framework of a superpositional model of prosody, in which tone and intonation are conceived as superimposed: local modulations (tones) are grafted onto a modulation that spans larger domains (intonational group, utterance).

The fact that the Vietnamese tone system incorporates phonation-type characteristics makes it easier to investigate whether sentence-final particles have a lexical tone. For tones that comprise medial or final glottalization, the systematic presence of these precise phonation-type characteristics provides strong evidence that the hypothesized (lexical) tone is present. Two examples are the particle ạ, which consistently has final glottal constriction, and the particle đã, which consistently has medial glottalization. 7Looking back on the above reflections, it seems that the research question whether sentence-final particles have a lexical tone or not leads to enter into language-specific issues that can be thorny (as in the case of Cantonese), without bringing out a clear general picture. A suggestion here is to stand back somewhat from these synchronic questions, by reformulating the research issue as: To what extent to sentence-final particles retain a consistent lexical tone through time? The latter question arguably helps arrive at insights into a range of languages of Southeast Asia.

Are the tones of sentence-final particles diachronically stable?

In some cases, where the question whether function words such as sentence-final particles have lexical tones of their own is hard to answer, it can be useful to look into their etymology. In cases where one is lucky to find good hypotheses on etymology, it is important to look into the regularity (or lack of such) of historical developments to the present-day form.

The etymology of many of the Vietnamese sentence-final particles is straightforward. Here are two examples. The sentence-final imperative đi /ɗi/ is derived from the verb 'to go', with which it is still homophonous. The morpheme đã /ɗa/, which in nonfinal position means 'already; past', acquires a modal/attitudinal meaning when used as a sentence-final particle: 'Let me sleep!' can be expressed as Hãy để tôi ngủ đi (exhoRtative + to let + 1sg + to sleep + impeRative), with final imperative sentence-final particle, or as the stronger Để tôi ngủ đã, where the sentence-final particle đã conveys an indication that the speaker's decision to go to sleep is not open to discussion anymore. The evolution is semantically unsurprising: the past, unlike the future, is the domain of fact and certainty, which explains how the past morpheme đã could give birth to a sentence-final particle that expresses a type of assertion precluding contradiction. Here, the origin of the grammaticalized morpheme is clear, and the lexical tone remains unchanged. But this case should not blind the observer to different configurations.

In various languages of the Austroasiatic, Tai-Kadai and Sino-Tibetan families, there are some function words that behave differently from content words in prosodic terms (and also in terms of vowels and consonants, but that topic will not be discussed here). These function words can be sentence-final particles, topic markers, adpositions and the like. Those function words that can be related to content words in which they diachronically originate have sometimes undergone tonal developments that do not follow the same rules as content words. This provides evidence that the prosodic properties of function words can go their own sweet way, cutting off ties to the lexical words in which they originate: sometimes losing their tone altogether, sometimes acquiring another tone. Not to mention sentence-final particles of expressive origin: the wealth of sentence-particles whose segmental composition is simply the vowel /a/ strongly suggests that those are of expressive origin.

It is against this general background that the Muong facts set out below are to be understood. It will be argued here8 that the situation is one where there is less clear association of lexical tones to sentence-final particles than there is in Vietnamese.

Tone and intonation on sentence-final particles in Muong

Table 5.1 shows particles observed in interrogative sentences in Muong. A detailed inventory of sentence-final particles in the language (aiming at comprehensiveness) remains to be established, as part of a reference grammar of Muong.

The first question raised about these sentence-final particles is whether the notion of boundary tones is relevant to describing their intonation.

Boundary tones or tone coalescence?

In many languages, interrogation is characterized by a rising melody or the raising of a final portion of the utterance, and the suppression of the declination line (Pike, 1948;[START_REF] Cristo | Intonation in French[END_REF]. Muong is no exception to this statistical trend, which is not a [START_REF] Rialland | Typological studies in word and sentence prosody[END_REF]: it can be seen from Table 5.1 that most of its interrogative markers bear an ascending contour. Statement 2 presents an example containing [ci], an interrogative marker that enters the composition of questions about 'what, which, which'. The tone diacritics on the final particles provide a stylization of their pitch curve: [˨˥] for the ascending curve of the syllables [ci˨˥] and[re˨˥ ] in Example 2 and 3, [˧˨] for the descending curve of the syllable [ci˧˨] in Example 3. This solution is chosen for the sake of clarity, in order to provide an indication of the prosodic realization of the particles without assigning a lexical tone to each one (which would involve an element of arbitrariness: see the warnings in Section 2.1.2). Figure 5.10 shows the phonetic realization of these two statements.

( In Example 2, the interrogative particle /ci/ shows a modulation: descending, then clearly ascending at the end. If we had to assign a lexical tone to this word, it would definitely be Tone 3, an ascending tone -even if we have to note that the rise observed in this example is of a magnitude which clearly exceeds that of an ordinary Tone 3. However, when we compare Example 2 with Example 3, it is clear that it would be mistaken to attribute the final rising contour of the statement to a rising lexical tone which the morpheme /ci/ would carry. Indeed, the addition of a second particle, /re/, which is placed after the interrogative particle /ci/, has the effect of shifting the rising tone towards this second particle. The word /ci/, on the other hand, is lowered, and its duration is clearly less than in Example 2. The same phenomenon is observed for four other particles in Table 5.1: /căŋ/, /cuə/, /nɔ/, /ʔăj/.

The phenomenon seems to us to lend itself to two rather divergent interpretations. One would be to consider that the final particles have no tone of their own, and that entities are freely expressed which we will describe, according to our theoretical preferences, as intonational morphemes (in the spirit of Delattre's or Rossi's reflections, mentioned in Section 2.1.1) or as boundary tones [START_REF] Liberman | The intonational system of English[END_REF][START_REF] Karlsson | Intonation adapts to lexical tone: the case of Kammu[END_REF]: intonational effects which are concentrated at the edge of the intonational domain (in particular, at the beginning and at the end of the utterance). From this perspective, in Example 2, an interrogative intoneme (or boundary tone) is found at the end of the utterance, where it manifests itself phonetically as a strong rise. In other words, it is the interrogative intonation that takes precedence here. The differences between Example 2 and Example 3 in the realization of the interrogative morpheme /ci/ (strongly rising in Example 2, falling in Example 3) would then be explained as a direct consequence of the fact that the same intonational event is A second way of looking at the facts would be to imagine that a tonal reassociation phenomenon takes place. The emphatic/deictic particle /re/ would be present underlyingly in Example 2, but reduced to the point where it leaves only its tone, which would be reassociated with the previous morpheme: the interrogative particle /ci/. According to this hypothesis, the descending-ascending contour on the morpheme /ci/ 'what' in Example 2 would result from the combination (a kind of amalgam) between the two morphemes /ci/ and /re/. Thus, Example 3 would manifest the full form of which Example 2 is a reduced version. In Example 3, the interrogative morpheme /ci/ would manifest its lexical tone, which would be a descending tone. The striking similarity between the terminal contours of the two statements, which suggests that they are phonologically identical, would reflect the identity of the underlying lexical tone sequences.

Such processes of tonal reassociation are not as common in East Asian languages as they are in the Sub-Saharan domain, but they are nevertheless attested there [START_REF] Hyman | Kuki-Thaadow: an African tone system in Southeast Asia[END_REF][START_REF] Michaud | Reassociated tones and coalescent syllables in Naxi (Tibeto-Burman)[END_REF][START_REF] Jacques | Introduction à la phonologie historique du chinois[END_REF][START_REF] Michaud | Tone in Yongning Na: lexical tones and morphotonology[END_REF]. Tonal reassociation during syllable reduction can be considered to belong to the field of tonal sandhi, understood in a broad sense (Chen, 2000, p. 25). This type of speech reduction is familiar to us from the example of Vietnamese. When the tempo of a conversation accelerates, it is common for final particles to "go away" and only their melody remains. For example, in Example 4, the final particle can be reduced, leaving only an ascending final contour, where we recognize the mark of its lexical tone, B1 (rising). PART.DEM 'What is that?'

The reduction of deictic particles becomes clear when comparing the North Vietnamese and South Vietnamese dialects. North Vietnamese uses disyllabic pronouns consisting of the pronoun proper followed by the deictic ấy: cô ấy /koA1 ʔɤjB1/ 'she', anh ấy /ʔɛŋ A1 ʔɤjB1/ 'he', bà ấy /ɓaA2 ʔɤjB1Ư/ 'she (informal)', and so on. South Vietnamese, on the other hand, tends to reduce these forms by retaining only the pronouns, but with a change in tone (shift to C2 tone). It seems reasonable to imagine that this evolution has been done because of the phonetic proximity between the pitch curve of the strongly coarticulated disyllable and that of the lexical C2 tone, which, in Southern Vietnamese, has a low-ascending contour.

These observations are proposed as hypotheses: it remains to be verified by psycholinguistic means to what extent the tone of monosyllabic pronouns is well identified with the lexical tone C2 'thanh hỏi'. At least the analysis seems plausible, from the point of view of the language system concerned, and also typologically. The fact that the reduced syllables are deictics is consistent with typological expectations about syllabic reduction.

To summarize, both hypotheses outlined above have their strengths. The second one seems to us more satisfactory insofar as it brings the intonation facts, which are notoriously difficult to analyze, back to the field of mechanisms that are familiar to us: coarticulation and syllabic reduction. However, the first hypothesis is not without utility in the perspective of a dynamic synchronicity (André Martinet, 1990) sensitive to the changes of which the current situation bears the seeds. Indeed, the final intonation of Examples 2 and 3 could break the ties with its segmental origins (assuming that these are confirmed). Rather than being drawn into the tonal system and entering a pre-existing lexical category (such as South Vietnamese pronouns, which are in the C2 tonal category), it could be perpetuated as an intoneme, or boundary tone, associated with interrogation.

One point that seems important for this discussion is that the state described in Table 5.1 has variants that seem quite distinct. Looking at the descending-ascending curve in Example 2, we are inclined to the second hypothesis, while the simple final rise that constitutes the other variant of the interrogative contours makes us more inclined to opt for the first hypothesis. This type of hesitation is typical of "on the edge" situations, which inform about the permeabilities that can exist between tonal and intonational systems. It is particularly important not to be locked into a model that excludes a priori the existence of such interactions. Just as in biology, well-established certainties have delayed the recognition of the existence of certain mechanisms of information transfer between cells [START_REF] Prochiantz | Can transcription factors function as cell-cell signalling molecules?[END_REF], so a phonological model that would compartmentalize tones and intonation in a watertight manner (or, conversely, represent them in an entirely homogeneous manner) would impede in-depth observation of the type of phenomena exemplified by Muong intonation.

The following paragraph is meant to be another touch on the subject. It deals with one of the most delicate points of intonation modeling: the question of intonation tones.

An intonational tone in Muong?

In the majority of cases, the interrogative intonation in Muong is realized by a strong rise on the last words of the sentence, especially on the final particles. Nevertheless, there is also another case (less frequent, but clearly and systematically attested) in which the question ends on a final particle realized with a descending f 0 .9 We refer again to Table 5.1 to see that the second particle, /wə/, and the eighth, /hɔ/, belong to this second type. We will focus here on the particle /hɔ/, used to ask for confirmation or agreement. This particle is used either at the end of a sentence or alone in response to a question, as illustrated in Example 5. The final particle /hɔ/ in Example 5 attracts attention in that it carries a pitch contour which is distinct from all the lexical tonal categories in the system. To the ear, its prosodic realization has a striking proximity to the glottalized Vietnamese B2 tone (the nặng tone of the Vietnamese orthography). They share a strong final glottal constriction. However, the Vietnamese B2 tone is, in its canonical realization, a descending tone, due to the fact that it starts from fundamental frequency values that are not low to begin with (Brunelle, D. D. Nguyên, and K. H. Nguyên, 2010), while the f 0 contour of the /hɔ/ particle is plain (flat), as illustrated in Figure 5.11.

If we look for the tone closest to (or rather, least distant from) this contour among the lexical tones of Muong, we must look for tones 1 to 5, which can appear on a syllable without a final occlusion, such as /hɔ/. Among these five tones, glottalization is only present in Tone 4. However, because of the descending-ascending modulation and the passage in creaky voice (phonation mechanism zero) that characterize it, Tone 4 presents a very different appearance from the "tone" of the final particle /hɔ/. Moreover, this "tone" only appears in two particles, both represented in Examples 5 and 6, one in the question (the particle /hɔ/, just mentioned), the other in the answer: the particle /kuə/, which, used alone, marks assent. It is therefore hardly possible to speak of an eighth tone of the system. In intuitive terms, it seems that a tonal niche has been created: a specific communicative function (marking strong assent) has availed itself of a phonetic-phonological pattern introduced through North Vietnamese (of which all Muong speakers are speakers to varying degrees): that of Vietnamese tone B2. It would seem that Muong speakers are no less sensitive than others (native speakers of European languages, e.g. French or German) to the auditory impression produced by the strong glottal constriction present in two of the tones of North Vietnamese, and that they have borrowed this pattern -that of a Vietnamese tone -to make an intoneme out of it (an "intonational tone"). In terms of communication, this intonational tone is all the more univocal as its use is restricted. Without venturing to predict its future fortune, in a context of gradual replacement of Muong by Vietnamese, it is conceivable that this intonational tone will come to be used on an increased number of morphemes, while retaining (at least initially) the semantics currently associated with it.

This delicate pattern appeared as an apt final flourish for the present chapter, as it highlights the fact that glottalization is not only a salient and interesting phenomenon in itself: it also opens up a potential for interaction with other characteristics of linguistic systems. This final paragraph thus illustrates how glottalization, woven together with intonation, links up with the broader topic of creativity -phenomena that arise in language contact (in this instance, Muong and Northern Vietnamese), and in speech communication generally.

Chapter 6

Conclusion and perspectives

… he had a private instinct that a proof once established is better left so.

Mark Twain, The Man That Corrupted

Hadleyburg, 1899, cited in [START_REF] Garellek | Toward open data policies in phonetics: What we can gain and how we can avoid pitfalls[END_REF] In the present study, experimental phonetic means were deployed to gain a better understanding of phonetic dimensions that are known to be important cues to linguistic tone in an East/Southeast Asian context: fundamental frequency, which has pitch as its perceptual counterpart, and glottal open quotient, a parameter that relates to phonation types. A special focus of this thesis consisted in taking up the challenge of studying in detail the phonation of a glottalized tone.

On a methodological note, the study confirms the usefulness and feasability of the use of electroglottography as part of the experimental setup in phonetic studies of tone in a fieldwork setting. Challenges such as the overall more noisy signals (lower signal-to-noise ratio) for female speakers did not prove insuperable in creating, in the field, a data set that holds up to professional standards in experimental phonetics.

An essential part of this final chapter is to provide a brief and clear recapitulation of the answers to the research questions formulated in the first chapter.

• Concerning the first question: "What is the role of the creaky voice in Kim Thuong Muong's tone system?" It can confidently be concluded that although creak is cross-linguistically associated with lower pitch, this does not have the power to 'predict' glottalization phenomena in Kim Thuong Muong in full phonetic detail.

The phasing of glottalization inside rhymes carrying Tone 4 does not result from low-level phonetic phenomena. The association of creaky voice to Kim Thuong

Muong Tone 4 can safely be interpreted as due to a phonological specification.

• Concerning the second question: "To what extent is there phonetic variation in the glottalized tone?" It has been demonstrated in this thesis that glottalization in Kim Thuong Muong Tone 4 has creaky voice as its canonical realization and glottal constriction as a variant. The sub-classification of types of creaky voice found in the implementation of this tone was initiated in this study by qualitative observations, with the help of a simple script, CreakDet. Bringing out the conditioning of the variants constitutes a program which I intend to carry out in future work. Looking back to take stock of the results, I am most aware of all that remains to be done. In particular: conducting state-of-the-art statistical analysis of the extracted parameters. The parameters extracted from the electroglottographic signal (f 0 dEGG and O q dEGG ) were only used here for descriptive statistics and visual display: in-depth statistical analysis remains to be carried out, teasing out the contribution of various parameters including (i) lexical tones, (ii) experimental conditions and (iii) speakers, of course, but also (iv) segmental contexts (intrinsic properties of vowels and co-intrinsic properties of initial consonants), which well deserve attention, not least due to their well-documented importance in tonogenetic processes. Thanks to the help of Solange Rossato (Laboratoire d'informatique de Grenoble, UMR 5712), some basic descriptive statistics are already in progress and will be made public in the upcoming work after this study.

Two obvious directions in which to supplement the present work would be to conduct perception studies, 1 and to relate audio and electroglottographic data to physiological observations and modeling. 2 These research directions constitute a captivating research program for the mid term.

There has nonetheless been some progress. The documentation of the Kim Thuong Muong tone system now reaches a stage where fundamental tonemic issues can be considered solved. Phonological and phonetic questions pertaining to tonation can be explored based on a reasonably rich and diversified corpus that contains vocabulary, narratives, conversations and songs in addition to phonetic/phonological experiments. Beyond the results reported in the present volume, this set of data holds potential for further studies in experimental phonetics, and may also prove a useful resource for other fields of linguistic research.

1 Work on the perception of tonal contrasts in Southeast Asia has developed over recent decades, partly thanks to digital technology facilitating signal processing and perception tests. Among specialists in this field, I am aware of the work of [START_REF] Burnham | The role of linguistic experience in the perception of Thai tones[END_REF], [START_REF] Svantesson | Tone production, tone perception and Kammu tonogenesis[END_REF], [START_REF] Abramson | Thai final stops: cross-language perception[END_REF] and [START_REF] Abramson | Voice register in Khmu: Experiments in production and perception[END_REF], [START_REF] Zsiga | Tone features, tone perception, and peak alignment in Thai[END_REF], [START_REF] Brunelle | Social effects on the perception of Vietnamese tones[END_REF], Brunelle (2009b), [START_REF] Brunelle | Northern and Southern Vietnamese tone coarticulation: A comparative case study[END_REF]Finkeldey (2011), Brunelle (2012), and [START_REF] Brunelle | Tone and phonation in Southeast Asian languages[END_REF], [START_REF] Kirby | Dialect experience in Vietnamese tone perception[END_REF] and Kirby (2014), and[START_REF] Gruber | An articulatory, acoustic, and auditory study of Burmese tone[END_REF]. The picture of village life in Vietnam looks widely different, raising important issues in terms of experimental design. It looks as if SpeechRecorder provided coverage for any language, since the tool offers "Unicode text to display most of the world's languages"1 and audio prompts can be used for languages that are unwritten. But interacting with a computer did not seem the right way to go for my data collection campaign, given the lack of prior familiarity of Muong consultants with computer interfaces. The consultants' understanding of the task, and their interpretation of the investigator's purposes and intentions, are of paramount importance to the data collection process, and deserve much attention. Exploratory work led to adoption of a custom, 'handcrafted' protocol, which is somewhat at variance with procedures that are currently standard in many laboratory settings, but which I believe is true in spirit to the essentials of scientific research.

