Denis-Constant Martin

Nina S De Fridemann

Politics Behind The Mask : Studying Contemporary Carnivals in Political Perspective, Theoretical and Methodological Suggestions 1

Carnivals are a type of rite of renewal where mask and laughter spur the invention of highly symbolic modes of expression. They offer opportunities for the study of social representations and, since they are both recurring and changing, they constitute a ground where not only social change can be assessed, but where the meanings of social change can be best understood. The first part of this paper reviews and discusses theories of carnival, in particular those related to its relationship to power and social hierarchies. The second part proposes a few methodological suggestions for the study of carnival from a political perspective, emphasizing semiotic analysis and surveys using non-directive methods.

Résumé

Les carnavals constituent un type particulier de rite de renouveau dans lequel le masque et le rire entraînent l'invention de modes d'expression à forte densité symbolique. Les carnavals fournissent ainsi le champ privilégié d'une recherche sur les représentations sociales; parce qu'ils sont à la fois récurrents et changeants, ils offrent la possibilité d'évaluer non seulement les changements sociaux, mais surtout les significations portées par ces changements sociaux. La première partie de ce texte présente et discute différentes théories du carnaval, notamment celles qui traitent de ses relations au politique et aux hiérarchies sociales. La seconde suggère quelques éléments de méthode pour étudier les carnavals dans une perspective politique et propose que l'analyse sémiotique soit combinée avec des enquêtes par entretiens non directifs.

Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm 4 into an episode in the fight between the Kings' conception of an absolute central authority and the aristocratic frondeurs attempting to retain some of their autonomous power; they were eventually defeated. 5 The attempted revolt that sprang from the 1970 carnival in 8 Bercé,op. cit.,p. 198. 9 Roberto Da Matta, Carnavals, bandits et héros, Paris, Le Seuil, 1983; see also: "Constraint and licence: A preliminary study of two Brazilian national rituals" in S.F. Moore, B.G. Meyerhoff (eds.), Secular Ritual, Assen, Van Gorcum, 1977, pp. 244-265, and "On carnival, informality and magic: A point of view from Brazil" in E.M. Bruner (ed.), Text, Play and Story: The Construction and Reconstruction of Self and Society, Washington (DC), American Ethnological Society, 1984, pp.230-246. power systems are displayed and actually preserved in Rio de Janeiro's Carnival: she clearly points up the order in the disorder, the consolidation of the existing social system behind its apparent temporary upheaval.

11 Indeed, Mikhail Bakhtin 12 emphasized to what extent Medieval carnivals made possible the emergence of a vision of the world upside down, but it should not be forgotten that: a) his ideas stemmed from the analysis of a corpus of literary works -he dealt with Rabelais' world, not with historical accounts of Medieval and Renaissance carnivals -and that an examination of a different corpus brings to the foreground other conceptions of carnival during the same periods, focusing, for instance, on the contest between Carnival and Lent, a cyclical confrontation in which Carnival is not always the winner; 13 b) the keyword in Mikhail Bakhtin's analysis is probably not "inversion" but ambivalence; there is no absolute and abstract negation in popular festivals; at work is rather a contradictory unity, for every element of carnival focuses on the wholeness of a world that is both in the throes of death and rebirth.

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Discussing the diverging views held by Maria Isaura Pereira de Queiros and Roberto Da Matta, anthropologist Michel Agier proposes a synthesis: during carnival several modes of ritual invention operate side by side and produce different types of relation between festival and social reality. He also stresses the ambivalence of carnival and suggests that the juxtaposition of various, sometimes contradictory, rationales of the imagination, constructs a distorted -and not an inverted -reality.

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Consequently, although they may contain elements of inversion rites, carnivals do not imply an upsetting of social orders and power systems. They simultaneously allow for the display of social hierarchies and their temporary abolition; they usher in times and they 11 Maria Isaura Pereira de Queiroz, Carnaval brésilien, le vécu et le mythe, Paris, Gallimard, 1992.

12 Mikhail Bakhtin, Rabelais and his World, Bloomington, Indiana University Press, 1984. open spaces for social and political commentary, some of which can be quite caustic and openly directed at rulers; but in the end, social and political orders are almost always restored: "Carnivalesque festivals amount to a consolidation rather than a threat because they are haunted by a foreseen return to order, to harmony and to fecundity, which they have to ensure [...]." 16 This does not mean, however, that carnival is devoid of politics. On the contrary, carnival is saturated with politics, but this transpires essentially at the symbolic level. Carnival allows for the expression, juxtaposition and combination of imaginations which, Michel Agier notes, contain a high potential for symbolic creation. It ensues that carnival can be analytically approached as an occasion when social representations17 of society and power can be shown and enacted with all their complexity and contradictions.

Imagination, emotions, forms of collective behavior, objects and practices invested with feelings of belonging and symbols of good and evil which are displayed during carnival can be adapted and used in political struggles by the rulers as well as by the dominated classes. 18 The politics of carnival takes place mostly behind the mask, in a disguised fashion.

Studying carnival in terms of imaginative rationales, symbolism and social representations can tell us more about the relationship between rulers and the ruled than

THE SYMBOLISM OF LIFE AND DEATH

In a nutshell, carnival is a particular type of renewal rite performed in almost every human society; it stages a play on life and death; and because it deals with fertility and the permanence of life, it is closely linked to representations of power.

A rite of renewal

In European Catholic societies, as well as in those which have been colonized by states where Catholicism was predominant, the adaptation of the Christian calendar to solar or lunar calendars previously used caused spring festivals to be celebrated between Carnivals stage the essential drama common to all human beings, the struggle and complementarity of life and death; they create an occasion to stage this drama periodically and use the opposition between life and death as a backdrop to the individual's existence within various social groupings. Personifying and enacting the idea of renewal, revelers demonstrate that collective life is indestructible, irrespective of the demise of individuals.

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They symbolically enunciate prerequisites for the victory of life that any community must fulfill in order to survive: abundance (thence the profusion, exchange and occasionally deliberate wastage of food and drink) and fecundity (often transformed by the spirit of grotesque and laughter in ubiquitous obscenity). What is ultimately at stake in carnivals is biological and social reproduction that can only be carried on by the individual as a social being. Carnivals provoke and display differences and complementarities, oppositions and interactions (from sexual differences to social differences). They play on barriers, limits and boundaries: relative to time, space and social groups, in order to create possibilities for overstepping them, [START_REF] De Friedemann | Perfiles sociales del carnaval en Barranquilla (Colombia)[END_REF] transgressing them and confusing them. In order to blur limits and boundaries or cross them, two devices are chiefly used: masks and laughter. A mask is to be understood as any decorative device which allows the individual to change his or her appearance. It can hide the whole body (like Touloulous' costumes in Cayenne, French Guyana); it can transform a human being into an animal (like the bear in many a European carnival) or into a new being part human, part animal (like the hobby-horse, the burroquite frequently encountered in Spain) or any fantastic creature (such as the ones invented by Peter Minshall in Port of Spain, Trinidad); it can adorn the partially naked body, transfiguring it with a few decorative items (a common sight in Rio de Janeiro or New Orleans). Possibilities are infinite, but the mask always gives the reveler the chance to look like someone, sometimes even like something, else. For Mikhail Bakhtin, the mask is Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm 12 one of the most complex elements of popular festivals, it negates unitary conceptions of the self, it playfully permits changes and reincarnations;

34 "masking," concurs Samuel Kinser, "stimulates expression of the self's multiplicity." 35 Behind the mask, a reveler can be at the same time him/herself and another with whom he identifies, even partially or ephemerally.

Masks may be created individually, 36 or may be selected among those proposed by different, often competing bands or troupes, but they basically play the same role.

Port of Spain (Trinidad), 1989. The body (…) transfigured by a few decorative items. [START_REF]Cherchez le peuple..., culture, populaire et politique[END_REF] Mikhail Bakhtine, op. cit., p. 49. 35 Samuel Kinser,op. cit.,p. 275. 36 See the novel by Trinidadian writer Earl Lovelace: The Dragon Can't Dance, London, André Deutsch, 1979. Laughter -any manifestation of grotesque or witty humor -defuses anxieties inherent to the enactment of the drama of life and death and tensions caused by the display of social contrasts and power relationships. It explicitly magnifies the reproductive parts of the body, or symbolically and comically evokes sex; it emphasizes abundance and prosperity; it even conjures dearth through excessive consumption and waste. Drollery and facetiousness are used to deal with serious matters, from death to power; they may function like safety valves, but also channel discontent and revulsion caused by injustice, dishonesty or ineptness, especially on the part of those who hold power. Laughter is a way of proffering untold truth about the world in which people live, it suggests the possibility of another world, 37 its transgressing power may fuel corrosive social criticism.