A.1.1 Learning from an earlier pilot study: difficulties of operating at a phonemic level

To arrive at perfect symmetry of a corpus, which is highly desirable for the systematic study of individual parameters and their interplay, it is tempting to bypass the com-plexities of the lexicon of the target language: to study phonological factors on their own. The use of pseudo-words (sometimes called logatoms) allows the investigator to focus on phoneme-level phenomena, building higher-level phonological units from the inventory of phonemes in the target language. A list of items is generated by exploring phonotactic combinations in a systematic way. This device is widely used in studies of Vietnamese [START_REF] Earle | An acoustic phonetic study of Northern Vietnamese tones[END_REF][START_REF] Gsell | Remarques sur la structure de l'espace tonal en vietnamien du sud (parler de Saıgon)[END_REF]Michaud, 2004b) as well as in other languages (for English: [START_REF] Dollaghan | Constituent syllable effects in a nonsense-word repetition task[END_REF]Michael S. Vitevitch et al. 1997b;[START_REF] Goswami | Children's orthographic representations and linguistic transparency: Nonsense word reading in English, French, and Spanish[END_REF]Hay, Drager, and Thomas 2013a). However, the use of forms not directly related to a meaning (that of a lexical item) raises difficulties in an unwritten language because there is no way to illustrate phonemic combinations to the consultants without building some sort of transcription system, adapting the writing system of another language, with the risk of phonological interferences. In the case of Muong, the obvious choice is the writing system with which the speakers are familiar through schooling, namely Vietnamese writing. This involves a number of potential pitfalls. The Muong people share with other communities of speakers of unwritten languages the characteristic that they (overall) speak their language with very little awareness of its phonemic system. On the other hand, the schooling that they receive in Vietnamese includes grapho-phonemic drills in Vietnamese spelling -a writing system which encapsulates various peculiarities that date back to pioneer 17th-century work by European linguists with Romance backgrounds (André-Georges Haudricourt, 2010). Therefore, code-switching between the sound systems of Muong and Vietnamese, and perhaps blending both in various proportions, are extremely difficult to avoid when using for Muong a Vietnamese-based phonemic transcription system.

Here as elsewhere in this study, the approach taken is an empirical one: if non-words allow for a successful investigation, then I am happy to use them. But a pilot study reported in my M.A. thesis (M.-C. Nguyên, 2016, p. 22) with syllables some of which do not constitute real morphemes (words) led to the clear conclusion that this method was not applicable given the fieldwork settings. This pilot study seems worth recapitulating here in extenso in order to shed full light on this important topic.

The experiment using non-words (i.e., designed as a phonemic exercise) was referred to in the M.A. thesis as "Experiment 2". It was designed as a supplement to "Experiment 1", which was based on real words: recording two minimal sets built on the basis of the word list available at the time. In order to gain insights into intrinsic and co-intrinsic effects on fundamental frequency (coarticulatory effects of rhymes and initials on f 0 ), it seemed worth trying out whether a reading experiment could yield interesting results despite the obvious difficulties associated with conducting a reading task in an unwritten language.

In term of vowels, I selected maximally different vowels, therefore choosing /i/, /a/ and /u/: a high front vowel, /i/; a low vowel, /a/; and a high back (rounded) vowel, /u/. As for consonants, unvoiced stops appeared as a convenient set for ease of segmentation, so I selected three unvoiced plosives: /p/, /t/ and /k/ (note that Muong, unlike Vietnamese, has /p/ in vocabulary of Vietic stock). It appeared interesting to have two series at similar places of articulation, allowing for a comparison of nasals An important issue when preparing the stimuli was the order in which tones are recorded. Explanations about tones are not the easiest part when using written stimuli, because the proposed system has to be learned entirely: to avoid interferences with Vietnamese, the orthographic representations used for Vietnamese tones are not used for Kim Thuong Muong; the tone symbols chosen are numbers, a convention which does not exist in many writing systems, and which is not used in Vietnamese, the system with which the speakers are already familiar. Given the difficulty of cueing a tone, it seemed simpler at first to divide the data into seven sets, arranging them by tone: eliciting all the syllables that have Tone 1, then all those that have Tone 2, and so on. This is easier for the consultants, as they keep tone constant while the syllable's initial and rhyme change. However, a drawback of this procedure is that the consultants' attention is drawn to the segments (consonants and vowels), which change from one syllable to the next, and are thus in focus, whereas tone is constant from one syllable to the next within each of the 7 tonal sets. Tone can therefore tend to become less and less clearly articulated, because the ordering of items makes it a less contrastive phonological component of the syllable. Since the focus of the research was on tone, what was wanted was 'canonical' distinction: the fullest realization of the tonal templates. So it seemed advisable to change tone systematically from one token to the next. This solution was implemented in the final set of recordings. Tones were cued by displaying a pane with four images for each tone illustrating words that bear this tone: see An obvious drawback is that the consultant's experience of reading and writing is intimately linked with their practice of the Vietnamese language. It is possible to give consultants some training in a writing system adapted from Vietnamese to Muong, and to give them the instruction to speak in Muong and not in Vietnamese. But despite my best efforts, under this setup, 'classroom' behavior surfaced at various points: getting back into the groove of the sound system of Vietnamese. As mentioned above, all consultants had received training in Vietnamese writing through primary schooling, whereas none had received training in Muong writing: neither at school nor later.

The obstacle was found to be insuperable. The sound systems of Vietnamese and Muong simply could not be efficiently kept apart. The failure of the non-words experiment in my master study led to the choice made here to use only attested words. Later in chapters of result and discussion, this topic will be taken up again, contrasting the present study's complete results with my previous work. To preview the results, they confirm that there is a gaping difference between the "read" materials of "Experiment 2" and those elicited later by means of more ecologically valid methods: those classically employed in fieldwork on unwritten languages, to which we return in the next section.

Trying to summarize in a few word what is specific about phonetic data collection in an immersion fieldwork context, I would highlight two points. First, for the sake of data homogeneity, one has to exert constant attention to ensure that the consultants are comfortable and focused. Second, it is advisable to cast the net wide and record more types of speech data than is strictly necessary for the specific research goal at hand, as it is likely to be difficult (costly in funding, time and effort) to gather additional data from the same speakers later as the necessity for it arises. Thus, in this study, the focus is on the characteristics, interactions, and variety in the realizations of a phonologically glottalized lexical tone. The more spontaneous and natural the speech, the more challenging it is for the experimenter to tease out the influence of various factors, so my first focus was on sets of words that minimally contrast for tone (recording words in isolation and in a carrier sentence). But the ultimate goal is to understand how acts of communication work in the real-world diversity of contexts, so I also recorded narratives, conversations and other data which, in phoneticians' typology, fall into the wide category of "spontaneous speech". Even though exploitation of the latter part of the data set has barely begun, it provided a useful point of reference from the start, and I consult it regularly over the months and years. Thinking early and often about possible hypotheses for later work allowed me to look beyond carefully controlled materials, to more complex data, like someone studying human gait who processes laboratory data on walking but likes to observe the complex patterns of various styles of dancing, and to think of connections. Researchers working on the world's top 5% best-documented and most widely spoken languages (as a rule of thumb: about 300 languages, including, as a matter of course, most national languages) can do this easily, by serendipitous observation of data that are not part of their experimental data set: language is everywhere. But when working on a newly-documented language variety, as is the case here, one has to record data by oneself.

The discussion which follows bears on the reasons for choosing specific types of materials, the selection strategies, their advantages and drawbacks, and ways to overcome some limitations, as well as the method that was found to be applicable for Kim Thuong Muong. It is hoped that some of these reflections also hold for other unwritten languages, striking a hopeful note for phonetic experiments in the field.

A.2 Strategy for finding (near-) minimal sets in an unwritten language

On the basis of the experiment involving real words designed in 2016, the strategy going forward was clear: extending the same experiment by finding additional minimal sets, and selecting pictures (photos) as stimuli for the data collection task. To be more specific, the process of finding (near-) minimal sets and pairs can be described in terms of the four following steps.

Step 1: Vocabulary collection. This is an indispensible prerequisite for finding (near-) minimal sets. Thanks to the EFEO-CNRS-SOAS word list which was designed for conducting in-depth lexical investigation when doing fieldwork on languages of Southeast Asia, we enjoy the benefits of a good tool to collect a good amount of basic vocabulary of Kim Thuong Muong. Due to time constraints in 2016 (when carrying out fieldwork as part of the master's degree), only 600 items from this word list were recorded. This amount of vocabulary was already sufficient to find a couple of tonal minimal sets. One of the goals of the current study was to extend the list of minimal sets and to add minimal pairs consisting of checked syllables. The more vocabulary we have, the more possibilities there are to find such sets (not to mention the obvious usefulness of a well-groomed word list, with the ultimate aim of publishing a full-fledged dictionary). Therefore, during this doctoral project, I availed myself of the additional field trips and favourable conditions for scientific work to elicit the full list: about 2,900 words. An enriched basis was thus available for tasks such as the search for (near-) minimal sets and pairs.

Step 2: Transcription in IPA. It is highly recommended to make the transcription in International Phonetic Alphabet immediately during the recording sessions. Thus we can easily check with the consultant(s) and make sure that every phonemic transcription is correct. If, for any reason, it cannot be done during the recording, it should at least be done during the field trip, rather than taking untranscribed recordings back to the laboratory. It certainly makes for a more reliable workflow, and it saves time and effort because verifications are much easier during fieldwork than later. In fieldwork we are always surrounded by locals who can help us verify. For instance, during the recording session of the vocabulary collection, I ran into a difficulty in perceiving the differences between two level tones (Tone 1 and Tone 5), in contexts where they are co-articulated with other tones: in particular, in compound words. Therefore, I usually had to double-check with the consultant by asking her to repeat the word several times slower, saying the two syllables of the compound word separately.

The word list that I used for this step is available online in Open Office format (.ods) and MS-Excel format. I worked in the Excel file, for no better reason than because that was the format I had used from the start, in the framework of the DO-RE-MI-FA project which aimed to digitize the audio recording collections of Michel Ferlus, many of which rely on this word list.

The search for tonal minimal sets was much facilitated by the work previously carried out on the language's phonological system. The essentials of the system of phonemes and tones had been worked out since my 2016 study. The background tasks of continuing vocabulary collection and double-checking transcriptions for accuracy and consistency went smoothly, and did not bring up any significant changes to the analyses produced at the time.

Step 3: The separation of phonemic components. After recording the entire word list and inputting them into the Excel file, the next step is to separate and classify each minimum phonemic component of each word into columns, in terms of: initial consonant, glide, vowel, final consonant, tone. This step serves at least three purposes.

• Firstly, we can easily examine the phonemic system from various angles, such as: listing the vowels (mono-vowels or diphthongs), the consonants, the position(s) they can occur in, and their possible combinations. • Secondly, we can consider systematically (by the function of sorting and filtering on Excel) any uncertain contrasts and double-check to make sure whether they are distinct phonemes, allophonic variations, or just free variations. In this study, an outstanding puzzle was whether there exists a distinction between the alveolar trill /r/ and the alveolar tap/ flap /ɾ/, or between the alveolar fricative /z/ and the palatal fricative /ʝ/. By gathering all the puzzling words and applying the method just mentioned, we have identified them as free variations, not distinct morphemes. • Thirdly, using the same Excel function of sorting and filtering, one may be lucky to find some minimal sets already nice and complete. Obviously, that depends on the amount of collected vocabulary. Otherwise, it is at least possible to find tonal minimal pairs or incomplete minimal sets. This is the material for the last step.

Step 4: Supplementing incomplete sets by searching for missing words. A complete minimal set for this study contains 5 words that distinguish 5 tones (on a smooth syllable). As a starting-point towards this goal, we searched and picked incomplete sets that have at least three target words (out of the desired total of five). It would be possible to start from a minimal pair (2/5) or even from a single word (1/5) and search for new items to supplement it, but that is highly impractical. Forcibly searching for lexical items containing a desired combination of segments and tones is tedious. It threatens to feel like a never-ending and disorienting work for consultants.

First, I prepared the incomplete sets in advance: listing them in order to know which tones are already available and which tones are missing in the set. The ideal setup for this step is that there are at least two native consultants who can help at the same time, supporting each other in the task of examining and supplementing the minimal sets. In this study, I took advantage of the fact that I was staying in a local family. I asked for help from a family member. A small financial reward was associated with participation in the task, which helped clarifying that the task was to be taken seriously. In addition, I asked other members of the family to come around to give extra help. and Michaud, 2015). On the other hand, a drawback of this method is that the speakers might be distracted by a memory task. As mentioned in the section of the word lists (3.1.1), some words are more abstract than others, for which a direct illustration cannot be found. Therefore, these words must be explained in detail to the speaker at the training stage and required to memorize their implication. This may compete with the requirements of good phonetic realization: it is expected that consultants will be able to focus on a clear phonetic realization of the tone. However, if some items are more difficult to remember than others, a sudden recall after a moment of hesitation (which may be awkward or stressful for the speakers) may be accompanied by a different phonetic realization. This is not to say, of course, that the task is beyond the speakers' abilities. Indeed, this experiment was carried out without great challenges with all speakers at different ages, levels of education, occupations, etc. Still, it seems that they would be more confident (and thus more consistent in their realization of the tones) if they were guided carefully through the list, item by item. And during the recording, whenever they encounter problems with hesitation or mispronunciation, they are asked, and given the freedom to re-produce them. This is clarified at the beginning to reduce participants' anxiety about making mistakes.

The selection of photos required some care so as to cue the intended monosyllable unambiguously. The choice was made in consultation with Muong speakers; this also offered an opportunity to familiarize them with the experimental procedure. Illustrative photos are selected based on certain criteria. Ideally, they were taken locally, so that participants can easily acquaint themselves with the subjects or activities, especially in case they are local concepts. Figure A.4 provides examples of photos taken in the field (by myself). However, when the number of illustrative photos is relatively numerous (here is 66 items), the actual photography is not the optimal way because they take a lot of time to search for objects in surrounding or setting the scene that is not always available. For this reason, in most cases, we searched and chose photos from the Internet,2 as long as they meet the criteria of being as direct and clear as possible. In other words, if the photo illustrates a noun, the thing should be the main subject on a plain background (white or black). If the photo illustrates a verb (an action), perhaps the context is important, then we try to avoid the presence of people, especially the faces of people to prevent it from stealing the attention of the speaker. If it was unavoidable, then the people and the surroundings should be similar to the local ones, especially avoid using images of foreign people and sceneries. Otherwise, minimalist sketch is also an option to avoid distracting scenes as much as possible. For example, the illustrative photos for target words /kɔ³/ "to speak" in minimal sets N o 6 and /ŋa⁵/ "to fall" in minimal sets N o 9 are using this method (as reproduced in The case of adjectives will be more difficult because they are more abstract than other types of lexical words in nature. They are used to describe the characteristics of a thing or activity, which means that there is no other way to illustrate them directly but to borrow the image of the object possessing those properties. Being aware of this disadvantage, we have kept the use of adjectives in our word list to a minimum. Only four of the sixty-six target syllables could be recognized as adjectives, which is:

1. Minimal sets N o 2: /rɔ¹/ in ʔɤ⁵ rɔ¹ "idle" 2. Minimal sets N o 2: /rɔ²/ "to be sated" 3. Minimal sets N o 10: /ka¹/ "big" 4. Minimal sets N o 11: /kaj⁴/ "female" We can easily notice that the illustrations of these four adjectives all bear a somewhat indirect relationship to the intended word, reflecting the difficulty of finding a context, action, or state that is exactly spot-on: so relevant that it allows for immediate identification, and so easy for speakers to remember that the experiment flows smooth as silk. The photos A.6a and A.6b do not directly illustrate /rɔ¹/ "idle" and /rɔ²/ "to be sated". We must employ a specific example of "idle", which is a moto-taxi driver resting on his motorcycle because there are no customers, and the context implying "to be sated" is someone with a conspicuously full stomach in front of empty dishes. In the photos A.6c and A.6d, in order to evoke the words "big" and "female", subjects exemplifying these characteristics are placed in a comparative opposition. Some might find fault with the use of foreign persons and contexts in illustrative photos for /(ʔɤ⁵) rɔ²/ "to be sated" (A.6b) and /ka¹/ " big" (A.6c), as also in two other cases: /paj⁵ (tʰăj¹)/ "arm span" and /ʔɤ¹ (kiɛŋ³)/ " beside". But to me it is clear that such a criticism would miss the key point: participants understand and accept the principle to prioritize the selection of an image that is closest to the content that is being illustrated, rather than other principles such as homogeneity in terms of the cultural contexts from which the for experimenters to handle data collection by themselves if there is no assistant to help showing the photos (an assistance that I was fortunate to have for my M.A.). It saves a lot of preparation time and are more eco-friendly because there is no need to print, cut and arrange the photo cards in order. Once the photos have been placed in the slides, they are already well-organized, with exactly the same order and quantity, no risk of messing up or losing them.

A further advantage is that the display of minimal sets will be much easier and more efficient to visualize in a slideshow. As can be seen in the demo slideshow showing illustrative photos for the elicitation of the first minimal sets (Figure . 3.5, the minimal set is started by an empty slide with only the number of its order of appearance, as a signal announcing the beginning of a particular set. The next slide shows five photos together to help the speaker recognize the expected minimal set. After that, the photos are presented one by one to draw attention to each particular element when the speaker has to utter them within the carrier sentence.

• (Figure B.1e): a pro-audio XLR Male -XLR Female cable for connecting mic outputs to the recorder. • (Figure B.1f): an adapter converting a 6.3mm stereo jack socket plug to a 3.5mm stereo jack for connecting the recorder to a headphone in order to listen the recording directly during the session. In fact, the Roland recorder can operate with 2 types of power: AC adapter and AA batteries. However, since the electric network is not grounded in the village, if using the AC adapter for power, there will conductive metal in contact with the speaker's skin during he/she wears the head-worn microphone. If the voltage differential between the two threads is not 220V vs. zero, but, say, 320V vs. 100V, there is a 100-V difference with the ground, which results in current down into the earth through the consultant's body. An internet search about electric shocks due to non-grounded microphones yields a harvest of horror stories about strong electric shock, with real threats to the consultants' peace of mind during recording and even to their health. This is a serious issue in the case of audio recording. The same problem was also reported by Alexis Michaud during his fieldwork in remote areas of Yunnan. A good solution would have consisted in asking an electrician to provide grounding for the entire household, thus improving the family's security, in addition to solving the issue encountered in fieldwork. But no electrician was available locally to perform the operation. Given this situation, it appeared safest to rely on batteries instead, conducting all recordings on alkaline batteries. With four alkaline batteries each, the Roland recorder can operate in about an hour. Therefore, to record at least 20 people for the experiment and also for the vocabulary collection task, I estimated and brought 80 batteries to the field. That is a huge number of batteries. The fact is that the batteries after the recording can still be used for other devices for a while. I gave them to local people who want to recharge their clocks, lamps, toys, etc. However, I later regretted realizing that they will be discarded in the environment since there is no local system for the treatment of electronic waste yet. This is to say, the batteries may be a safety solution to help overcome electrical problems when using a recording device, but its potential problems of damaging the local environment must also be taken into account consciously.

B.1.2 Electroglottographic device

Electroglottography, an important exploratory technique for the present study, is presented in Section 2.4 below. In the present paragraph, I just say a few words about practical issues concerning the choice of an electroglottographic device, and its use as a part of the experimental setup that I took to the field.

There are several electroglottographic devices on the market. The one made available to me was a Glottal Enterprise EG2-PCX 4 Beside the main device -the electroglottograph proper: a 2-channel electroglottograph -, the manufacturer also provides supporting components (Figure B.2) as mentioned on their website (here). Among them, what we really needed, and brought to the field, includes:

• (G) 35mm dual channel electrodes • (E) Power supply • (I) Tube of Electrogel • EG2-PCX2 Manual This equipment is connected to the Roland recorder via an XLR (male) -minijack cable as shown in Figure B.2b, so that the output, i.e. the EGG signal, can be recorded simultaneously with the acoustic signals. The EGG signal cannot be checked (by eye) directly during recording, but it can be listened to through a channel on the Roland recorder where it is set by the user. In my case, for the current study, I placed it in the third channel.

In addition, there are features in the equipment that allow us to control and know the quality of the signal in a rough way. The first one is the larynx position indicator as in Figure B.3c. This indicator is useful when the researcher attaches two electrodes to the speaker's neck. This signal can be consulted to know when the electrodes are placed in the right position as the LEDs is quite stable in green. Otherwise, if the LEDs move too far to the left or right into the yellow zone or worse into the red zone, it means that the electrodes are placed too high or too low, and still need to be adjusted.

The second feature -calibrateable LED signal strength indicator (as Figure B.3d), can be used to verify that the waveform is strong enough to reliably indicate vocal fold contact area variation. In general, men's signals are stable and good at 8 to 10 points. The women's signal is usually not as good, usually at 5 to 8 points, and many only at 2 to 3 points. The result of such weak signal is mostly difficult or impossible to analyze. These are the cases that were archived but not processed as indicated in the Table 3.7 as "No analysis" because of "Weak EGG signal".

Unlike the Roland recorder, this EGG equipment is equipped with six rechargeable batteries inside, so it can be recharged by the power supply before the recording session. This is convenient because it will not encounter the problems of electrical shock, machine noise, electronic waste or recording interruption due to battery change, etc. However, one experience to note is that when transporting this equipment through customs in the case of moving from abroad (as in my case, from France to Vietnam), be sure to keep in mind that if the equipment is put in carry-on luggage to keep it secure, we should always bring the user manual with it, as customs officers may want to check the battery information to see if it's safe to bring it on board. I ran into this problem in 2019, they were about to delay my flight and prevent me from taking this equipment on board because I could not provide the battery information. It took me a while to show them the website and explain the function of the equipment. 1. Name of audio files. The file name already contains four pieces of information: (i) the language code: the identifier of each document begins with <crdo-> (the former name of the platform hosting the Pangloss Collection) followed by the ISO code of the language in the Ethnologue catalogue of languages (the code for Mường is MTQ), followed by a short dialect identifier in capital letters, i.e., KTM;

(ii) the code of the speaker who recorded these audio files: "F" for Female and "M" for Male, followed by a number (from 1 to 21) referring to the order in which the consultants participated in the research (detailed information about the consultants is provided in Table 3.3); (iii) the basic content of the recording and (iv) an indication about successive repetitions of recordings with similar contents: "1" for the first run and "2" for the second run (remember that some experimental routines were run twice). Underscores are used as separators between pieces of information. and explain why we selected those colors. The developments that follow inevitably require previewing some of the results to be set out later in this dissertation, as the choice of colors is linked to phonetic/phonological properties of the tone. The selected colors are based on two criteria: (i) giving an impression that is compatible with the intended tone, and (ii) setting a good contrast for optimal observation. On the first criterion, in order to help the reader get familiar with the tone system, we attempt to apply the method of tone→color perception. Hereafter, every time each tone is mentioned, it will be highlighted with its associated color1 , as in Table C.1.

C.1.0.1 Tone and color perception

The study of the synesthesia of sound and colors is a fascinating topic. The first time I was exposed to this strand of research was in the spectrogram reading course of professor Jacqueline Vaissière (at École doctorale 622, Sorbonne Nouvelle). Figure C.1 is the piece of that course where she explains why and how each vowel can be represented by a certain color, according to her perception.

Indeed, there are many interesting findings about the relationship between sounds and colors. For instance, several studies on vowel-color mapping find that lighter colors (yellow, green) tend to be associated with more front vowels (higher F2; e.g., /i/, /e/), darker colors (e.g., red, brown, blue) with back vowels (/o/, /u/) [START_REF] Wrembel | On hearing colours-Cross-modal associations in vowel perception in a non-synaesthetic population[END_REF][START_REF] Marks | The unity of the senses: Interrelations among the modalities[END_REF]. These findings echo psychophonetic intuitions by Fónagy about front vowels being closer to the lips, and hence to the light of day, whereas back vowels are deeper inside the vocal tract, as it were, and hence steeped in darkness [START_REF] Fónagy | La vive voix: essais de psycho-phonétique[END_REF]. Now coming to pitch, a robust pattern seems to be the association of brighter colors with higher pitch, and darker colors with lower pitch [START_REF] Marks | The unity of the senses: Interrelations among the modalities[END_REF]. A cross-linguistic overview is provided by [START_REF] Anikin | Implicit associations between individual properties of color and sound[END_REF]: see in particular their Table 1, pp. 3-4. Here, following the idea of sound-color synesthesia, we try to associate each tone with an appropriate color, used systematically in the figures showing results for f 0 dEGG and O q dEGG . Specifically: Tone 1 is associated with green color because I get a sense of nature when listening this tone. The flat contour presumably gives a feeling of stability, lightness, and tranquility. It is somewhat like a soft breath: if it were wind, it would be like a breeze. The other level tone of the system, Tone 5, is the highest in pitch, giving a sensation of something bright, clear, cheerful and soaring. The color of a vivid clean sky was assigned for this tone: cyan. Blue is the color I see when listening to Tone 2 because its sharp fall makes me perceive something forceful, strong, and quick like waves in a choppy sea, or the image of dolphins rushing away and diving quickly into the water. In contrast, the movement of Tone 3 is somewhat lighter and less intense. It reminds me of the rising movement of the sun at dawn. Not that the rise is slow and sluggish: it is also fast, but somehow calm, gentle and serene. Therefore, a light orange is used as the color for representing this tone. Last but not least, the glottalized tone, labeled as Tone 4, is associated with red, the color of lava stone. We think it is an excellent match for this tone, since the glottalization has creaky voice as its most frequent phonetic realization, bringing the perception of something solid, rough, and at the same time pretty light, like volcanic stones (full of bubbles of air -reminiscent of the impression that, in creaky voice, bubbles are escaping between the adducted vocal folds). Additionally, there are also two tones in checked syllables, which are classified as a sub-system within the tone system, distinct from the sub-type of 5 tones in smooth syllables. These two tones were included in the experiment for the sake of completeness, but they are not an important object of study in the present dissertation. Therefore, they are both backgrounded, using shades of grey to set them apart as a separate sub-type. Tone 6 is represented by brighter grey in comparison with the shade used for Tone 7, reflecting in visual terms their distinguishing characteristic in term of pitch level: Tone 6 is higher than Tone 7.

The explanation in Table C.1 is a brief summary that will be useful to help remember the basic distinguishing impressions associated with the various tones, which may be all the more helpful as there is no accompanying sound. good color contrast simply involves choosing colors that differ clearly from one another. Crisp contrast adds visual clarity and appeal. On the other hand, contrast should be applied in a balanced way, especially in a complex combination: too much contrast can do more harm than good (somewhat like excessive use of spice in cooking), by creating a confusing or visually jarring appearance. The colors chosen in the previous step were therefore subjected to inspection from the point of view of their combinatorial properties as colors for display on the same graphs, fine-tuning them for better contrasts according to basic principles based on hue and lightness (tint and shade). A color wheel is a visual representation of the relationships of color hues. Two colors that sit opposite each other on the color wheel are called complementary colors. These colors create highest contrast to each other at maximum saturation. However, this stark contrast can make them visually jarring. Besides, we can also have analogous combinations in which 2 to 5 (ideally 2 to 3) colors are adjacent to each other on the color wheel. In comparison with complementary combination, the contrast between analogous colors is admittedly lower, but it tends to create a calming, likeable impression (as I learnt from a "color combination cheat sheet"). A color wheel is a good way to help us think about how different hues relate to one another. It can serve as a practical way to determine whether a pair (or more) of colors will relate to one another in a harmonious way.

3. 2

 2 An effort to illustrate abstract nouns . . . . . . . . . . . . . . . . . . . . . . 3.3 Informed consent form (Page 1) . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Attestation of payment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 A demo slideshow showing illustrative photos for the elicitation of the first minimal sets. This is accompanied by an explanation inTable 3.4. . 3.6 Basic procedure of data processing. . . . . . . . . . . . . . . . . . . . . . . . 3.7 Segmentation principle: examples of different treatments for voiced and unvoiced initial consonants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8 Segmentation principle: minimum span of three cycles in token 6512 (syllable /ja²/), data from speaker F3. . . . . . . . . . . . . . . . . . . . . . 3.9 Segmentation principle: treatment of missing syllables/rhymes . . . . . . . 3.10 Segmentation principle: treatment of the initial voiceless consonant which becomes a voiced consonant under coarticulation and hypoarticulation. . 3.11 Mono electroglottographic .wav file: the second input of PeaKDet . . 3.12 Regions List: the second input of PeaKDet. . . . . . . . . . . . . . . . . . 3.13 A schematic representation of data processing with PeaKDet. . . . . . . 3.14 Two ways to open and run PeaKDet on MATLAB: (i) (in red): PeaKDet is opened in CuRRent FoldeR Window and executed by typing "peakdet_inter" in the Command Window; (ii) (in magenta): PeaKDet is opened in the EditoR Window and executed by selecting Editor > Run from the toolbar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.15 The two dialog boxes that appear after calling PeaKDet, to request the location of the two input files. . . . . . . . . . . . . . . . . . . . . . . . . .

  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.19 Two operations for f 0 dEGG verification. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation. . 3.20 Example of a token where the first option (type 0) of the f 0 dEGG modification should be applied. Data from speaker M1, token: 03, UID: 0111, syllable /ja²/ (first frame word). . . . . . . . . . . . . . . . . . . . . . x 3.21 Example of a token where the second option (enter 1) of the f 0 dEGG modification should be applied. Data from speaker F21, token UID: 0501, syllable /paj⁴/. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 3.22 Example of a token where the third option (enter 2) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 2001, target syllable /laj⁴/ in isolation, first performance. . . . . . . . . . . . . . 127 3.23 Example of a token where the fourth option (enter 3) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 3502, syllable /kiɛŋ⁴/ in isolation, second performance. . . . . . . . . . . . . . . . 130 3.24 Example of a token where the sixth option (enter 5) of the f 0 dEGG modification should be applied. Data from speaker M14, token: 10, UID: 0142, syllable /ʈăŋ³/ the fourth word of carrier sentence, second performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 3.25 Former display (in the 2016 version) of O q dEGG calculated in four different ways: (i) maxima on unsmoothed dEGG signal (in green), (ii) maxima on smoothed dEGG signal (in blue), (iii) barycentre of peak on unsmoothed dEGG signal (in red), (iv) barycentre of peak on smoothed dEGG signal (in black). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 3.26 An example of O q dEGG curves with large differences across methods as a result of imprecise opening peaks. Reproduced from M.-C. Nguyên (2016): data of speaker M1, experiment 2, item 1331. . . . . . . . . . . . . . . . . . 138 3.27 An important tip when processing with PeaKDet: use two screens for a convenient view and time-saving operation. . . . . . . . . . . . . . . . . . 138 3.28 An example of item with imprecise opening peaks. Reproduction of (M.-C. Nguyên, 2016): item carrying UID 1331, speaker M1, experiment 2. Abscissa: in samples (1 sample = 1/44,100 second). . . . . . . . . . . . . 139 3.29 Some specific cases where selecting the method of the barycenter of the peaks on the smoothed signal (typing 3) is highly recommended. . . . . 141 3.30 Actions in the Command Window for the step of O q dEGG verification 143 3.31 Calculation of the total corpus . . . . . . . . . . . . . . . . . . . . . . . . . . 147 3.32 A brief summary view of the corpus . . . . . . . . . . . . . . . . . . . . . . 147 4.1 The tone system of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right. . . . . . . . . . . . . . . . . . . . . . . . 154 4.2 The tone system of Kim Thuong Muong: normalization across speakers. f 0 dEGG on the left and O q dEGG on the right. . . . . . . . . . . . . . . . . . 165 4.3 The Kim Thuong Muong's tone system: smooth tones (left) and checked tones (right), normalized on 20 speakers. . . . . . . . . . . . . . . . . . . . 166 4.4 The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right. . . . . . . . . . . . . . . . . . . . . . 172 xi List of Tables 2.1 Correspondences between Vietnamese and Muong for twelve body part names, adapted from André-Georges Haudricourt (1953). . . . . . . . . . . 2.2 Inventory of initial consonants . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Final consonants inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Palatal final consonants c and ɲ in inherited vocabulary and in loan words 2.5 Vowel inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 A brief overview of the tone system of Kim Thuong Muong. St.V. = Standard (Hanoi) Vietnamese. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7 Examples of a merger of etymological categories A2 and C2 in Kim Thuong Muong . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 Correspondences between Kim Thuong Muong -Vietnamese -Khmu, illustrating the presence of a final glottal stop in Palaung-Wa corresponding to tone B (B1 'sắc', B2 'nặng' in Vietnamese; and B1 -glottalized tone in Kim Thuong Muong.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1 Speech materials: eight minimal sets and four near-minimal sets that contrast for five tones in smooth syllables. . . . . . . . . . . . . . . . . . . 3.2 Speech materials: three minimal pairs that contrast the two tones of checked syllables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 A complete list of speakers / consultants who participated in the recordings from 2016-2019. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 An explanation of how the slideshow of illustrative photos is employed at training and when performing the experiment. . . . . . . . . . . . . . . 3.5 Annotation scheme: four digits. Structure: AABC, detailed below. . . . . 3.6 PeaKDet output information: .mat file containing a 10×100 matrix . . . 3.7 Current status of corpus: 20/28 data files have been annotated with Sound FoRgeand processed with MATLAB. . . . . . . . . . . . . . . . . .4.1 Some general information about the speakers' data: The values of the mean and standard variation of f 0 dEGG and O q dEGG and the ratio of the excluded O q dEGG values obtained by the quantitative analysis of the electroglottographic signal on twenty speakers. . . . . . . . . . . . . . . . . 5.1 Ten final particles involved in interrogative statements in Muong. . . . . C.1 List of representative colors for tones accompanied by a brief explanation of reasons for the choice of colors . . . . . . . . . . . . . . . . . . . . . . . xv Chapter 1

Figure 2

 2 Figure 2.1: A highly schematic representation of the components of prosody. Reproduced from Michaud (2017), with a minor change: replacing the original term "Lexically distinctive properties" by "Lexical prosodic properties".

FundamentalFigure 2 Figure 2 . 4 :Figure 2 . 5 :

 22425 Figure 2.3: Vietnamese tone A2 (huyền), as realized in isolation over the syllable /kɤ/ by a speaker from Hanoi. Year of recording: 1900.

FundamentalFigure 2 Figure 2 . 7 :

 227 Figure 2.6: Vietnamese tone C1 (hỏi), as realized in isolation over the syllable /kɤ/ by a speaker from Hanoi. Year of recording: 1900.

  Illustration of mistaken values at f 0 extraction during glottalization. Voicing threshold set at 0.7 in Praat. Illustration of mistaken values at f 0 extraction during glottalization. Voicing threshold set at 0.8 in Praat.

Figure 2 . 8 :

 28 Figure 2.8: Vietnamese tone C2 (ngã), as realized in isolation over the syllable /ɓa/ by a speaker from Hanoi. Year of recording: 1900.

Figure 2 .

 2 Figure 2.10: Acoustic patterns of six laryngealized types. Reproduced from Batliner et al. (1993).

Type 1 . 4 .

 14 Glottalized tokens illustrating aperiodicity. Type 2. Glottalized tokens illustrating creak. Type 3. Glottalized tokens illustrating diplophonia.Type Glottalized tokens illustrating glottal squeak.

Figure 2 .

 2 Figure 2.11: Acoustic patterns of four glottalized tokens illustrating different sub-types. Angled brackets above each waveform indicate the region where each subtype appears. Reproduced from Redi and Shattuck-Hufnagel (2001, pp. 415-416).

  (a) Waveform showing six kinds of creak. (b)

Figure 2 .

 2 Figure 2.13: Nomenclature systems of creak sub-classification provided by previous studies.

Figure 2 .

 2 Figure 2.16: Map of Vietic languages by Ferlus (1998).

Figure 2 .

 2 Figure 2.17: Map of Vietic dialects by V.-T. Nguyen (2005).

Figure 2 .

 2 Figure 2.18: Map of Kim Thuong Muong location in Phu Tho province, the dialect in red (http://bando.tnmtphutho.gov.vn/map.phtml).

Figure 2 .

 2 Figure 2.19: Tone box of Kim Thuong Muong

2 :

 2 Speech materials: three minimal pairs that contrast the two tones of checked syllables.

  Figure 3.2: An effort to illustrate abstract nouns

1

  Figure 3.3: Informed consent form (Page 1)

  (a) Slide 1: The start of the minimal set is displayed by a blank page with the digit of its order in the list, i.e. number 1 for the first minimal set. (b) Slide 2: Full set of 5 photos in one slide.

Figure 3 . 5 :

 35 Figure 3.5: A demo slideshow showing illustrative photos for the elicitation of the firstminimal sets. This is accompanied by an explanation in Table3.4.

Figure 3 . 5 :

 35 Figure 3.5: A demo slideshow showing illustrative photos for the elicitation of the first minimal sets. This is accompanied by an explanation in Table 3.4.