38 37 Mikhail Bakhtine,op. cit.,pp. 57,[79][80] Among the traditional characters of the Vallée de Soule masquerade, the "Blacks" (in this case a particular group of masqueraders wearing mostly black cloths) impersonate disorder, obscenity, transgression and laughter; at specific times in the masquerade, they give speeches and sermons where they vent criticism and attacks against notables and authorities at the local, provincial, or national level. See: Eric Dicharry, art. cit.

The study of laughter in carnival shows that it facilitates the free association of opposition and discontent, but it also shows that explicitly articulated opinions are always built upon symbolic foundations. A good example is provided by mock trials of Carnival or

Carmentran (a name used in French Provence, meaning Entering-Lent). The "prosecutor's" indictment against Carnival is an occasion for recapitulating all the events that caused dissatisfaction during the year, actions -or inactions -of those in power included. The condemnation and execution of the character embodying Carnival -playing the role of scapegoat -can be interpreted as a cleansing ritual whereby all grudges and grievances are disposed of, and his resurrection as the new start of a reunited community. In this example, some of carnival's fundamental ambivalences appear clearly: symbolic and open expressions of social and political criticism are intertwined; the behavior of those in power may be exposed, they will keep their charge while it is Carnival or Carmentran who is burnt, hung or shot.

Symbolism underlies all carnival idiom, whatever particular means of expression or combination of these means they use: words, costumes, makeup and masks, music, body movements, emblems and banners, objects, etc. Symbolic codes of course vary from place to place and always have to be contextualized before they can be interpreted. 39 However behaviors frequently seen in carnivals and renewal festivals may carry identical or similar meanings in various cultures. For instance, the act of throwing -usually a liquid, sometimes other objects (flour, seeds, fruit, streamers, nowadays chemical sprays)obviously mimics ejaculation and has to do with fertility and reproduction; the fact that it is based on and suggests a function which is both biological and social and ensures the continuity of life, probably explains why it is so frequently encountered. Fire may signify destruction or purification and regeneration; indeed quite often it combines both meanings.

Other symbols usually form contrasting systems evoking the opposition of life and death, while blurring and confusing the limits which are supposed to separate them by transforming oppositions into sequences, by creating combinations and provoking overlapping, which all amount to obliterating the initial contradiction existing between opposites. The most common pairs of elements opposed, juxtaposed and mixed during carnivals are: day and night, also light/brightness/colors and darkness/dullness; cleanliness and dirtiness/filthiness; tumult/noise and silence/music; culture/civilization and bestiality/savagery; human and devilish or ghostly; order and disorder; self and other.