  Turn off mobile 'phones • Unplug the electroglottograph from the power grid • Put electrogel on the two electrodes of the electroglottograph • Place the electrode collar on the participant's neck • Take a picture of the speaker with full gear • Turn on the electroglottograph • Check the signals, using earphones • Start recording (Turn on the recorder) At the end of the session: • Turn off the electroglottograph • Stop the recording (Turn off the recorder) • Take off the electrode collar and head-worn microphone • Take a picture of the speaker's throat: the slight marks made by the electrodes' edges indicate their exact location • Wipe the electrodes • Turn on mobile 'phones again

Figure 3

 3 Figure 3.6: Basic procedure of data processing.

Figure 3

 3 Figure 3.7: Segmentation principle: examples of different treatments for voiced and unvoiced initial consonants.

Figure 3

 3 Figure 3.8: Segmentation principle: minimum span of three cycles in token 6512 (syllable /ja²/), data from speaker F3.

Figure 3

 3 Figure 3.9: Segmentation principle: treatment of missing syllables/rhymes

  (a) Usual treatment on the voiceless initial consonant on the syllable /ʈăŋ³/, data from speaker F13, UID 5844: the entire syllable is taken.(b) When the voiceless consonant becomes voiced on the same syllable /ʈăŋ³/ (the same speaker, F13, but another token, UID 5441): only the rhyme is taken.

Figure 3 .

 3 Figure 3.10: Segmentation principle: treatment of the initial voiceless consonant which becomes a voiced consonant under coarticulation and hypoarticulation.

  Figure 3.12: Regions List: the second input of PeaKDet. 108

Figure 3 .

 3 Figure 3.13: A schematic representation of data processing with PeaKDet.

Figure 3 .

 3 Figure 3.14: Two ways to open and run PeaKDet on MATLAB: (i) (in red): PeaKDet is opened in CuRRent FoldeR Window and executed by typing "peakdet_inter" in the Command Window; (ii) (in magenta): PeaKDet is opened in the EditoR Window and executed by selecting Editor > Run from the toolbar.

  Figure 3.15: The two dialog boxes that appear after calling PeaKDet, to request the location of the two input files.

  (a) The 2016 version: The display requesting selections for using three parameters. Reproduced from M.-C. Nguyên (2016). (b) The 2019 version (version 1.0.5): The parameters are set as default and displayed for the user to notice.

Figure 3 .

 3 Figure 3.16: The difference between two versions (2016 and 2019) of the initial settings in the Command Window after executing PeaKDet.

  (exemplified in Figure 3.17a): the curves of two parameters f 0 dEGG and O q dEGG automatically calculated by PeaKDet; • Figure 2 (exemplified in Figure 3.17b): the EGG signal; • Figure 3 (exemplified in Figure 3.17c): the first derivative of the EGG signal, also called dEGG signal; • Figure 4 (exemplified in Figure 3.17d): the second derivative of EGG signal or

  max, blue: barycentre. Boxes: smoothed dEGG, stars: unsmoothed. Figure1of PeaKDet display: Two parameters automatically calculated by PeaKDet: f 0 dEGG (in green) and O q dEGG ( in blue and orange).

  Figure3.17: A demo of four initial plots after automatic processing of a token by PeaKDet. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation.

  Two closing peaks are not detected at the 18 th cycle by the automatic Peakdet. the EGG (after smoothing). Red bars: detected closures. parameters after resetting the threshold at 0.001 to catch two undetected closing peaks.

  (a) First action: look at f 0 dEGG curve (green) in Figure4to check if there are any unusual values.(b) Second action: zoom in on the dEGG signal in order to verify closing peaks.

Figure 3 .

 3 Figure 3.19: Two operations for f 0 dEGG verification. The example is taken from the data of speaker M1, first token 0101, target syllable /paj⁵/ in isolation.

  (a) dEGG signals. An example of good and clear signal with all well-defined closing and open peaks.(b) Two parameters automatically calculated by Peakdet: f 0 dEGG (green) and O q dEGG (blue and orange).

Figure 3 .

 3 Figure 3.20: Example of a token where the first option (type 0) of the f 0 dEGG modification should be applied. Data from speaker M1, token: 03, UID: 0111, syllable /ja²/ (first frame word).

Figure 3 .

 3 Figure 3.21: Example of a token where the second option (enter 1) of the f 0 dEGG modification should be applied. Data from speaker F21, token UID: 0501, syllable /paj⁴/.

Figure 3 .

 3 Figure 3.21: Example of a token where the second option (enter 1) of the f 0 dEGG modification should be applied. Data from speaker F21, token UID: 0501, syllable /paj⁴/.

Figure 3 .

 3 Figure 3.22: Example of a token where the third option (enter 2) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 2001, target syllable /laj⁴/ in isolation, first performance.

Figure 3 .

 3 Figure 3.22: Example of a token where the third option (enter 2) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 2001, target syllable /laj⁴/ in isolation, first performance.

Figure 3 .

 3 Figure 3.22: Example of a token where the third option (enter 2) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 2001, target syllable /laj⁴/ in isolation, first performance.

Figure 3 .

 3 Figure 3.23: Example of a token where the fourth option (enter 3) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 3502, syllable /kiɛŋ⁴/ in isolation, second performance.

Figure 3 .

 3 Figure 3.23: Example of a token where the fourth option (enter 3) of the f 0 dEGG modification should be applied. Data from speaker M14, token UID: 3502, syllable /kiɛŋ⁴/ in isolation, second performance.

  .24c, and the corresponding result after correction is shown in Figures 3.24d and 3.24e. (e) EGG signal. After merging cycles 15 and 16. (f) dEGG signal. After merging cycles 15 and 16.(g) Result of f 0 dEGG (green) and O q dEGG (blue and orange).

Figure 3 .

 3 Figure 3.23: Example of a token where the fourth option (enter 3) of the f 0 dEGG modification should be applied. Data from speaker M14, token: 339, UID: 3502, syllable /kiɛŋ⁴/ in isolation, second performance.

Figure 3 .

 3 Figure 3.24: Example of a token where the sixth option (enter 5) of the f 0 dEGG modification should be applied. Data from speaker M14, token: 10, UID: 0142, syllable /ʈăŋ³/ the fourth word of carrier sentence, second performance.

Figure 3 .

 3 Figure 3.24: Example of a token where the sixth option (enter 5) of the f 0 dEGG modification should be applied. Data from speaker M14, token: 10, UID: 0142, syllable /ʈăŋ³/ the fourth word of carrier sentence, second performance.

  (d) dEGG signal. The three extra final peaks detected were excluded.(e) Result of f 0 dEGG (green) and O q dEGG (blue and orange). PeaKDet re-calculate these two parameters after the three extra final peaks detected were excluded.

Figure 3 .

 3 Figure 3.24: Example of a token where the sixth option (enter 5) of the f 0 dEGG modification should be applied. Data from speaker M14, token: 10, UID: 0142, syllable /ʈăŋ³/ the fourth word of carrier sentence, second performance.

Figure 3 .

 3 Figure 3.25: Former display (in the 2016 version) of O q dEGG calculated in four different ways: (i) maxima on unsmoothed dEGG signal (in green), (ii) maxima on smoothed dEGG signal (in blue), (iii) barycentre of peak on unsmoothed dEGG signal (in red), (iv) barycentre of peak on smoothed dEGG signal (in black).

  Figure 3.26: An example of O q dEGG curves with large differences across methods as a result of imprecise opening peaks. Reproduced from M.-C. Nguyên (2016): data of speaker M1, experiment 2, item 1331.

Figure 3 .

 3 Figure 3.27: An important tip when processing with PeaKDet: use two screens for a convenient view and time-saving operation.

  (a) Case #1: the top of the peak is divided into two small peaks that are really close to each other.(b) Case #2: similar to case #1 with the top of the peak are split but more severe.

Figure 3 .

 3 Figure 3.29: Some specific cases where selecting the method of the barycenter of the peaks on the smoothed signal (typing 3) is highly recommended.

Figure 3 .

 3 Figure 3.29: Some specific cases where selecting the method of the barycenter of the peaks on the smoothed signal (typing 3) is highly recommended.

Figure 3 .

 3 Figure 3.30: Actions in the Command Window for the step of O q dEGG verification

Figure 4 .

 4 4); (ii) a comparison on the distribution (Figure D.2) and the correlation (Figure D.

Figure 3 .

 3 Figure 3.31: Calculation of the total corpus

  Muong tone system: Speaker F7. Time in seconds. (120 syllables in total: 24 items for each tone) Muong tone system: Speaker F7. Time in seconds.(120 syllables in total: 24 items for each tone) Muong tone system: Speaker F9. Time in seconds. (120 syllables in total: 24 items for each tone) Muong tone system: Speaker F9. Time in seconds.(120 syllables in total: 24 items for each tone)

Figure 4 . 1 :

 41 Figure 4.1: The tone system of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 1 :

 41 Figure 4.1: The tone system of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 1 :

 41 Figure 4.1: The tone system of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 1 :

 41 Figure 4.1: The tone system of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 1 :

 41 Figure 4.1: The tone system of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

  Muong tone system: normalization of 10 female speakers. Time in seconds. (240 items for each tone) Muong tone system: normalization of 10 female speakers. Time in seconds.(240 items for each tone) Muong tone system: normalization of 10 male speakers. Time in seconds. (240 items for each tone) Muong tone system: normalization of 10 male speakers. Time in seconds.(240 items for each tone)

Figure 4 . 2 :Figure 4 . 3 :

 4243 Figure 4.2: The tone system of Kim Thuong Muong: normalization across speakers.f 0 dEGG on the left and O q dEGG on the right.

Tone 4

 4 stands out by a curve that is unmistakeably, obviously apart from that of all the other tones (F3 (4.1a), F7 (4.1b), F9 (4.1c), F10 (4.1d), F12 (4.1e), F17 (4.1g), F19 (4.1h), F20 (4.1i), F21 (4.1j), M1 (4.1k), M8 (4.1n), M9 (4.1o), M10 (4.1p) and M11 (4.1q)).

Figure 4 . 4 :

 44 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 4 :

 44 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 4 :

 44 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 4 :

 44 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 4 :

 44 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 4 :Figure 4 . 4 :Figure 4 . 4 :Figure 4 . 4 :

 44444444 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

Figure 4 . 4 :

 44 Figure 4.4: The glottalized tone of Kim Thuong Muong: speaker by speaker. f 0 dEGG on the left and O q dEGG on the right.

  whole data set. Two of the six typical examples of sub-types of creaky voice in Tone 4, shown in Figures 5.1 and 5.1, are from his data. Speaker M12 (4.4r) is noted as a special case where the first half of Tone 4 appears unusual with extremely high values, highly implausible for a male voice, above 400 Hz. This is reflected in the box plot (D.2) in Appendix D with the most numerous and highest outliers above 200 up to 500 Hz to be found in this speaker's data. The cause of this anomaly comes from double closing peaks with an early closing micro-peak that occurs at the beginning of each cycle (as shown in Figure 4.5) resulting in detection errors. This particular characteristic of M12 is clearly due to the fact that this speaker has glottalization in Tone 4: the detection errors frequently occur in this tone. As can be seen in Figures 4.1r and D.1r, the amplitude of the standard deviation at the beginning of Tone 4 is large and irregular and spans at least five half tones for one side. While the other tones do not show these erratic fluctuations.

  (a) EGG signal with a zoom on cycles 9 to 19 where the micro-closing peaks appear. (b) dEGG signal with a zoom on cycles 9 to 19 where the micro-closing peaks appear.(c) Result of f 0 dEGG (green) and O q dEGG (blue and orange).

Figure 4 . 5 :

 45 Figure 4.5: An example illustrates the unusual beginning of speaker M12's Tone 4 with unreasonably high f 0 dEGG values caused by micro-closing peaks. Data from speaker M12, token UID: 2002, target syllable /laj⁴/ in isolation, second performance.

  (a) Signals. From top to bottom: (i) acoustics, (ii) EGG, (iii) dEGG (b) Two parameters automatically calculated by PeaKDet: f 0 dEGG (green) and O q dEGG(blue and orange).

Figure 5 . 1 :

 51 Figure 5.1: Example of single-pulsed creak: extreme case. Data from speaker M11, token: 41, UID: 0501, over syllable /paj⁴/ in isolation. DOI: https://doi.org/10.24397/pangloss-0006782#W9

Figure 5 . 1 :

 51 Figure 5.1: Example of single-pulsed creak: common case. Data from speaker M11, token: 47, UID: 0531, over syllable /paj⁴/ in carrier sentence. DOI: https://doi.org/10.24397/pangloss-0006782#W10

  (a) Signals. From top to bottom: (i) acoustic signal, (ii) EGG, (iii) dEGG.(b) Two parameters estimated by PeaKDet: f 0 dEGG (green) and O q dEGG (blue and orange).

Figure 5 . 1 :

 51 Figure 5.1: Example of multiply-pulsed creak. Data from speaker F10, token: 551, UID: 6002, over syllable /ku⁴/ in isolation. DOI: https://doi.org/10.24397/pangloss-0006784#W224

  (a) Signals. From top to bottom: (i) acoustic signal, (ii) EGG, (iii) dEGG. (b) Two parameters automatically calculated by PeaKDet: f 0 dEGG (green) and O q dEGG(blue and orange).

Figure 5 . 1 :

 51 Figure 5.1: Example of jitter in harshness, illustrating a technical difficulty in automatic detection of multiply-pulsed creak. Data from speaker F12, token: 178, UID: 1832, over syllable /laj²/ in carrier sentence. DOI: https://doi.org/10.24397/pangloss-0006790#W170

  (a) Signals. From top to bottom: (i) acoustic signal, (ii) EGG, (iii) dEGG. (b) Two parameters automatically calculated by PeaKDet: f 0 dEGG (green) and O q dEGG(blue and orange).

Figure 5 . 1 :

 51 Figure 5.1: Example of aperiodic creak. Data from speaker F12, token: 541, UID: 5501, over syllable /kaj⁴/ in isolation DOI: https://doi.org/10.24397/pangloss-0006790#W109

  (b) Two closing peaks are not detected at the 18 th cycle by the automatic PeaKDet.

Figure 5 . 1 :

 51 Figure 5.1: Example of a maximum pressed voice. Data from speaker F21, token: 41, UID: 0501, over syllable /paj⁴/ in isolation. DOI: https://doi.org/10.24397/pangloss-0006812#W9

Figure 5 . 1 :

 51 Figure 5.1: Example of a maximum pressed voice. Data from speaker F21, token: 41, UID: 0501, over syllable /paj⁴/ in isolation. DOI: https://doi.org/10.24397/pangloss-0006812#W9 (cont.).

  All the examples are tokens of Kim Thuong Muong Tone 4. The reason why I chose to present two different examples for pressed voice here, instead of choosing the two examples from the online gallery (reproduced here as Figures 5.3 and 5.4), is that I find them more consensual: phoneticians are (a) Signals. From top to bottom: (i) acoustic signal, (ii) EGG, (iii) dEGG. (b) Two parameters automatically calculated by PeaKDet: f 0 dEGG (green) and O q dEGG(blue and orange).

Figure 5 . 2 :

 52 Figure 5.2: Example of a minimally pressed voice. Data from speaker F21, token: 42, UID: 0502, over syllable /paj⁴/ in isolation. DOI: https://doi.org/10.24397/pangloss-0006812#W141

Figure 5 .

 5 Figure 5.3: First example of pressed voice reproduced from the Github gallery of glottalized signals. 209

Figure 5 . 4 :

 54 Figure 5.4: Second example of pressed voice reproduced from the Github gallery of glottalized signals. 210

Figure 5 . 5 :

 55 Figure 5.5: Algorithm of CreakDet version 1

  tones over syllable /paj/. Tone 4 (UID 0501) is single-pulsed creak. (a) Minimal set containing the 'ideal' sample of single-pulsed creak in Fig. 5.1. DOI Tone 1: https://doi.org/10.24397/pangloss-0006782#W7 DOI Tone 2: https://doi.org/10.24397/pangloss-0006782#W5 DOI Tone 3: https://doi.org/10.24397/pangloss-0006782#W3 DOI Tone 4: https://doi.org/10.24397/pangloss-0006782#W9 DOI Tone 5: https://doi.org/10.24397/pangloss-0006782#W1 tones over syllable /paj/. Tone 4 (UID 0531) is single-pulsed creak. (b) Minimal set containing the 'normal' sample of single-pulsed creak in Fig. 5.1. DOI Tone 1: https://doi.org/10.24397/pangloss-0006782#W8 DOI Tone 2: https://doi.org/10.24397/pangloss-0006782#W6 DOI Tone 3: https://doi.org/10.24397/pangloss-0006782#W4 DOI Tone 4: https://doi.org/10.24397/pangloss-0006782#W10 DOI Tone 5: https://doi.org/10.24397/pangloss-0006782#W2

Figure 5 . 6 :

 56 Figure 5.6: Comparison of the smoo_deltaf 0 dEGG : an illustration for the consideration of the threshold established in condition 1 and 2.

  tones over syllable /ku/. Tone 4 (UID 6002) is multiply-pulsed creak. (c) Minimal set containing the sample of multiply-pulsed creak (in Fig. 5.1). DOI Tone 1: https://doi.org/10.24397/pangloss-0006784#W222 DOI Tone 2: https://doi.org/10.24397/pangloss-0006784#W220 DOI Tone 3: https://doi.org/10.24397/pangloss-0006784#W218 DOI Tone 4: https://doi.org/10.24397/pangloss-0006784#W224 DOI Tone 5: https://doi.org/10.24397/pangloss-0006784#W216 tones over syllable /kaj/. Tone 4 (UID 5501) is aperiodic creak. (d) Minimal set containing the sample of aperiodic creak (in Fig. 5.1). DOI Tone 1: https://doi.org/10.24397/pangloss-0006790#W107 DOI Tone 2: https://doi.org/10.24397/pangloss-0006790#W105 DOI Tone 3: https://doi.org/10.24397/pangloss-0006790#W103 DOI Tone 4: https://doi.org/10.24397/pangloss-0006790#W109 DOI Tone 5: https://doi.org/10.24397/pangloss-0006790#W101

Figure 5 . 6 :

 56 Figure 5.6: Comparison of the smoo_deltaf 0 dEGG : an illustration for the consideration of the threshold established in condition 1 and 2. (cont. 1)

Figure 5 . 6 :

 56 Figure 5.6: Comparison of the smoo_deltaf 0 dEGG : an illustration for the consideration of the threshold established in condition 1 and 2. (cont. 2)

Figure 5 . 7 :Figure 5 . 8 :

 5758 Figure 5.7: Illustration of how the "CRPdet.m" function works, through examples of (a) double-pulsed creak, (b) jitter, and (c) aperiodic creak. In each sub-figure, from top to bottom: (i) two variables: delta f 0 (in magenta and green) and smoo_delta f 0 (in blue and red) with EGG signal; (ii) f 0 dEGG ; (iii) acoustic signal; and (iv) dEGG.