Basel, 1994. The act of throwing

Order and disorder, the self and the others

The opposition and combination of order and disorder, of the self and the other are indeed central to all rites of renewal. Carnivals allow disorderly behaviors to be freely displayed within social frames where they are normally not allowed. However, carnival disorders, taking place within agreed temporal and spatial limits, are not meant to last; on the contrary their main function is to lead back to normal conditions of order, and first of all, to demonstrate the necessity of a social order, therefore the need for an authority capable of enforcing it. Ritual disorder, as it occurs in carnivals, is a mechanism which evinces the necessity of political power. "Order and disorder," writes Georges Balandier, Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm 16 are like the obverse and the reverse of a coin: inseparable [...] Disorder may become a negative thrust and generate a world which looks upside down; however, it is a well known fact that the inversion of order does not cause its abolition; disorder can be used to reinforce order, or to allow it to be reborn under a new figure [...] Since disorder cannot be contained, since it is actually necessary, the only option is to transform it into an instrument of positive labor, that is to use it so that it neutralizes itself at least partially, or to change it into a mechanism producing order. Here again, these confusions and combinations only last as long as carnival; when it is finished, the individual is sent back to what his or her self is exclusively supposed to be, the "outsider" no longer has, as such, the same functions. Political authorities recover the power to define who is a member of the constituency they rule: who is a citizen, a legal resident with restricted civil rights, or a "foreigner." 40 Georges Balandier, Le désordre, éloge du mouvement, Paris, Fayard, 1988, p. 117. 41 Georges Chaluleau, Jean-Luc Éluard, op. cit. 42 Michel Revélard, op. cit. 43 The place granted to "foreigners" in the Soule valley masquerade is fascinating in this perspective: in addition to characters representing the Souletins (inhabitants of the Vallée de la Soule, speaking a dialect of the Basque language), there is a profusion of Béarnais (from Béarn, the province next door where a dialect of Occitan is spoken), Auvergnats (also Occitan speaking people from the south-center of France), Bohemians, all indeed played by Souletins, without whom the masquerade, as the ultimate manifestation of a feeling of belonging to the Soule valley, would not be complete and the ritual could not be compeleted. See: "Maskaradak, Züberoko herri ihauteriak / Les mascarades, carnaval populaire de Soule," SÜ AZIAren sail bereziak / Les cahiers de SÜ AZIA, 2, 1993.

From the power to kill and let live to a play on life and death

The interplay of order and disorder as well as that of the self and the other indicate that there indubitably exists an intimate connection between carnival and politics. This connection is definitely a fundamental one, for if carnival stages the drama of life and death, power begins with the power to kill or let live. It was clear in ancient times, both within the family and in larger social organizations, and was derived in many civilizations, in particular of the Judeo-Christian tradition, from the divine anointment of earthly rulers (the story of the Flood, Abraham's consent to obey God's order to sacrifice his only son, are but two illustrations that the power to create was, in this system of thought, counterbalanced by the power to destroy; Genesis 7 and 22). That the power to kill underlies political power is still evident in contemporary states: where the death penalty has not been abolished, the head of state has the prerogative to grant a pardon; everywhere, he or she can send soldiers, including drafted citizens, to war, and when atomic bombs are available, the chief of the executive is the one who decides on its use. For these reasons, and more, Pierre Legendre, law historian and political scientist was led to write: "Even democratic, power is unbounded [...] if it is not controlled and contained, it becomes a Terror that can bleed to death the people it rules." 44 To him, the "anthropological kernel" of law is the fact that the power to create institutions is equivalent to a power of life and death over the subject.

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Similarly, political power -including the executive, the legislative and the judiciary -manages the relations of individuals with collectivities. At the national level, it determines who is a citizen and who is not; it can grant citizenship to persons who do not enjoy it and strip people of their citizen's rights. At the infra-national level, it passes legislation governing the right to assemble and associate and to form groupings and organizations of all natures.

Power establishes limits between what is allowed and what is forbidden, and delineates boundaries between groups, beginning with distinctions between citizens and non-citizens.

44 Pierre Legendre, La fabrique de l'homme occidental, Paris, Mille et une nuits / Arte éditions, 1993, p. 17.

45 Pierre Legendre, "Ce que nous appelons le droit," Le débat, 74, mars-avril 1993, pp. 107-122; for a more thorough exposition of Pierre Legendre's conceptions of power, of the place of law and of the role of institutions, see: La 901 e conclusion, étude sur le théâtre de la Raison, Paris, Fayard, 1998.

Finally, the primary function of political power is to ensure the safety of the community, therefore to guarantee its capacity to maintain and reproduce itself. It must foster affluence and abundance; to that end, it can adopt specific policies to regulate the community's birth rate, either by encouraging or discouraging procreation.

Life, death, prosperity and abundance, reproduction and procreation are some of the strongest links that connect carnival and politics. Historically speaking, it is striking that the emergence of centralized political authority in Mesopotamia coincided with the invention of renewal festivals performed at the New Year, 46 a link that has never been severed. It ensues that the connection between power and carnival can be considered from two different points of view.