Figure 5 . 8 :

 58 Figure 5.8: Overall results of CreakDet version 1.

  , 4.2 and 4.3, glottalization makes Tone 4 well-distinguished from the other four tones of smooth syllables. Glottalization sets apart Tone 4 by two acoustic properties. Firstly, fundamental frequency: Tone 4 is very different from the other tones, as its f 0 values usually drop from under 100 Hz to minimum values below 30 Hz whereas the four remaining tones are consistently inside a range between 100 and 150 Hz. Even without information of open quotient, Tone 4 can be identified as being the lowest tone, at the bottom of speaker's range, contrasting with the four remaining tones (which are distributed in the area from the middle to the top of speaker's range). Secondly, open quotient also tells apart Tone 4 from the others, with values of Tone 4 reaching below 30% whereas all the other tones have O q values above 40%.

Figure 5 .

 5 Figure 5.9: Figure of f 0 curves of Hanoi Vietnamese tones, reproduced from Kirby, 2011, p. 386.

FreqFigure 5 .

 5 Figure 5.10: Acoustic signal, spectrogramme and fundamental frequency plot of the examples 2 and 3.

( 4 )

 4

( 5 )Figure 5 .

 55 Figure 5.11: The final particle /hɔ/, taken from a dialogue prepared before recording.

Figure A. 1 :

 1 Figure A.1: Screenshot of the SpeechRecorder software from Vera Scholvin's doctoral study on "Prosody in French-Vietnamese Language Contact", with permission.

Figure A. 2 :

 2 Figure A.2: Experiment 2: Cards for target words. Yellow cards for smooth syllables and pink cards for stopped syllables.

  Figure A.3.

Figure A. 3 :

 3 Figure A.3: Experiment 2: Cards used in an attempt to cue tones.

  Figure A.5).

  Figure A.5: Two examples of illustrative photos that were picked by the method of minimalist sketch in order to avoid distracting scenes as much as possible.

  (hereafter EGG equipment), shown in Figure B.2.

  Figure B.1: Roland 4-channel recorder and its accompanying devices.

  Figure B.2: The Glottal enterprises EG2-PCX and its accompanying components.

Figure B. 4 :

 4 Figure B.4: The room on the ground floor of my Muong teacher's house was used as a "field recording studio" during all my field trips from 2016 to 2019.

Figure B. 5 :

 5 Figure B.5: The position of equipments on the recording (an illustration from the recording of speaker F5 in August 2015).

Figure C. 1 :

 1 Figure C.1: Color perception of French vowels. Reproduced (with permission) from the spectrogram reading course of Pr. Jacqueline Vaissière in 2018.

Figure C. 2 :

 2 Figure C.2: The distribution of representative colors of 5 tones on the color wheel.

  Figure D.1: Kim Thuong Muong's tone system presented in semitones: speaker by speaker. Same data as in Figure 4.1.

Table 2 .

 2 1: Correspondences between Vietnamese and Muong for twelve body part names, adapted from André-GeorgesHaudricourt (1953).

	numbering English	Vietnamese (IPA) Muong (IPA)
	1 2 3 4 5 6 7 8 9 10 11 12	head hair eyes ear nose mouth tooth tongue neck lip chin arm (or hand) tăj A1 ɗɤw A2 , ʈok D1 tɔk D1 măt D1 taj A1 muj B1 miəŋ B2 răŋ A1 lɯəj C2 ko C1 moj A1 kăm A2	ʈok tʰak măt tʰai mui mɛŋ not mentioned laːi kel, kok not mentioned kăŋ tʰai

Table 2 .

 2

			2: Inventory of initial consonants
		Labial Dental Alveolar Retroflex Palatal Velar Glottal
	Plosive	p pʰ	t tʰ	ʈ	k kʰ	ʔ
	Nasal	m	n	ɲ	ŋ
	Trill		r
	Fricative	β	s		ɣ	h
	Approximant	w		j
	Lateral
	Approximant		l
	Implosive	ɓ	ɗ

i e ɛ a ɯ ɤ u o ɔ/, three falling diphthongs /iə ɯə uə/, and two pairs of long and short vowels /ɤ-ɤ/ /a-ă/. As

	one goes into sub-phonemic detail, some
	interesting differences appear. For instance, Kim Thuong Muong has a falling diphthong

[iɛ], in complementary distribution with [ɛ]. The former appears before all final consonants other than the two palatals, /ɲ/ and /c/. Examples include: /tɛɲ⁴/ 'to fight', /tɛc⁷/ 'to put', as opposed to /riɛp⁷/ 'sandals', /kʰiɛt⁷/ 'lightning', /kiɛk⁷/ 'armpit', /kiɛm¹/ 'ice-cream', /tiɛn⁴/ 'narrow', and /tiɛŋ²/ 'nail'.

Table 2 .4: Palatal final consonants c and ɲ in inherited vocabulary and in loan words Num. Kim Thuong Muong Vietnamese English Note

 2

	/mɛɲ¹/ /tɛɲ¹/ /nwɛɲ²/ /kiɲ²/ /kɛɲ⁴/ /rɛɲ⁴/ /tʰɛɲ⁴/ /nɤɲ⁴/ /kac⁶/ /kʰac⁶/ /kac⁷/ /ke⁴ lac⁷/ /tɛc⁷ ɣuəŋ⁴/ /mic⁷/	nhanh, mau đan nhỏ, bé gần (nơi) cắn cái đó, lờ rắn snake (general) quick to weave small near to to bite fish basket nặn, vắt to squeeze cắt, chặt to cut sắt iron cát sand dây lạt bamboo strips đặt, để xuống put mật honey
	/sɛɲ¹/ /kiɲ¹/ /mɛɲ³/ /tɛɲ⁴/	xanh Kinh mạnh đánh (nhau)	green Vietnamese synonym: /taw⁴/ strong to fight
		Table 2.5: Vowel inventory
		i	ɯ	u
		e ɤ/ɤ̆o
		ɛ a/ă ɔ
		iɛ
		iə ɯə uə

Table 2 .

 2 6: A brief overview of the tone system of Kim Thuong Muong. St.V. = Standard (Hanoi) Vietnamese.

	tone	shorthand name label comparison with St.V.	etymology
	Tone 1 Mid-level Tone 2 Falling	[33]	lower than A1	C1

Table 2 .

 2 on this topic, he provided four examples to demonstrate that: tones of category B (in Vietnamese) come from a final glottal stop which are still preserved 7: Examples of a merger of etymological categories A2 and C2 in Kim Thuong Muong

	Muong Vietnamese	English	French
	/pɤj⁵/ /ɲa⁵/ /pun⁵/ bùn /ɓun A2 / trời /ʈɤj A2 / nhà /ɲa A2 / /waŋ⁵/ vàng /vaŋ A2 / gold sky house muddy /rɯŋ⁵/ rừng /rɯŋ A2 / forest /paw⁵/ bão /ɓaw C2 / typhoon /ŋɤŋ⁵/ ngỗng/ŋoŋ C2 / goose /muj⁵/ mũi /muj C2 / nose /tuə⁵/ đũa /ɗuə C2 / chopsticks baguettes ciel maison boueuse or forêt typhon oie nez /mɤ⁵/

mỡ /mɤ C2 / grease graisse in Palaung-Wa dialects and in Khmu. We reproduced his examples in Table 2.8 and added the correspondences in Kim Thuong Muong to confirm that Muong unmistakably follow this rule. Table 2.8: Correspondences between Kim Thuong Muong -Vietnamese -Khmu, illustrating the presence of a final glottal stop in Palaung-Wa corresponding to tone B (B1 'sắc', B2 'nặng' in Vietnamese; and B1 -glottalized tone in Kim Thuong Muong.) Palaung -Wa Vietnamese Muong Leaf /laʔ/ (Khmu), /laʔ/ (Riang) lá /la B1 / /la 4 / Fish /kaʔ/ (Khmu, Riang) cá /ka B1 / /ka 4 / Dog /soʔ/ (Khmu) chó /cɔ B1/ /cɔ 4 / Rice /rənkoʔ/ (Khmu), /koʔ/ (Riang) gạo /

ɣaw B2 / /kaw 4 /

  /laj/ in minimal set N o 4, 2. /taj/ in minimal set N o 5, 3. /kɔ/ in minimal set N o 6, 4.

/ma/ in minimal set N o 8, 5. /ŋa/ in minimal set N o 9, 6. /ka/ in minimal set N o 10, 7. /kaj/ in minimal set N o 11, 8. /ku/ in minimal set N o 12.

Table 3 .

 3 3: A complete list of speakers / consultants who participated in the recordings from 2016-2019.

	Note	2015: EGG signal was OK but	2018: getting crackling noise	Weak EGG signal	Good EGG signal	2Crakling noise	weak EGG signal	Weak EGG signal	Weak EGG signal	Speech ready gesture	Weak EGG signal.	A loud machine noise because	the volume has been turned up too high.	Strange EGG signal like F16.	Weak signal , up-and-down signal,	but creak is clear.	She make creak consitency with T4	(in continueous speech)	Good EGG signal	Weak EGG signal	Good EGG signal, good creak.	Very good EGG signal.	A talkative speaker.	Can sing.	She can sing folksongs	and tell folkore stories
	Rec.	years	2016	2018	2016	2016	2018	2016	2016	2016	2018	2018		2018			2018		2018	2018	2018		2018	2018
	Name Date of birth Address Gender	Sa Thị Đính 08.02.1983 Chiềng I female	Sa Thị Bích 15.02.1975 Chiềng I female	Sa Thị Đang 13.07.1984 Chiềng I female	Sa Thị Lình 14.12.1987 Chiềng I female	Trần Thị Thắm 10.12.1961 Chiềng I female	Phùng Thị Thanh 10.09.1956 Chiềng I female	Sa Thị Thảo 12.03.1988 Xóm Xuân 2 female		Sa Thị Hưu 06.08.1973 Chiềng I female			Hà Hồng Khanh 25.01.1991 Chiềng I female		Hà Thị Hòa 15.04.1973 Chiềng II female	Sa Thị Hoài 27.08.1982 Chiềng I female	Trần Thị Thảo 15.08.1972 Chiềng II female		Hà Thị Coi 16.05.1967 Chiềng I female	Hà Thị Xoan 20.08.1965 Chiềng I female
	ID	F1	F2	F3	F4	F5	F6	F7		F8			F9		F10	F11	F12		F13	F14
	N o	1	2	3	4	5	6	7		8			9		10	11	12		13	14

Table 3 .

 3 4: An explanation of how the slideshow of illustrative photos is employed at training and when performing the experiment.

	Slide -Display	Purpose	At training	At performance
	Slides 1: break slide (3.5a) A blank slide showing the order number of current minimal set	-Help speakers in the audio files to be aware of the beginning of a minimal set. -A sign for separation of minimal sets	They are informed the rehearsal of the purpose of this page and are instructed to read the number displayed on the page during	The speakers read the order number when the break page is displayed
		-Help speakers
	Slide 2: general slide (3.5b) Five photos are placed together	recognize the minimal set with five identical syllables but only different in tone. -In experiment, used for recording the minimal set	Walk the speaker through each photo and explain the target word expected	Speakers say the expected words in isolation, following the researcher's prompt: pointing to each photo in turn
		in isolation
		-Draw the
	Slides 3 -7: particular slides (3.5c, 3.5d, 3.5e, 3.5f, 3.5g) a particular photo Each slide presents	speaker's attention to each word the minimal set used for recording and ask them to say the word in the carrier sentence. -In experiment,	Let speakers remember the carrier sentence. the word in the expected word in each photo. Instruct them to practise saying	Speakers say the expected words in the carrier sentence
		in carrier sentence
	Slide 8: break slide (3.5h)	-Help speakers be aware of the switch to	They are informed of the purpose of this page
	A blank slide showing the order number of next minimal set	a new minimal set. -A sign for separation of minimal sets in the audio files	and are instructed to read the number displayed on the page during the rehearsal

Table 3 .

 3 5: Annotation scheme: four digits. Structure: AABC, detailed below. Item with UID 3611 means: the first syllable /ʝa2/ of carrier sentence in case /ma5/ is target syllable, first time. • Item with UID 6801 means: the check syllable /kap7/ in isolation, first time. • etc. We can also know the tone of the target syllable based on the number in position AA :

	Pos. Meaning	Number code
	AA	The UID of the target syllable, in two digits. Numbers from 1 to 9 are padded up with a zero.	01-40: words of 8 minimal sets 41-60: words of 4 near-minimal sets 61-66: words of 3 checked minimal pairs
		The nature of the annotated rhyme:	0: target syllable (in isolation)
		B = 0: target syllable said in isolation;	1: 1st syllable of frame -/ʝa2/
	B	1 ≤ B ≤ 4: token from carrier sentence. B indicates the order of the token	2: 2nd syllable of frame -/măt6/ 3: 3rd syllable of frame -target syllable
		inside carrier sentence,	(in carried sentence)
		3 means target syllable.	4: 4th syllable of frame -/ʈăŋ3/
	C	Repetition	1: first time, 2: second time
	• • Tone 1: 04 09 14 19 24 29 34 39 44 49 54 59; • Tone 2: 03 08 13 18 23 28 33 38 43 48 53 58; • Tone 3: 02 07 12 17 22 27 32 37 42 47 52 57; • Tone 4: 05 10 15 20 25 30 35 40 45 50 55 60; • Tone 5: 01 06 11 16 21 26 31 36 41 46 51 56; • Tone 6: 61 63 65; • Tone 7: 62 64 66;

Table 3 .

 3 6: PeaKDet output information: .mat file containing a 10×100 matrix

	Column	Value	Unit
	1st	the beginning of cycle	ms
	2nd	the end of cycle	ms
	3th	f0	Hz
	4th	DECPA: Derivative-Electroglottographic Closure Peak Amplitude
	5th	Oq determined from raw maximum without smoothing	%
	6th	DEOPA
	7th	Oq determined from maximum after smoothing	%
	8th	Oq determined from peak detection without smoothing	%
	9th	Oq determined from peak detection after smoothing	%
	10th

Table 3 .

 3 7: Current status of corpus: 20/28 data files have been annotated with Sound FoRgeand processed with MATLAB.

	N°Speaker Quality of EGG signal	Data status	Size of .mat file
	1 F1	Crackling noise	No annotation	No analysis

Table 4 .

 4 1: Some general information about the speakers' data: The values of the mean and standard variation of f 0 dEGG and O q dEGG and the ratio of the excluded O q dEGG values obtained by the quantitative analysis of the electroglottographic signal on twenty speakers.

	Speaker	Mean f dEGG (Hz)	Std f 0 dEGG	Mean O q dEGG (%)	Std O q dEGG	Ratio of excluded O q dEGG values (%)
	F3		35	59	9.9	25
	F7		35.6	65.5	7.8	25
	F9		48.8	52.5	10.8	36.3
	F10		37.4	56.2	9.7	26.2
	F12		43.4	52.4	8.8	12
	F13		53.3	52.2	8	12.3
	F17		40.6	45	9.7	14.5
	F19		29.8	56.4	11.5	21
	F20		46.1	57.5	13.7	88
	F21		41.7	61.1	8.8	7.42
	M1		26.6	44.5	11.8	17.3
	M5		32.3	52.9	8	8.7
	M7		25.6	48.9	9.1	6.9
	M8		21.3	51.5	7.6	24
	M9		37.7	58.2	10	4.7
	M10		19.5	49.1	10.9	17.4
	M11		24.9	49.4	9.8	13.4
	M12		47.9	54	6.4	23.3
	M13	90	15	55.4	8.6	31.4
	M14		24.7	54.8	6.3	23.5

  Kim Thuong Muong is closely related with Vietnamese from a diachronic point of view; moreover, Muong dialects have undergone wave after wave of influence from Vietnamese, strengthening similarities between these language varieties. Vietnamese dialectology, which is overall much more advanced than the study of Muong dialects, can serve as a source of inspiration for the study of Muong in general, and of Kim Thuong Muong in particular.For instance, it appears interesting to see to what extent glottalization in Kim Thuong MuongTone 4 resembles glottalization phenomena in Vietnamese dialects (and in other languages of the Vietic group). In Vietnamese, tone B2 (nặng) and C2 (ngã) are glottalized tones. In a comparison between Kim Thuong MuongTone 4 (based on the results of this study) and Vietnamese B2 and C2 (based on the results and figures of Kirby, 2011, reproduced here as Figure 5.9), 6 it can be confirmed that Kim Thuong MuongTone 4 differs from the glottalized tones of Vietnamese by at least the following characteristics:

Table 5 .

 5 1: Ten final particles involved in interrogative statements in Muong.