On the one hand, one has to look at the role(s) various authorities (be they many examples of both. Revelers find in carnivals openings that enable them to vent their feelings about the power system and the performance of those in power. They can also take this opportunity to renegotiate their identity by opposing their own conceptions of who they are to the rulers' vision; European workers did it in the past, and the issue of "coloured" identity always underlain Cape Town's Coon Carnival

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. 46 Georges Roux, La Mésopotamie, essai d'histoire politique, économique et culturelle, Paris, Le Seuil, 1985, pp. 334-337. 47 The part played by local authorities in the organization of carnivals in several French towns is studied in: Alexandra Echkenazi, "Les collectivités locales en habits de carnaval," La gazette des communes, 14 février 2000, pp. 32-35. Samuel Kinser also discusses the support granted by the City of New Orleans to Mardi Gras celebrations; the presence of the police is illustrated with a superb picture of policemen wearing plastic pig snouts... (op. cit., pp. 294-299).

More generally, carnival provides an occasion to express, contest or adjust social representations. Carnival actually constitutes one of the few sites where social representations, which are never altogether explicitly articulated, which are never totally spoken, can be apprehended. Social representations form a shared body of implicit images of and ideas about the society in which a group lives and the makeup of their social environment. Depending on the cultural codes particular to each group, images and ideas symbolize elements of the environment in order to make sense of it and to make action on and in it thinkable and feasible. In the words of Denise Jodelet, social representations are "[...] a type of knowledge, which is socially constructed and shared, which is geared to practical ends, and which contribute to the development of a reality specific to one particular social ensemble." 49 Given the strong connections between carnival and power, carnivals are certainly an effective vehicle for the symbolic expression of social representations of power.

The multiple modes of expression activated during celebrations and the highly symbolic nature of carnival practices offer ways and means to escape the censorship of verbal language and the exclusive logics of politics. In carnival, ambivalent and contradictory attitudes towards power can be expressed at the same time. Conceptions that can hardly be verbalized are staged, enacted, mimed, played, danced, sung, put in colorful outfits, paraded on floats or hidden within a dummy. Taken as a whole, carnival looks like a kaleidoscope in which bits and pieces of social representations of power form, separate and reform another figure. The fleeting appearance of representational elements at the surface of carnivalesque events makes it difficult to grasp and analyze them; however, the recurrence of carnivals, their local nature, in some cases the social origin of their participants, are all factors that invite the analyst to try and overcome the difficulties and undertake research aiming to bring to light the underlying representations of power in carnivals.

A TENTATIVE METHOD FOR THE SOCIO-POLITICAL STUDY OF CARNIVALS

To conduct an investigation on politics and carnivals (or politics in carnival), a specific method must be devised in order to take into account both official connections, that is, the interactions between political authorities, carnival organizers and revelers, and symbolic links: social representations of power which may be expressed in a disguised form during festivities. I shall present some suggestions with a view to elaborating such a method, summarizing an approach I have developed in my own research on carnivals in Port of Spain and Cape Town, and more generally in my studies of political culture and popular culture. 50 This being still very much a work in progress, my ambition is to stimulate a methodological discussion, but certainly not to propose any kind of recipe.

General description

Obviously, any study of carnival should include basic information on the context in which it takes place, that is, on the place where it is staged (village, neighborhood, town, region, country), the people who form the core group(s) of revelers (in terms of social status, origin, gender, religion, etc.), and the social and political relations prevailing at the time of the study. The history of the festival should be recounted in relation to the historical background of the society that accommodates it.

The carnival itself must be described in detail. The various places where it takes place must be identified: free public spaces (streets, squares, roads), paying public spaces (stadiums, concert halls, ad hoc structures like the sambadrome in Rio de Janeiro) and private spaces (halls where fêtes and exclusive balls are held, private homes). Links 50 Denis-Constant Martin, "Popular culture, identity and politics in the context of the Trinidad carnival: 'I is another, all of we is one'," Studies in History, 12 (2), July-December 1996, pp.153-170; Coon Carnival..., op. cit between these spaces must be reconstructed: temporal links (succession, and order of succession, or simultaneity in the use of spaces under consideration); spatial links (tracing official or unofficial itineraries, and locating the various carnival thoroughfares and stops that compose a symbolic map of carnivalesque space).