	Num.	Paticle in IPA	Modulation	Function	Vietnamese equivalent
		/căŋ/	high-ascending, an initial descent sometimes with	polar interrogative particle	không
		/wə/	high-descending, ends in breathy voice	polar interrogative particle concerning a situation in progress	à, hả
		/cuə/	high-ascending, sometimes with a final descent	polar interrogative particle: has the process started or not yet?	chưa
		/ci/	high-ascending, a final descent sometimes with	interrogative particle 'which'	gì
		/nɔ/	high-descending then ascending	interrogative particle 'where'	đâu
		/cɤ no/	/cɤ/ : high-flat, then rising /no/ : high-descending	interrogative particle 'when'	bao giờ
		/ʔăj/	high-descending then ascending	interrogative particle 'who'	ai
			low-flat,
		/hɔ/	stops on a glottal constriction	interrogative particle in confirmation questions: 'isn't it'.	nhỉ
			(glottic closure)
		/re/	high-ascending	final deictic particle of an curiosity, surprise, emphasis interrogative statement; expresses	thế, đấy
			low-flat,
	10	/kuə/	stops on a glottal constriction	particle indicating agreement with the interlocutor	phải, đúng
			(glottic closure)

  2. Date of recording. 3. Duration of the audio file.

	N°Name of WAV file N°Name of WAV file N°Name of WAV file N°Name of WAV file N°Name of WAV file	Date Date Date	Date Date	Duration Duration Duration Duration Duration
	216	crdo-MTQ_KTM_F1_COM-LAM crdo-MTQ_KTM_F1_MAKING-CAKE crdo-MTQ_KTM_F8F1_WELL crdo-MTQ_KTM_M12_LIFE crdo-MTQ_KTM_F14_FOLK-TALE_5 crdo-MTQ_KTM_F3_WORDLIST_P3	October 2, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:04:50 0:05:15 August 22, 0:51:04	0:02:13 0:02:54 0:02:55
	217	crdo-MTQ_KTM_F1_CHOI-HOI_1 crdo-MTQ_KTM_F1_CULTIVATE_2 91 crdo-MTQ_KTM_F8F1_A-WORKING-DAY crdo-MTQ_KTM_F12_MINIMALSET crdo-MTQ_KTM_F13_FOLK-TALE_VIE crdo-MTQ_KTM_F3_WORDLIST_P4	October 2, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:07:19 0:16:35 August 22, 1:02:05	0:03:14 0:01:31 0:04:20
	218	crdo-MTQ_KTM_F1_CHOI-HOI_2 crdo-MTQ_KTM_F1_BAMBOO-SHOOTS_4 92 crdo-MTQ_KTM_M9_MINIMALSET crdo-MTQ_KTM_F12_BANH-CHUNG_1 crdo-MTQ_KTM_F13F14_FOLKSONG_1 crdo-MTQ_KTM_F3_WORDLIST_P5	October 2, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:02:05 0:05:30 August 22, 0:24:56	0:03:47 0:13:53 0:07:21
	219	crdo-MTQ_KTM_F1_CULTIVATE_1 crdo-MTQ_KTM_F1_FOLK-GAMES 93 crdo-MTQ_KTM_M9_BANH-CHUNG crdo-MTQ_KTM_F12_BANH-CHUNG_2 crdo-MTQ_KTM_F13F14_FOLKSONG_2 crdo-MTQ_KTM_F3_WORDLIST_P6	October 2, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:02:49 0:05:25 August 22, 1:02:05	0:07:00 0:06:03 0:06:23
	220	crdo-MTQ_KTM_F1_BANH-CHUNG_1 crdo-MTQ_KTM_F1_HIV 94 crdo-MTQ_KTM_M9_FUNERAL crdo-MTQ_KTM_F12_A-WORKING-DAY crdo-MTQ_KTM_F14F13_FOLKSONG_3 crdo-MTQ_KTM_F3_WORDLIST_P7	October 2, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:04:50 0:01:49 August 22, 0:37:32	0:03:23 0:03:53 0:09:40
	221	crdo-MTQ_KTM_F1_BANH-CHUNG_2 crdo-MTQ_KTM_M1_MINIMALSET 95 crdo-MTQ_KTM_M9_WEDDING crdo-MTQ_KTM_F12_CULTIVATE crdo-MTQ_KTM_F14F13_FOLKSONG_4 crdo-MTQ_KTM_F21_MINIMALSET	October 2, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:14:23 0:05:03 August 22, 0:15:39	0:04:00 0:07:44 0:16:04
	222	crdo-MTQ_KTM_F1_FUNERAL-OF-UNCLE-TU_1 crdo-MTQ_KTM_M1F1_BANH-CHUNG October 26, 2018 October 2, 2018 96 crdo-MTQ_KTM_M9_ANT-SONG October 29, crdo-MTQ_KTM_F12_COM-LAM October 31, 2018 crdo-MTQ_KTM_M14_MINIMALSET November 2, 2018 0:03:15 0:01:52 crdo-MTQ_KTM_F21_BANH-CHUNG August 22, 0:01:50	0:08:33 0:00:51 0:19:05
	223	crdo-MTQ_KTM_F1_FUNERAL-OF-UNCLE-TU_2 crdo-MTQ_KTM_M1_LABOR October 26, 2018 October 2, 2018 97 crdo-MTQ_KTM_M9_FOLK-GAMES October 29, crdo-MTQ_KTM_F12_COOKING-FISH October 31, 2018 crdo-MTQ_KTM_M14_BANH-CHUNG November 2, 2018 0:01:50 0:00:45 crdo-MTQ_KTM_F21_A-WORKING-DAY August 22, 0:01:09	0:08:15 0:03:34 0:03:21
	224	crdo-MTQ_KTM_F6_WORKING-IN-FARM crdo-MTQ_KTM_M1_FISH 98 crdo-MTQ_KTM_M9_STUDYING crdo-MTQ_KTM_F12_FAMILY crdo-MTQ_KTM_M14_A-WORKING-DAY crdo-MTQ_KTM_F21_RICE-MILLING	October 16, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:01:32 0:04:56 August 22, 0:01:08	0:04:36 0:03:13 0:00:49
			crdo-MTQ_KTM_F6_MEDICINAL-PLANTS crdo-MTQ_KTM_M1_CULTIVATE 99 crdo-MTQ_KTM_M9_GIVING-BIRTH crdo-MTQ_KTM_F12_TET-HOLIDAY crdo-MTQ_KTM_M14_FAMILY	October 16, 2018 October 26, 2018 October 29, October 31, 2018 November 2, 2018 0:02:31 0:05:00	0:01:56 0:01:53 0:02:33
			crdo-MTQ_KTM_F6_FOLK-HEALING crdo-MTQ_KTM_M1_BAMBOO-SHOOTS 100 crdo-MTQ_KTM_M9_HERD crdo-MTQ_KTM_F13_MINIMALSET crdo-MTQ_KTM_M14_TET-HOLIDAY	October 16, 2018 October 26, 2018 October 29, November 1, 2018 November 2, 2018 0:04:33 0:19:37	0:01:31 0:01:37 0:01:10
			crdo-MTQ_KTM_F6_DEMONIC-POSSESSION crdo-MTQ_KTM_M1_TRAVELLING October 26, 2018 October 16, 2018 101 crdo-MTQ_KTM_F9_MINIMALSET October 30, crdo-MTQ_KTM_F13_BANH-CHUNG_1 November 1, 2018 crdo-MTQ_KTM_M14_LIVING-IN-FARM November 2, 2018 0:06:52 0:00:58	0:02:07 0:16:39 0:00:47
			crdo-MTQ_KTM_F6_FOLK-GAMES crdo-MTQ_KTM_M1_CHOI-HO 102 crdo-MTQ_KTM_F9_BANH-CHUNG crdo-MTQ_KTM_F13_BANH-CHUNG_2 crdo-MTQ_KTM_M12_MINIMALSET_2	October 16, 2018 October 26, 2018 October 30, November 1, 2018 August 15, 2019	0:02:50 0:04:35	0:02:11 0:05:38 0:23:28
			crdo-MTQ_KTM_F6_FAMILY crdo-MTQ_KTM_M1_FOLK-GAMES 103 crdo-MTQ_KTM_F9_SON crdo-MTQ_KTM_F13_LABOR-EXPORT crdo-MTQ_KTM_M12_BANH-CHUNG_2	October 16, 2018 October 26, 2018 October 30, November 1, 2018 August 15, 2019	0:04:03 0:12:31	0:04:00 0:04:48 0:04:10
			crdo-MTQ_KTM_F6_WEDDING crdo-MTQ_KTM_M1_FUNERAL 104 crdo-MTQ_KTM_M10_MINIMALSET crdo-MTQ_KTM_F13_A-WORKING-YEAR crdo-MTQ_KTM_F16_MINIMALSET	October 16, 2018 October 26, 2018 October 30, November 1, 2018 August 16, 2019	0:11:58 0:03:10	0:03:53 0:17:03 0:19:53
			crdo-MTQ_KTM_F6_ACCIDENTS crdo-MTQ_KTM_M7_MINIMALSET 105 crdo-MTQ_KTM_M10_BANH-CHUNG_1 crdo-MTQ_KTM_F13_FAMILY crdo-MTQ_KTM_F16_A-WORKING-YEAR	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:16:33 0:07:30	0:01:51 0:03:21 0:01:13
			crdo-MTQ_KTM_F6_FOLK-TALE_1 crdo-MTQ_KTM_M7F1_BANH-CHUNG 106 crdo-MTQ_KTM_M10_BANH-CHUNG_2 crdo-MTQ_KTM_F13_ANT-SONG crdo-MTQ_KTM_F16_BANH-CHUNG	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:04:36 0:00:12	0:02:43 0:07:41 0:02:28
			crdo-MTQ_KTM_F6_FOLK-TALE_2 crdo-MTQ_KTM_M7M1_CHILDHOOD 107 crdo-MTQ_KTM_M10_WORKING crdo-MTQ_KTM_F13_LULLABY_1 crdo-MTQ_KTM_F16_LULLABY	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:10:26 0:00:39	0:03:15 0:06:05 0:01:03
			crdo-MTQ_KTM_F6_FOLK-TALE_3 crdo-MTQ_KTM_M7F1_WORKING-IN-HANOI 108 crdo-MTQ_KTM_M10_FAMILY_1 crdo-MTQ_KTM_M13_MINIMALSET crdo-MTQ_KTM_F16_PRIVATE-LIFE	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:06:07 0:20:31	0:03:23 0:02:05 0:03:44
			crdo-MTQ_KTM_F6_FOLK-TALE_4 crdo-MTQ_KTM_M1M7_APPENDICITIS 109 crdo-MTQ_KTM_M10_MUONG-HOA-BINH crdo-MTQ_KTM_M13_BANH-CHUNG crdo-MTQ_KTM_F16_TET-HOLIDAY	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:06:24 0:05:34	0:02:54 0:04:23 0:01:28
			crdo-MTQ_KTM_F6_FISH crdo-MTQ_KTM_M7M1_FATHER 110 crdo-MTQ_KTM_M10_WORKING-DIFFICULTIES October 27, 2018 October 16, 2018 October 30, crdo-MTQ_KTM_M13_FAMILY November 1, 2018 crdo-MTQ_KTM_F17_MINIMALSET August 16, 2019	0:14:24 0:01:55	0:01:43 0:02:13 0:28:12
			crdo-MTQ_KTM_F6_SLAUGHTER crdo-MTQ_KTM_M1M7_ALCOHOL 111 crdo-MTQ_KTM_M10_TET2018 crdo-MTQ_KTM_M13_CULTIVATE crdo-MTQ_KTM_F17_BANH-CHUNG_1	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:06:47 0:01:37	0:02:07 0:02:34 0:02:01
			crdo-MTQ_KTM_F6_BASSINET crdo-MTQ_KTM_M1M7_FRIEND 112 crdo-MTQ_KTM_M10_FAMILY_2 crdo-MTQ_KTM_M13_ALCOHOL crdo-MTQ_KTM_F17_BANH-CHUNG_2	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:08:10 0:02:49	0:01:39 0:01:27 0:02:00
			crdo-MTQ_KTM_F6_NHA-SAN crdo-MTQ_KTM_M1M7_POLITICS 113 crdo-MTQ_KTM_M11_MINIMALSET crdo-MTQ_KTM_M13_WORKS-IN-FARM crdo-MTQ_KTM_F17_ANT-SONG	October 16, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:04:14 0:01:56	0:03:58 0:13:30 0:00:40
			crdo-MTQ_KTM_F1_MINIMALSET_1 crdo-MTQ_KTM_M1M7_CUSTOMS 114 crdo-MTQ_KTM_M11_BANH-CHUNG crdo-MTQ_KTM_M13_FOLK-GAMES crdo-MTQ_KTM_F17_PRIVATE-LIFE	October 23, 2018 October 27, 2018 October 30, November 1, 2018 August 16, 2019	0:09:47 0:02:38	0:10:55 0:03:35 0:02:00
			crdo-MTQ_KTM_F1_DOG_1 crdo-MTQ_KTM_M8_MINIMALSET 115 crdo-MTQ_KTM_M11_A-WORKING-DAY crdo-MTQ_KTM_M13_TET-HOLIDAY crdo-MTQ_KTM_F17_TET-HOLIDAY	October 23, 2018 October 28, 2018 October 30, November 1, 2018 August 16, 2019	0:21:52 0:03:01	0:02:36 0:00:52 0:01:13
			crdo-MTQ_KTM_F1_BANH-CHUNG_3 crdo-MTQ_KTM_M8_BANH-CHUNG 116 crdo-MTQ_KTM_M11_FAMILY crdo-MTQ_KTM_M13_WEDDING crdo-MTQ_KTM_F17_WORKING	October 23, 2018 October 28, 2018 October 30, November 1, 2018 August 16, 2019	0:05:14 0:02:03	0:03:13 0:03:25 0:01:03
			crdo-MTQ_KTM_F3_MINIMALSET crdo-MTQ_KTM_M8_LIFE 117 crdo-MTQ_KTM_M11_CULTIVATE crdo-MTQ_KTM_M13_MEDICINAL-PLANTS crdo-MTQ_KTM_F18_MINIMALSET	October 25, 2018 October 28, 2018 October 30, November 1, 2018 August 19, 2019	0:08:27 0:03:14	0:16:53 0:01:41 0:14:57
			crdo-MTQ_KTM_F3_BANH-CHUNG_1 crdo-MTQ_KTM_F7_MINIMALSET 118 crdo-MTQ_KTM_M11_TET-HOLIDAY crdo-MTQ_KTM_F14_MINIMALSET crdo-MTQ_KTM_F18_BANH-CHUNG	October 25, 2018 October 28, 2018 October 30, November 2, 2018 August 19, 2019	0:29:51 0:16:31	0:03:26 0:01:47 0:02:24
			crdo-MTQ_KTM_F3_BANH-CHUNG_2 crdo-MTQ_KTM_F7_BANH-CHUNG 119 crdo-MTQ_KTM_M11_CHILDHOOD crdo-MTQ_KTM_F14_BANH-CHUNG crdo-MTQ_KTM_F18_WORKING	October 25, 2018 October 28, 2018 October 30, November 2, 2018 August 19, 2019	0:05:39 0:06:54	0:04:34 0:01:09 0:01:53
			crdo-MTQ_KTM_F3_A-WORKING-DAY crdo-MTQ_KTM_F7_FAMILY 120 crdo-MTQ_KTM_F10_MINIMALSET crdo-MTQ_KTM_F14_FOLK-TALE_1 crdo-MTQ_KTM_F19_MINIMALSET	October 25, 2018 October 28, 2018 October 30, November 2, 2018 August 19, 2019	0:04:46 0:02:48	0:01:38 0:15:14 0:13:24
			crdo-MTQ_KTM_F3_CATCHING-FISH.wav crdo-MTQ_KTM_F7_TEACHING 121 crdo-MTQ_KTM_F10_BANH-CHUNG crdo-MTQ_KTM_F14_FOLK-TALE_2 crdo-MTQ_KTM_F19_BANH-CHUNG	October 25, 2018 October 28, 2018 October 30, November 2, 2018 August 19, 2019	0:03:53 0:01:43	0:02:13 0:03:14 0:02:26
			crdo-MTQ_KTM_F3_FAMILY crdo-MTQ_KTM_F7_CHILDHOOD 122 crdo-MTQ_KTM_F11_MINIMALSET crdo-MTQ_KTM_F14_FOLK-TALE_3 crdo-MTQ_KTM_F19_A-WORKING-DAY	October 25, 2018 October 28, 2018 October 30, November 2, 2018 August 19, 2019	0:06:59 0:02:11	0:02:50 0:13:41 0:01:09
			crdo-MTQ_KTM_F1_MINIMALSET_2 crdo-MTQ_KTM_M5_MINIMALSET 123 crdo-MTQ_KTM_F11_BANH-CHUNG crdo-MTQ_KTM_F14_FOLK-TALE_4 crdo-MTQ_KTM_F20_MINIMALSET	October 26, 2018 October 29, 2018 October 30, November 2, 2018 August 20, 2019	0:17:32 0:01:06	0:11:20 0:04:51 0:14:18
			crdo-MTQ_KTM_F1_BANH-CHUNG_4 crdo-MTQ_KTM_M5_BANH-CHUNG 124 crdo-MTQ_KTM_F11_A-WORKING-DAY crdo-MTQ_KTM_F14_ANT-SONG crdo-MTQ_KTM_F20_BANH-CHUNG	October 26, 2018 October 29, 2018 October 30, November 2, 2018 August 20, 2019	0:05:34 0:01:53	0:02:57 0:01:05 0:03:21
	N°Name of WAV file crdo-MTQ_KTM_F1_DOG_2 crdo-MTQ_KTM_M5_WORKS-IN-FARM 125 crdo-MTQ_KTM_F11_A-WORKING-YEAR crdo-MTQ_KTM_F14_LULLABY crdo-MTQ_KTM_F20_A-WORKING-DAY crdo-MTQ_KTM_F1_FUNERAL crdo-MTQ_KTM_M5_ANCIENT-LIFE 126 crdo-MTQ_KTM_F11_FAMILY crdo-MTQ_KTM_F15_LULLABY_1 crdo-MTQ_KTM_F20_DAUGHTERS	Date October 29, 2018 October 26, 2018 October 30, November 2, 2018 August 20, 2019 October 26, 2018 October 29, 2018 October 30, November 2, 2018 August 20, 2019	0:03:14 0:02:08 0:01:09 Duration 0:07:16 0:02:35 0:06:35 0:11:36 0:01:50 0:01:59 0:00:51
	2 3 4 5	1	crdo-MTQ_KTM_F1F3_BAMBOO-SHOOTS_1 crdo-MTQ_KTM_F1_SLAUGHTER crdo-MTQ_KTM_M5_LIFE-IN-WAR 127 crdo-MTQ_KTM_M12_MINIMALSET crdo-MTQ_KTM_F15_FOLK-SONG crdo-MTQ_KTM_F20_MUSIC-ACTIVITY crdo-MTQ_KTM_F1_BAMBOO-SHOOTS_2 crdo-MTQ_KTM_F1_MOSS_2 crdo-MTQ_KTM_M5_ALCOHOL 128 crdo-MTQ_KTM_M12_BANH-CHUNG crdo-MTQ_KTM_F15_ANT-SONG crdo-MTQ_KTM_F20_MOSS crdo-MTQ_KTM_F1F3_BAMBOO-SHOOTS_3 crdo-MTQ_KTM_F1_FAMILY crdo-MTQ_KTM_M5_FAMILY 129 crdo-MTQ_KTM_M12_FOLK-TALE crdo-MTQ_KTM_F15_LULLABY_2 crdo-MTQ_KTM_F1_WORDLIST crdo-MTQ_KTM_F1_WEDDING_1 crdo-MTQ_KTM_F1_WEDDING_2 crdo-MTQ_KTM_F8_MINIMALSET 130 crdo-MTQ_KTM_M12_ARMY crdo-MTQ_KTM_F13_FOLK-GAMES crdo-MTQ_KTM_F3_WORDLIST_P1 crdo-MTQ_KTM_F1_MOSS_1 crdo-MTQ_KTM_F1_A-WORKING-YEAR crdo-MTQ_KTM_F8F1_BANH-CHUNG 131 crdo-MTQ_KTM_M12_FAMILY crdo-MTQ_KTM_F13_LULLABY_2 crdo-MTQ_KTM_F3_WORDLIST_P2	October 2, 2018 October 26, 2018 October 29, 2018 October 31, November 2, 2018 August 20, 2019 October 2, 2018 October 26, 2018 October 29, 2018 October 31, November 2, 2018 August 20, 2019 October 2, 2018 October 26, 2018 October 29, 2018 October 31, November 2, 2018 August 20, 2019 October 2, 2018 October 26, 2018 October 29, 2018 October 31, November 2, 2018 August 21, 2019 October 2, 2018 October 26, 2018 October 29, 2018 October 31, November 2, 2018 August 21, 2019	0:03:49 0:01:20 0:02:24 0:04:40 0:00:14 0:03:23 0:07:38 0:01:18 0:01:35 0:19:12 0:06:34 0:09:43 0:02:11 0:04:57 0:01:22	0:02:43 0:22:17 0:01:29 0:02:49 0:08:02 0:01:05 0:03:05 0:00:56 1:41:54 0:06:43 0:04:51 0:52:51 0:03:42 0:03:36 0:59:05

SEAlang's website: http://sealang.net/.

https://www.zotero.org/groups/956729/vietic_languages_and_cultures.