Carnival being considered as a rite of renewal and constituting a cycle within larger cycles of human life, a detailed description of its timeframe is of the utmost importance. The succession of periods and events must be noted, with the particular names that may be given to them; a distinction should be made between permanent activities (troupe leaders may work all year long to prepare their group for carnival; organizations may have full-time employees; the conception and making of their costume may keep revelers busy for a long time) and periodical activities: various stages of preparation and rehearsals; events which are seen as forerunners of the main festival; the days which are considered as carnival proper; and the events that really bring carnival to an end until the following year. The full cycle of carnival can thus be reconstituted and its ties with other cycles examined, be they public or private, festive or solemn.

Great attention should be paid to the type of event included within the particular carnival under study: balls and fêtes; home-to-home visits; street parades; neighborhood or village gatherings, or gatherings in front of particular buildings, especially official ones; displays, concerts and shows set up in designated places. Some festivals are highly competitive (Trinidad, Cape Town); others are less so (Basel), or not at all (Aosta, Italy).

Some have been ritualized to the extreme (Binche) and the same types of events have been taking place in the same order for several decades (but not necessarily for several centuries as participants sometimes claim), while others, though retaining permanent features, offer mainly a field for collective improvisation (Dunkirk, northern France). In a few cases, musical repertoires are established (Binche; Limoux; Lanz, Basque country, northern Spain), or certain songs are emblematic of the celebration (Dunkirk); in others, musical styles are associated with carnival, but new songs must be introduced every year (Trinidad); in Cape Town, both fixed and permanently renewed repertoires are to be heard.

The aesthetics of carnival may be rigid or flexible. In some carnivals, costumes and masks define characters and roles, and remain unchanged year after year (Binche, Aosta, Basel, Soule valley, Lanz); in others, the rule is to keep the same style but to change patterns and colors (Cape Town); elsewhere, new costumes and masks must be imagined every year (Trinidad, Rio de Janeiro). However, in many instances, even where costumes must be changed, some characters must appear: the bear in Aosta and the Pyrenean valleys of southern France, moko jumbies (stilt walkers) in several West Indian islands, red bulls in Martinique, burroquites and smiths in the Basque country. Masks may cover the whole body or reveal it, adorned with decorative items and makeup; it is interesting to note where and when revelers must not be recognized (the Touloulous of Cayenne; those who "intrigue" on others in northern France and Belgium). Parts of the outfit may have a particular importance: hats for instance, or umbrellas, or facial ornaments. Other objects can be part and parcel of carnival and acquire great symbolic significance; this is the case of the Basel lanterns, of "Giants" in Flanders (Belgium and northern France) and Olinda (Brazil), of troupes' boards (carved or decorated emblems) in Cape Town.

Aosta Valley, 1993.

The bear in Aosta. In many places, troupes select a different topic every year; they may even change names. In these cases, an analysis of the succession of topics, of the various costumes associated with them, their names, possibly the musical anthems they have chosen, sheds light on events or topics likely to attract people at a particular juncture, that is, on social representations and their transformation.

51 Samuel Kinser provides a list of "semes" used in his analysis of New Orleans Mardi Gras (op. cit., pp. 321-323) which, to a large extent, runs paralel to the list given in the previous paragraphs of this paper, and Michel Agier included an appendix in his study of carnival in Bahia where he discusses the main anthropological theories of carnival and proposes methodological guidelines to analyze it (op. cit., pp. 225-241).

52 See: Denis-Constant Martin, "The burden of the name...," art. cit.

53 Or part of it: the influence of military herarchies is frequently felt in the organization of troupes and names given to their officials.

bring back life to normal 60 -that is, to submission to existing systems of power -are important to understand underlying conceptions of power.

Space

Spaces are also relevant in such a perspective: many carnivals allow for temporary occupation -an ephemeral takeover -of particular places by groups of people who either are not normally allowed there, or are not generally considered as belonging there. The typical scenario is when subaltern social strata, living in neighborhoods located on the outskirts of the city, parade in streets and squares of the upper-class town center. The most striking example is probably apartheid Cape Town, where "coloured" people fought for their right to march in areas designated as "white," but similar scenarios have been enacted in many societies divided along social or racial lines. Itineraries followed by group of revelers show which spaces are symbolically important; they usually go from the periphery to the center. A good example is when costumed inhabitants of Dunkirk converge and assemble on Town Hall Square: they claim ownership of the town as a whole and demand from the Mayor that he throws fish or seafood from the Town Hall balcony: a reminder that the authorities must ensure abundance and that Dunkirk's economy used to derive from the sea.