The information of DO-RE-MI-FA project is available in https://lacito.hypotheses.org/251.

The Pangloss Collection is a digital library whose objective is to store and facilitate access to multimedia recordings in (mostly) endangered languages of the world. Developed by the LACITO centre of CNRS in Paris, the collection provides free online access to documents of connected, spontaneous speech. The Collection's website is: https://pangloss.cnrs.fr/.

The recordings can be listened to through the interface Telemeta: see http://archives.crem-cnrs.fr/ We are grateful to the curators of the archive for granting permission to access the master digital files for the purpose of the present research.

This set of seven figures constitutes a slightly improved version of those already presented in my M.A. thesis (M.-C.[START_REF] Nguyên | The tone system of Kim Thượng Mường: an experimental study of fundamental frequency, duration, and phonation types[END_REF]. The discussion of these figures is taken up from that earlier thesis without any major modifications.

The software package WinPitch (http://www.winpitch.com/) offers a range of algorithms for calculating speech fundamental frequency from audio signals. For this particular example, WinPitch's implementation of the AMDF method (Average Magnitude Difference Function) yields good results. My point here is not that f0 can never be computed for glottalized syllables, but that its computation is by no means straightforward, and that this topic is well worth investigating further.

2.3 Definitions: glottalization and creaky voice

Nhà Lang have been known as ruling class who have both rights and obligations to people in the place they control. In comparison with the Vietnamese (or Kinh) feudal landlord class, Nhà Lang can be assumed to have been more sensitive to the local realities. In Marxist perspective, Nhà Lang is praised as more "progressive", and as representing not only itself as a class but also the whole Muong community. Nhà Lang had a responsibility to help Muong residents in special situations such as drought, crop failure and famine and the planning and realization of major work (infrastructure work). In addition, they were in charge for the higher-level ceremonies of this region (see more in Cuisinier 1948).

Tân Sơn is a new district which was separated from Thanh Sơn district and established under the resolution 61/2007/NĐ-CP of the government from 09/04/2007.

Beginners can learn about the IPA by using the following two related web pages: (i) Interactive IPA Chart (https://www.ipachart.com/), where one can hear recordings of the sounds that the symbols represent, (ii) the IPA charts: sample translation batch (https://linguistics.ucla.edu/people/ keating/IPA/IPA_charts_2019_trans.html), a project to collect and post IPA charts whose metatext is in languages other than English -now including Vietnamese. There is also a free iPA Phonetics App for iPhone, iPod, and iPad from the Apple App store. This App provides an intuitive touch interface for exploring the International Phonetic Alphabet as well as numerous voice qualities and articulations.

For beginner-level information on creating and customizing an IPA keyboard on Microsoft Windows, a tutorial is available here: https://msklc-guide.github.io/

Henri Maspero used the term "Muong" to refer to all languages of the Vietic group except "Annamese" (Vietnamese)

Unless specified otherwise, "Vietnamese" refers to the Northern dialect, in its "standard" Hanoian variety.

This observation is found in a LabPhon conference presentation by Christina Esposito and Marc Garellek,

2018.Available: https://pdfs.semanticscholar.org/cc6e/ 3959782ff8158ba0315ba7fffec2aff71e42.pdf.

I am grateful to James Kirby for issuing this recommendation for the present study.

In Vietnamese, these forest farms are called trang trại: in addition to the main settlement, close to the paddy fields, families usually have a smaller farm higher up on the mountain, where they raise poultry and grow additional crops.

The entire slideshow could not be shown here due to the copyright of the photos on the internet. If anyone is interested, please contact me for a booklet.

AA means that this part always contains two digits. The digits from 1 to 9 are padded with a zero for a systematic annotation scheme that always contains 4 digits.

MATLAB is a technical computing language and interactive environment for algorithm development,

Note that the 10th column is set at 0 at this step and will be filled after user's O q dEGG verification step.

Technically, 'maxima' here should be referred to as 'minima', since the peak is a negative peak.

In this long chapter, I unpack a great deal of minor details and observations across tones and speakers, and thus the organization and division of sections and subsections is somewhat relative and, in some respects, a bit messy. Apologies if the reader finds it a bit difficult to follow along here.

Remember that 'smooth syllables' are those without final stops, and hence, the tones that appear on these syllables are commonly referred to in Southeast Asian linguistics as 'smooth tones'. Syllables with final stops are referred to as 'stopped syllables' or 'checked syllables', and accordingly, their tones are referred to as 'stopped tones' or 'checked tones'. This distinction relates to syllable structure, and not to the phonetics of the tones themselves. Thus, paradoxical as it may seem, Tone 4 appears on 'smooth' syllables and hence is one of the five 'smooth' tones, despite being, in impressionistic terms, not at all smooth to the ear, due to its creaky portion.

Recall that the formulas used to obtain these relative values of f 0 dEGG and O q dEGG are the same as inMazaudon and Michaud (2008, p. 238): see Section 3.4.

https://pangloss.cnrs.fr/corpus/Mường

https://github.com/covarep/covarep/releases

https://github.com/alexis-michaud/egg/releases

This user modification, carried out at the stage of semi-automatic processing the electroglottographic signals to extract f 0 dEGG and O q dEGG for all tokens, will then be stored in the final results matrix for the recording at issue. Therefore, when carrying out automatic creak detection down the line of the research process, the values taken into account are those in Figure

5.1d and not those in Figure5.1c. In case the measurements were re-run using PeaKDet in full automatic mode, without user verification, the values obtained would be those in Figure5.1c. These facts go without saying, as they result straightforwardly from the description of the workflow provided in section 3.3.3, but it seemed useful to state so nonetheless for the sake of explicitness and clarity.

This argument could also be extended to Beijing Mandarin. It has often been reported that the Beijing Mandarin third tone is occasionally accompanied by creaky voice. Some authors interpret this as a low-level phonetic consequence of a low pitch target for the third tone. But if this tone's phonation type were phonologically unspecified, one would expect various types of nonmodal phonation at low pitch in Mandarin, including cases of breathy phonation. It seems that observed cases are tilted towards creak, suggesting that appealing to universal phonetic factors does not tell the full story.

I also consulted[START_REF] Michaud | Glottalized and nonglottalized tones under emphasis: open quotient curves remain stable, F0 curve is modified[END_REF] and[START_REF] Brunelle | A laryngographic and laryngoscopic study of Northern Vietnamese tones[END_REF] to have a good understanding of Vietnamese B2 and C2.

This is not to say that glottal constriction may not serve intonational functions. In German, for instance, medial glottal constriction conveys negation in vocalizations that span the phonetic range between ['aʔa], ['mʔm] and ['ãʔã](Kohler, 1998, p. 269). But this is of a different nature from the Vietnamese facts, where there is no iconic relationship between the function of sentence-final particles and their phonation type, whereas there is a precise coincidence between these phonation types and patterns lexically associated with specific lexical tone classes.

The argument in this section is identical in its essentials with that published in Michaud, M.-C.[START_REF] Michaud | L'intonation dans les langues tonales : des réflexions générales et deux études de cas[END_REF].

The observations in this paragraph were reported in a journal article (in French): Michaud, M.-C.[START_REF] Michaud | L'intonation dans les langues tonales : des réflexions générales et deux études de cas[END_REF]

Obtaining images of the larynx during phonation, through laryngography, is a desirable complement to electroglottography, already used in pioneering research[START_REF] Esling | Laryngographic study of phonation type and laryngeal configuration[END_REF][START_REF] Brunelle | A laryngographic and laryngoscopic study of Northern Vietnamese tones[END_REF].

https://www.bas.uni-muenchen.de/Bas/software/speechrecorder/

The photos were downloaded between 2018 and 2019 from websites few of which provided information on author, persons appearing on the photo, or copyright; efforts to identify the original sources were unsuccessful, and hence no credits are provided in Figure A.6. Readers who can contribute such pieces of information are invited to contact me.

All the information about Roland 4-channel recorder can be found here: https://proav.roland.com/ global/products/r-44/.

Information of Sennheiser HSP4 microphone is available online: http://fr-fr.sennheiser.com/ microphones-serre-tete-hsp-4

Information of AKG C535EB microphone is available online: http://www.akg.com/pro/p/c535eb

Information about the Glottal enterprises EG2-PCX electroglottograph is available from the manufacturer's web page: http://www.glottal.com/Electroglottographs.html

The second microphone was also used when eliciting conversations -not studied here -, in which case it was worn by the second consultant.

https://pangloss.cnrs.fr/corpus/Mường

The highlighted colors here are not exactly those used in the figures because we also have to take into account the need for contrast with the black letters and tracings, for highest readability.

Acknowledgements

teacher, Sa Thị Đính, for her warm support during all my field and support along the way.

Needless to say, all shortcomings are my own responsibility. Financial support from the "Empirical Foundations of Linguistics" Labex project (ANR-10-LABX-0083) and the "Computational Language Documentation by 2025" ANR project (ANR-19-CE38-0015-04) is gratefully acknowledged, as well as financial support for fieldwork from LACITO and École Doctorale 622.

Finally I would like to extend my deepest gratitude to my

Pangloss Collection. In particular I would like to thank my Muong trips from 2014 to 2019. I would additionally like to thank Đinh Thị Hằng

Abbreviations

do not cross the threshold of smoo_deltaf 0 dEGG condition, whereas (ii) cycles from the 11 th to the 16 th are negative with zigzag pattern but positive over 20% change in the smoo_deltaf 0 dEGG condition. A minimally complex-repetitive pattern (double case) must occur in at least four successive cycles for there to be a repetition, so it could be said that this brief portion of two cycles is a false positive. The next positive portions from the cycles from 17 th to 28 th , and from 30 th to 35 th are separated by only one cycle 29 th . Technically, it is almost a detection of a long span of complex-repetitive pattern, but in fact, what can be observed from the signals in Figure 5.7c does not support this. It is far from a proper case of complex-repetitive pattern in multiply-pulsed creak.

The alternation between long and short glottal cycles in this case is not quasi-periodic, causing the change of f 0 dEGG to be formed as an irregular zigzag line. In short, with the initial CRPdet.m, the two conditions on the zigzag pattern and the smoo_deltaf 0 dEGG variable are intended to distinguish multiply-pulsed creak (case of double pulses) from jitter, through the different in magnitude of smoo_deltaf 0 dEGG , as well as from aperiodic creak, through the regular zizag pattern. However, the case of aperiodic creak here raised the issue of a possible false positive case with detected irregular zigzag patterns. Therefore, more conditions must be set to improve the accuracy of the function. Two sub-conditions of the third condition of the CreakDet.m function are provided for this purpose.

Listing 5.2: function "CRPdet.m" f u n c t i o n [ CRP_f0 , CRP_DECPA ] = CRPdet ( d a t a s h e e t ) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%% D e t e c t i o n o f complex -r e p e t i t i v e p a t t e r n s ( CRP ) %%%%% % t h e d i s t i n c t i v e c h a r a c t e r i s t i c s o f m u l t i -p u l s e d c r e a k . % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % I n p u t : a d a t a s h e e t from P e a k d e t .m % Output : CRP i s a v e c t o r t h a t c o n t a i n s a s many v a l u e s a s t h e r e a r e c y c l e s % i n t h e d a t a s h e e t . I t i s s e t a t 0 o r 1 d e p e n d i n g on whether t h e c y c l e a t % i s s u e i s p a r t o f a d e t e c t e d CRP span . %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Log : % 1 1 / 2 0 2 0 : t h e f u n c t i o n was c r e a t e d % 1 5 / 2 / 2 0 2 1 : S e p a r a t e CRP ( complex -r e p e t i t i v e p a t t e r n s ) from ZZP ( Z i g z a g % p a t t e r n ) . CRP i s p r e s e r v e d a s t h e i d e n t i f i c a t i o n o f d o u b l e -m u l t i p u l s e d % c r e a k , wh ere as ZZP d e t e c t s a l l o t h e r phenomena ( m o s t l y j i t t e r ) which a l s o % have a l t e r n a t i o n o f l o n g and s h o r t p e r i o d s ( f a u x CRP ) . % T h i s s c r i p t d e t e c t s complex -r e p e t i t i v e p a t t e r n s which i s t h e i d e n t i f i

The r a t e o f d e l t a f 0 ( s e m i t o n e ) % r a t e _ d e l t a f 0 ( i ) = ( d e l t a f 0 ( i ) / f 0 ( i ) ) * 1 0 0 ; % end % F o r c o u n t i n g number o f complex -r e p e t i t i v e p a t t e r n s ( CRP ) % To c a l c u l a t e t h e r a t i o o f CRP p o r t i o n i n whole s y l l a b l e . CRP_count = 0 ; % To d e t e c t t h e c y c l e s b e l o n g t o " r e a l " CRP we need an " i f " s t a t e m e n t % c o n t a i n i n g t h r e e c o n d i t i o n s : % ( i ) The main c o n d i t i o n ( C o n d i t i o n on s i g n i n v e r s i o n ) : % 4 s u c c e s s i v e d e l t a f 0 v a l u e s have t o be a l t e r n a t i n g between n e g a t i v e % and p o s i t i v e v a l u e s ; % ( i i ) The a d d i t i o n a l c o n d i t i o n # 1 : compare t h e s i m i l a r i t i e s o f two % s u c c e s s i v e " huge " c y c l e s which combined by one CRP component % ( 1 b i g c y c l e + 1 s m a l l c y c l e ) . % ( To do t h i s , s e t t i n g a t h r e s h o l d f o r t h e r a t e _ d e l t a f 0 o f ( k+k1 ) and ( k2+k3 ) % Th r e e t y p e s a r e d i s t i n g u i s h e d : % ( i ) complex -r e p e t i t i v e p a t t e r n s ( CRP ) : t h e d i s t i n c t i v e c h a r a c t e r i s t i c s o f m u l t i -p u l s e d c r e a k % ( i i ) a p e r i o d i c c r e a k % ( i i i ) ( t o an e x t e n t t o be v e r i f i e d ) s i n g l e -p u l s e c r e a k . %%%%%%%%%%%%% % I n p u t : a d a t a s h e e t from P e a k d e t .m ( and was s o r t e d by t o n e s ) % Output : < c r e a k > , a v e c t o r w i t h one v a l u e f o r e a c h l i n e i n t h e i n p u t < d a t a s h e e t > . %%%%%%%%%%%%% % No c r e a k d e t e c t e d : s e t a t 0 % S i n g l e -p u l s e d c r e a k : s e t a t 1 ( b a s e d on a measurement o f i r r e g u l a r i t y o v e r a g i v e n t i m e window ) % A p e r i o d i c c r e a k : s e t a t 2 ( b a s e d on p r e v i o u s c o n d i t i o n p l u s p r e s e n c e o f a ' z i g -zag ' p a t t e r n ) % Double -p u l s e d c r e a k : s e t a t 3 ( b a s e d on p r e v i o u s c o n d i t i o n s p l u s s i m i l a r i t i e s between a c y c l e and t h e s e c o n d n e a r e s t c y c l e ) %%%%%%%%%%%%%% % Log : % 3 1 / 3 / 2 0 2 1 : t h e f u n c t i o n was c r e a t e d u s i n g m a t e r i a l s from C R P d e t _ t e s t .m % 1 5 / 2 / 2 0 2 1 : S e p a r a t e CRP ( complex -r e p e t i t i v e p a t t e r n s ) from ZZP ( Z i g z a g % p a t t e r n ) . CRP i s p r e s e r v e d a s t h e i d e n t i f i c a t i o n o f d o u b l e -m u l t i p u l s e d % c r e a k , w her e as ZZP d e t e c t s a l l o t h e r phenomena ( m o s t l y j i t t e r ) which a l s o % have a l t e r n a t

i o n o f l o n g and s h o r t p e r i o d s ( f a u x CRP ) . % T h i s s c r i p t d e t e c t s complex -r e p e t i t i v e p a t t e r n s which i s t h e i d e n t i f i e d % c o n d i t i o n o f m u l t i -p u l s e d c r e a k ( c a s e o f d o u b l e -p u l s e d c r e a k , % t h e c a s e o f t r i p l e -p u l s e s i s n o t f o u n d i n my d a t a , hence i t i s n ' t t a k e i n % t o a c c o u n t h e r e ) . The i d e n t i f i e r o f t h i s p a t t e r n i n c l u d e s t h r e e c o n d i t i o n s : % ( i ) c o n d i t i o n #1 -ZZP : t h e a l t e r n a t i o n o f s h o r t and l o n g c y c l e s ( t h e % s t a r t i n g c y c l e can be e i t h e r a s h o r t o r a l o n g c y c l e ) . To d e t e c t t h i s % k i n d o f s i g n a l , we c o n s i d e r d e l t a f 0 o f e a c h 4 s u c c e s s i v e c y c l e s , i f % t h e r e a r e a l t e r n a t i o n o f p o s i t i v e and n e g a t i v e d e l t a f 0 . % ( i i ) c o n d i t i o n # 2 : s e t a t h r e s h o l d f o r s o o _ a b s _ r a t e _ d e l t a f 0 >=20%. % T h i s c o n d i t i o n h e l p s t o e l i m i n a t e t h e c a s e o f j i t t e r . ( t o be v e r i f i e d ) % ( i i i ) c o n d i t i o n #3 : The s i m i l a r i t y o f " combined c y c l e s " . % ( a combined c y c l e = a l o n g c y c l e + a s h o r t c y c l e ) % The combined c y c l e s need t o be a n a l o g o u s t o e a c h o t h e r . T h i s c o n d i t i o n

% h e l p s t o e l i m i n a t e t h e c a s e o f a p e r i o d i c c r e a k which h a s f a u x CRP % p a t t e r n , and t h e g l o t t a l i z a t i o n u s u a l l y o c c u r s a t t h e end o f s y l l a b l e s . %%%%%%%%%%%%%% % Trimming any empty l i n e s i n t h e d a t a s h e e t d a t a s h e e t = c l e a n z e r o s ( d a t a s h e e t ) ; % I n i t i a l i z i n g t h e v a r i a b l e s . % Output v a r i a b l e : c r e a k = [ ] ; f 0 = [ ] ; DECPA = [ ] ; % S t o r e i n p u t v a l u e s f 0 = d a t a s h e e t ( : , 3 ) ; DECPA = d a t a s h e e t ( : , 4 ) ; % C a l c u l a t i n g t h e number o f p e r i o d s o f t o k e n numb_period = l e n g t h ( d a t a s h e e t ( : , 1 ) ) ; % C a l c u l t a t i n g two i n p u t v a r i a b l e s f o r t h e d e t e c t i o n : ( i ) d e l t a f 0 and ( i i ) % r a t e o f d e l t a f 0 :

Appendices

Appendix 1: Challenges and strategies of phonetic experimental study in an unwritten language in the context of a bilingual community in the field No wonder that this piece of software, carefully designed by programmers working hand in hand with phoneticians, is a great success. The tool, which dates back to the beginning of this century [START_REF] Draxler | SpeechRecorder-a Universal Platform Independent Multi-Channel Audio Recording Software[END_REF], reached version 6 in 2020. Clearly, the way forward is in adopting such tools, which greatly facilitate data acquisition.