Identity

Troupe membership may reveal social boundaries: participants come from particular neighborhoods or social milieus, often both; troupes and consequently milieus compete and 60 Triumph of the winners in competitive carnivals (Cape Town, Trinidad); death and resurrection of the main character in the ritual (Soule valley); destruction of evils and cleansing by fire (Lanz): the end of carnival looks like the opening of a positive way back to normality. Revelers have enjoyed a pleasure which cannot be reached at other times of the year, symbolic changes have taken place which do not deeply alter structures of power and social hierarchies, but the energies necessary to cope with "real" life have been renewed. interviewees, but the dynamics of the discussion which takes place between the interviewees, with minimal interviewer interference, allow for a freer expression of feelings and attitudes and a wider coverage of the various aspects of the phenomenon which is being researched

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. Both individual and group interviews may be started on a general prompt dealing with the event under study; for instance: "what does carnival mean to you?"

Other non-directive methods may also be used, such as asking interviewees to tell the story of their life, showing pictures or videos of the carnival, possibly associated with pictures and videos of other carnivals.

After a series of interviews have been recorded, they are carefully transcribed and analyzed according to usual techniques. 65 In the case of an in-depth, non-directive interviews may be used as a preliminary investigation to write a questionnaire, followed by a quantitative survey.

CONCLUSION

Carnivals are a particular type of rite of renewal; their roots can be found in ancient civilizations; yet they are still performed today and there are signs indicating that in many places they are undergoing a revival. They are undoubtedly an important social phenomenon. This is all the more true since they are both recurring and changing: they constitute a ground where not only social change can be assessed, but where the meanings of social change can be best understood. 64 For an exemple of the use of group interview in the study of representations of society and power present in a carnival, see: Denis-Constant Martin, "Memories, historical consciousness and the new South Africa, representations of change among youths of the Cape Flats," in: Jocelyn Létourneau (dir.), Le lieu identitaire de la jeunesse aujourd'hui, études de cas, Paris, L'Harmattan, 1997, pp. 89-109.

65 Guy Michelat, "Sur l'utilisation de l'entretien non directif en sociologie," Revue française de sociologie, 16, 1975, pp. 229-247; Henri Raymond, "Analyse de contenu et entretien non directif: application au symbolisme de l'habitat," Revue française de sociologie, 9, 1968, pp. 167-179; Tatiana Yannopoulos, Denis Martin, "De la question au dialogue, à propos des enquêtes en Afrique noire," Cahiers d'études africaines, 18 (3), 1978, pp. 421-442. There are strong connections between carnival and power, including political power.

These connections justify studying carnival from a political perspective and especially attempting to uncover social representations of power in the highly symbolic carnival event.

Beyond a necessary description of the events composing carnival, the particular links tying carnival and power suggest fields where social representations of power can become manifest: these are time, space, carnival organization, the boundaries of social groups, aesthetic changes, and generally the balance of conformism and transgression.

Like most topics of social science research, carnival provides material for the

  just concentrating on the open manifestations of political opinions (like political calypsos in Trinidad 19 , or the images and texts of Fasnacht lanterns in Basel, Switzerland), 20 although they indeed have to be taken into account. To try and explore the relationships between carnival and politics, I would like first to come back to the general problem of defining carnival, and then to assess how power is present in carnival; I shall in the end present a few methodological suggestions for the study of politics in carnivals. 16 Alain Corbin, "Préface" in Alain Corbin, Noëlle Gérôme, Danielle Tartakowsky (dir.), Les usages politiques des fêtes aux XIX e -XX e siècles, Paris, Publications de la Sorbonne, 1994, p. 8.

  Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm 13 Port of Spain (Trinidad), 1989. The mask gives the reveler a chance of looking like someone else.