There is, however, one aspect in which the use of data acquisition software does not necessarily constitute an off-the-shelf solution: it assumes familiarity with digital tools and also (implicitly) with experimental protocols. Digital literacy and knowledge of data collection procedures are unevenly distributed among the population, and they are also unevenly distributed across the world map. Full success with SpeechRecorder and similar software can confidently be expected from most people who participate in data collection campaigns at phonetics institutes. While I am not aware of any study of the general demographic statistics of participants in data collection campaigns at phonetics laboratories worldwide, it seems likely that a fair share received college-level education. and stops, so I added the three corresponding nasals, /m/, /n/ and /ŋ/. (The two glottalized consonants /ɓ/ and /ɗ/ were excluded because they are expected to have strong coarticulatory effects on phonation type -a central topic in the study of tone. Aspirated /tʰ/ is alone in its series and was therefore left out too.) In a further effort to collect a set of data that would shed light on the full tone system of Kim Thuong Muong, I included, along with smooth syllables (syllables ending in a vowel or a nasal consonant, and carrying one of the tones from Tone 1 to Tone 5), some stopped syllables: syllables ending with a stop, and carrying tones 6 and 7 (the two tones of stopped syllables). In Kim Thuong Muong, there are four possibilities for a final consonant in a stopped syllable, namely /-p/, /-t/, /-c/ and /-k/. A quick check in the word list showed that, in the initial list available at the time, which contained 620 words, /-k/ was the most frequent final consonant (occurring in 44 words), the second most frequent being /-t/ (20 tokens), the third /-p/ (13 tokens), and the fourth and last /-c/ (6 tokens). Therefore, in terms of lexical frequency, /-k/ comes first. On the other hand, /-k/ has a strong identity in terms of coarticulation; in Vietnamese and Muong, this is reflected in entrenched patterns of coarticulation within the rhyme. In Hanoi Vietnamese, the rounding of vowels /ɔ u o/ moves onto final velar consonants; the phenomenon only affects velars. In other words, among the six final consonants /-p, -t, -k, -m, -n, -ŋ/ of Hanoi Vietnamese, the velar consonants /k/ and /ŋ/ have special patterns of coarticulation. This is not only the case after rounded vowels. Haudricourt in his study of 1952 showed that Vietnamese has a phenomenon of shortening of vowels in front of velar consonants, and of palatalization of the final after a front vowel, such as the realization of /ɛk/ as [ɛc], and /ik/ as [ic] [START_REF] Haudricourt | Les voyelles brèves du vietnamien[END_REF]. My own observations suggest that /-k/ in Kim Thuong Muong likewise tends to shorten a preceding vowel, so /-k/ was not selected for this experiment despite its status as the most commonly occurring final consonant.

In terms of formant movement, the final consonant that is likely to have the simplest coarticulatory influences is /p/: it lowers (slightly) the formants, especially at the transition from the vowel to the consonant, while /t/ has a stronger effect on the second formant (which tends towards a target of roughly 1,800 Hz) which is especially salient after back vowels, for example in the sequence /ut/, where a dramatic rise in the second formant can be found. In addition, /-p/, as a labial consonant, is the only consonant that does not conflict directly with the tongue position of the vowels. For those reasons, I chose /-p/ as a final consonant, hoping for data that would be easier to interpret.

To sum up, the final set of phonemes for creating target words consisted of: six initial consonants /p-, t-, k-, m-, n-, ŋ-/ The corpus of Experiment 2 was made up of the combinations of the above phonemes with 5 + 2 tones: 5 tones on smooth syllables and 2 tones on stopped syllables. Hence, we had [( 6 × 3 ) × 5 + ( 6 × 3 × 1 ) × 2] = 126 syllables in total (90 tokens of smooth syllables, and 36 tokens of stopped syllables). Each syllable was said twice, hence the total number of tokens was 126 × 2 = 252.

As an example of incomplete set, here is one of the four minimal sets in Table 3.1, in which we had already found three target words from the vocabulary list, namely:

1. /laj⁵/ "tongue" 2. /laj³/ "to return" 3. /laj⁴/ "to drive"

We first asked the consultant to confirm these three words, in order to verify if they really belong to the set, and also to clarify to the consultant what was the intended segmental make-up of the syllable for which we needed to find other tones. After that, we tried to pronounce the missing word(s) by combining the syllable with each missing tone, asking whether or not there exists such as word. She was able to find items with the two desired remaining tones:

1. /laj¹/, the first syllable of the compound word /laj¹ tɤm⁵/ which is "a bamboo fence to block lake drains to prevent fish from escaping through the gutter" (as shown in Figure A.4c) 2. /laj²/, which means "to carry stuff or people on motorcycle or bicycle (a twowheeled vehicle)". In cases where she could not find the words with the missing tones because they don't exist in Kim Thuong Muong, we switched to the solution of the near-minimal set. The rhyme and the tone are kept while the first consonant is changed with other consonants that have the same articulation mode and a place of articulation close to that of the reference consonant. The sets from the 9 th to the 12 th in Table 3.1 have been found this way.

A.3 Using illustrative photos to stimulate the target word: an appropriate method in unwritten language

Concerning the method of production, reading aloud the speech materials appears to be one of the most frequent choices because it is easy to implement and ensures consistency and accuracy of the data. However, Muong has no written form, hence reading was not an option. Indeed, in the previous study, we tried to borrow the Vietnamese alphabet for elicitation, as speakers of Muong are also proficient in this national language, and the failure of that experiment (despite various efforts) showed that it was clearly not the way to go. Vietnamese is so similar to Muong (maybe somewhat like German and Dutch, mutatis mutandis) that there is, in our experience, a high risk of interference between languages, creating experimental bias. To overcome this challenges, elicitation by means of photos appeared as the best choice. A strength of this method is that it increases the naturalness of the speech data, at least more than the reading method. Indeed, an inherent characteristic of reading a text is that people tend to speak more formally and articulate more carefully than when they are involved in a free conversation, which is good for phonological exploration but may eliminate some interesting phonetic variations. This method also allows for a relative control of tempo, avoiding the changes in speech tempo (i.e. speeding up or slowing down) that frequently occur in spontaneous speech (for a review, see Niebuhr Once all the photos had been selected, they were arranged into slideshows. This method appeared to be more optimal than using cardboard (carton cards) as had been done in my previous (M.A.) study, especially because the number of target words was relatively large. One risk to take into account, if the slideshow is shown on a laptop computer, is that the computer's fan will start making a whirring noise, which will compromise the quality of the recording. But apart from this potential difficulty, the digital method is relatively convenient for organizing and controlling the photos in the desired sequence: it makes it easy to replace photos with others that are more appropriate according to the participants' comments, and is particularly advantageous

Appendix B

Some practical details about the recording settings B.1 Equipment and experimental setup in the field

B.1.1 Recorders and microphones

I have occasionally heard the comment that technical detail about recordings in publications in linguistics is irrelevant, as devices now possess fewer specificities. Two digital (solid-state) recorders admittedly differ less than a Digital Audio Tape recorder and a compact tape recorder, for instance. But microphones remain widely different from one another, and so do electroglottographs, with consequences on the recorded data that do not seem negligible. Let us therefore go into some technical detail, with apologies to readers for whom some pieces of information seem superfluous (such as indicating the brand names of the equipment that was used). For want of having carried out comparisons between different equipments, it is not possible to tell whether (and to what extent) different results would be obtained with different equipment; information on the topic of recorders and microphones are offered with a view to completeness and explicitness.

For recording, this study used the Roland 4-channel recorder 1 (as Figure B.1a), which allows for the simultaneous recording of up to four channels. In the case of the present study, one of the channels was used for the electroglottographic signal, leaving three channels available for recording acoustic signals. This is a high quality recording solution that linguists can bring to their fieldwork locations. In order to use this recorder, the accompanying equipment needed includes:

•

B.1.3 Recording environment

All equipment was transported from France to the field work site by plane and then by taxi. They were safely transported in a solid and waterproof polyester suitcase. Due to the frequent high humidity in the area, except during recording, the equipment was always packed carefully in the suitcase and avoided being placed on the floor. The recording sessions were conducted directly in my Muong teacher's house (Figure B.4), where I stayed during the field trips. The Muong people have the custom of living on the upper floor to avoid feral animals. In the past, in the original architecture of traditional houses (i.e. nhà sàn), the first floor was used as a stable for buffaloes, cows or poultry. Today, they rebuilt it with bricks to make an extra room where their children can sleep and to store grain. Recording in this room has both advantages and disadvantages. The advantage is that with the wooden ceiling, and the rice bags filled in the house, the echoes of the cement walls are greatly reduced. Also, to minimize noise, the air vents are temporarily sealed with styrofoam. These conditions together with the high quality of the recorder allow the recordings to be relatively good from a technical point of view, despite the fact that the recordings were made on a farm, not in a recording studio.

On the other hand, the disadvantage also come from the issue of wooden ceiling. The fact is that, in long sessions of recording, it was unavoidable that family members walked in the upper room and made noise as the wooden floor is not solid enough. To remedy this, the recordings were usually carried out when family members were working in the fields, and they were asked to try walking lightly. Another problem was related to the hot and humid weather in the area. There was no other way, but a fan was used throughout the recording, despite the fact that it made noise. More importantly, this ensured that the speaker did not experience discomfort during the performance and did not sweat too much, which could have affected the recording of the EGG signal when the two electrodes were attached relatively tightly to the speaker's neck.

B.1.4 Recording set-up

Before each recording session, the recorder and EGG equipment were prepared in the following sequence of steps:

1. Place the EGG equipment (fully charged) (B.2a) on the table 2. Place the Roland recorder (B.1a) on the EGG equipment. Make sure a memory card (SDHC) is inserted inside. 3. Insert 4 batteries (B.1b) in the Roland recorder. 4. Plug the male connector of (i) three XLR-XLR cables (B.1e) into the first, second, and fourth female connectors on the Roland recorder, and (ii) an XLR-minijack (B.2b) into the third position. 5. Plug the two head mics into the phantom power supplies (B.1c, then into the females of the XLR cables which were connected to the first and fourth channels of the recorder.

6. Plug the table mic (B.1d into the female end of the XLR cable which was connected to the second channel of the recorder. 7. Plug the minijack of the XLR-minijack cable (B.2b, which was connected to the third channel of the recorder, into the EGG analog signal output (B.3a in the back panel. 8. Plug the dual-electrodes (G) in to the EGG equipment (A) (B.2a in the front panel. At recording, the position of these equipments was as shown on Figure B.5. The two main equipments, the Roland recorder and Glottal enterprises EG2-PCX, were placed on the table. The dual-channel electrode collar was attached to the neck of the speaker to measure the translaryngeal electrical resistance at two adjacent locations; these two signals are combined as the main EGG output, which thus occupies only one channel (the third one) in the resulting WAV file. Electrode placement was conducted as recommended by Nathalie Henrich, locating the last ring of the trachea and placing the electrodes above that point of reference. The input to the Roland steady-state recorder includes four channels:

• (i) the 1 st channel -audio signal: the first head mic, attached so that the microphone proper was above the corner of the mouth of the speaker; • (ii) the 2 nd channel -audio signal: the table mic was put in front of the speaker and on the table (the distance between table mic and speaker was about 30-40cm); • (iii) the 3 rd channel -EGG signal: the dual-channel electrode collar was attached to the neck of the speaker; • (iv) the 4 th channel -audio signal: the second head mic (in a similar position with first one) was worn by the investigator-instructor (to keep track of the dialogue). 5

B.2 List of files: main experiment and additional materials

This appendix provides a list of all the audio files collected during field trips in the course of the present study. It includes 224 audio files (the total recording time is around 27 hours and a half) falling into four categories: experiments about tone (including the files of the main experiment for the present thesis), vocabulary elicitation, narratives, and dialogues. My thesis only uses a fraction of this database. The rest is intended for use in further work, and for gradual improvement. There are plans for hosting these data in the Pangloss Collection, which already hosts Muong materials collected by Michel Ferlus from 1983to 1996. Some of my data on the experiment of minimal sets and pairs are already available from the Pangloss Collection 6 . All files are in .WAV format.

For reasons of page width, the following table only provides the following pieces of basic information:

N°Name of WAV file Date Duration

Appendix C

Data analysis and visualization

C.1 Labeling the tone system: numeric labels and association with colors

This section aims to draw attention to the way the object of this study -the tone system of Kim Thuong Muong -is labeled and displayed: the assignment of arbitrary numeric labels, and the association of tones with colors in a principled way. For ease of reference, each tone within the system is assigned a number, adopting a continuous numbering: from 1 to 5 for the five tones in smooth syllables, and 6 and 7 for the two tones in checked syllables. Such a way of labeling tone systems is common in synchronic studies of various tonal languages, such as Mandarin, a language for which the synchronic labeling of tones from 1 to 4 is adopted in phonetic-phonological studies [START_REF] Howie | On the domain of tone in Mandarin[END_REF][START_REF] Jongman | Perception and production of Mandarin Chinese tones[END_REF], sidestepping the diachonic complexities of the traditional categories of Chinese philology [START_REF] Jacques | Introduction à la phonologie historique du chinois[END_REF]. The ordering of tones when assigning them a number (or when drawing up a list of the tones when they have names of their own, as in Vietnamese and Middle Chinese) can, in principle, have a logic of its own, such as: simplest tone first, as in Vietnamese and Mandarin, lowest tone first, as in Joseph Rock's numbering of Naxi tones [START_REF] Rock | A Na-Khi -English encyclopedic dictionary[END_REF], or highest tone first, as in Fu Maoji's numbering of the same Naxi tones (Fù, 1981, p. 2). Frequency in the lexicon could also be a criterion (as, again, in Naxi, where both Joseph Rock and Fu Maoji list the Rising tone, a rare tone, at the end of the list, as the fourth tone). For Muong, the labeling by numbers has no such motivation: numbers were assigned to tones in the order in which they were discovered, in early stages of fieldwork, and the numbering was kept thereafter for the sake of consistency. Thus, the numbering does not follow any systematic language-internal logic. No clear and easy mnemonic associations between numbers and any property of the tones stands out a posteriori either.

A drawback of the numeric labels is that their lack of phonetic/phonological explicitness can make it difficult to remember them. In an effort to address this problem and create a degree of mnemonic association of the labels with the tones' phonological and phonetic characteristics, each tone is assigned a particular color. This is intended to create ties between the tones and the means used to represented them, with a view to making it easier for the reader to recognize the intended tones when they are mentioned by their numeric labels. Here we will clarify which colors are used to represent which tones, It needs to be emphasized that the color perception of the tones described here is based solely on my own impressions. Importantly, no claim is made that these impressions are a worthwhile path for accessing an underlying logic of the system and connect it to scientific (phonetic) observations. Thus, my impression that Tone 1 is like soft breath is clearly at variance with measurements of open quotient: if the tone were technically breathy, O q dEGG would be higher than for other tones, but (to preview results from Chapter 4) O q dEGG measurements for Tone 1 do not at all stand out within the five-tone system: technically, the tone is not phonetically breathy. The impressionistic description and scientific study are on two distinct levels. Others are likely to have different perceptions and opinions. The aim in assigning colors to tones is to provide a consistent visualization of tones, and thus help the reader and myself to quickly and effectively establish a relationship between the three dimensions: (i) the labeled tone, (ii) its representative number, and (iii) salient acoustic characteristics of the tone. A second criterion for the choice of colors has to do with visual clarity. We need to appraise to what extent the colors which by themselves appear suitable for the tones are in good contrast with one another, in order to facilitate and optimize visual inspection of the materials that display experimental results. In other words, colors are intended to bring out the tonal space and the nuances within this space. Achieving the five representative colors associated with five tones as used in all the figures in the present work. It can be seen that there are no pairs of colors in highest contrast, or in other words, in purely complementary relationship. However, the three colors blue (for Tone 2), green (for Tone 1) and red (for Tone 4) almost form a equilateral triangle in the colors wheel, which means that the contrast between those colors is fairly strong. Special mention needs to be made of the tinge of red chosen for the glottalized tone labeled as Tone 4. This tone is central to the present study; the choice of dark red as a color for this tone not only meets the first criterion (color sensations in response to this tone), but it is also suitable to set out the tone as a "star" within the system. According to color psychology, red is the most intense color, which can provoke the strongest emotions, and capture attention.

The above considerations constitute the main considerations in the choice of color combination for three of the five tones of smooth syllables. The other two get cyan (for Tone 5) and orange (for Tone 3). These have a analogous relationship with blue and red, respectively. Therefore, in order to enhance the contrast between these colors, we select the lightest colors in brightness scale for cyan and orange so that they contrast clearly with the darker colors previously selected.

A last step for this consideration is to test in practice how well the colors render together, and whether they allow for good legibility of figures that show the two main parameters discussed in the present work: f 0 dEGG and O q dEGG . Regarding those figures in Chapter 4, it seems fair to say that the colors match reasonably well, even at places where the tones overlap. These considerations seemed to vindicate the choices made here.

One more note for this section is that there are differences between highlight colors used in the thesis (in L A T E X format) and colors in figures produced by MATLAB. The reason is that we must take into account the color contrast for better readability and visibility since the highlighted colors within the text are surrounded by black letters whereas in the figures the colors display the f 0 dEGG or O q dEGG lines against a white background. The solution is that we attempt to select relatively similar colors but in different tinges and shades in the L A T E X palette compared to those chosen in MATLAB so as to maintain an effective association of colors to the label names of tones. Especially, the three dark colors of green, blue, and red selected for Tone 1, Tone 2, and Tone 4 in plotting figures are adjusted to much lighter colors in the text. We considered and selected the exact colors by consulting the list of ready-to-use RGB triplets codes from L A T E X (here) and MATLAB (here).

Needless to say, these quick remarks leave many topics unaddressed, such as the issue of data access for color-blind readers. I apologize for this shortcoming, which readers with different sensitivities to color can remedy by relying on the different shapes of the marker symbols used for different tones.

Appendix D Additional graphs produced as a result of this study

This appendix provides an additional set of figures that were plotted to visualize the results of this study but were not presented in the Results and Discussion chapters. Vietnamese (with which Muong is in sustained language contact). However, the phonological discussion emphasizes that analysis of Tone 4 as a prototypical "creaky tone" would be a pitfall. Tone 4 behaves in key respects like the other tones in the system: it is not defined solely by phonation type. Moreover, the range of phonetic (allotonic) variation of Tone 4 includes cases of glottal constriction. Use of a phonetic nomenclature for types of glottalization serves as a basis for describing the interaction of glottalization with intonation.

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