40A

  mask changes the person, it causes the reveler to become another without reneging on his or her self, it engenders a combination of the self and of one or several other(s). The coexistence of various masks, of different troupes, and of separate functions (the musicians sometimes form a specific sub-group, as in Limoux, into a forum where various combinations of self/other meet, interact and mix. The boundaries of social groups may, under certain circumstances, disappear; the foreigners or outsiders are given a place and a role in the community 43 .

  economic, social, religious or political) play in the organization of carnivals. A large gamut of possibilities appear here: tolerance or restrictions and suppression; autonomy of carnival groupings, clientelism and control by external forces; organization of carnival by national or local governments, under their close supervision, or in co-operation with them 47 . On the other hand, carnival offers an opportunity for assessing how citizens construe their relationship with power. Carnival may accommodate open manifestations of support or defiance towards governments: in the recent past Trinidadian and Haitian carnivals provided

  Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm 22

  observer's interpretation, in this case his or her own reconstruction of what are assumed to be widely shared representations of power in the society under investigation. Using nondirective surveys can complement this interpretation. In the course of non-directive individual or group interviews, people belonging to the community involved in the carnival are given an opportunity to verbalize their feelings about the festival, and experience shows that most often they closely interweave considerations pertaining to the carnival proper with visions of the society they live in, hopes and dreams about their capacity to control their destiny, and the evolution of the world at large. The material collected in studies of carnival combining semiological analysis and non-directive surveys is unique: it retains all the nuances, ambivalences and contradictions that are usually impossible to express in ordinary speech, and even less in questionnaire surveys. It enables the observer to understand more accurately the inner visions people may have of the society they live in, and therefore why they behave in ways which are supposed to be strange, or at least not in line with what their rational interest is assumed to be.The discussion of relationships between carnival and politics and the methodological suggestions proposed in this paper have been drawn from my own research in Trinidad and in Cape Town, complemented by informal observation of several European carnivals and readings of articles and books on carnivals around the world. Both discussion and suggestions are therefore based on limited experience and knowledge; it is my hope that they can nevertheless contribute to a larger discussion and hopefully generate new research.

  Carnivals rarely instigate political change. French historian Yves-Marie Bercé considers that, in general, "festivals never go well with political tensions."8 Under close scrutiny, neither carnivals of the past nor contemporary carnivals appear to be just rites of inversion, even less so an expression or manifestation of revolt against power and social hierarchies. Historian Samuel Kinser is highly critical of theories likening carnivals to rebellions, and especially of interpretations suggested by Roberto Da Matta from his studies

	Trinidad was still born;	6 Haitian carnivals of the 1980s were certainly more effective in
	shaking the Duvalier dynasty: they contributed to chasing away Baby Doc in 1986.
	of Brazil.

7 9 "Da Matta sees Carnival in the usual manner as reversing the surface of everyday life in playful fantasy. Carnival, however, plays not only with the surface but with what the surface hides [...] Carnival's logic is totalizing, a both-and rather than either-or game [...] Inversion theory is not false, but it is falsifying because it neglects the dynamics that connect what Bakhtin calls ''debasement'' -or, in the case of Rex's [one of the central characters in New Orleans' Mardi Gras] parade, exaltation -with incorporation, the dream of ever more inclusive, total ways of feeling, desiring and acting." 10 Maria Isaura Pereira de Queiros has shown how, in Brazil, social hierarchies and 5 Bercé, op. cit., pp. 80-81. 6 Ivar Oxaal, Race and Revolutionary Consciousness, A Documentary Interpretation of the 1970 Black Power Revolt in Trinidad, Cambridge, Schenkman, 1971. 7 Gage Averill, "A Day for the Hunter, A Day for the Prey," Popular music and Power in Haiti, Chicago, The University of Chicago Press, 1997; "Dechoukaj en musique, la chute de la dictature haïtienne," Critique

internationale, 7, avril 2000, pp. 127-142.

  Carnival organization is usually no small business. There are often organizing bodies, in some cases informal, often registered as non profit organizations or even as commercial enterprises. It is important to know how these bodies or boards are formed, who participates in them, what the different functions are and who is in charge of what. In the perspective of a political analysis of carnival, regulations must be studied: is carnival the object of a specific law (like in Trinidad) or does it simply have to abide by ordinary rules governing public gatherings? The type of relationship carnival organizers and band leaders entertain with public authorities has to be investigated: are carnival groupings totally autonomous; are they independent but subsidized; what is the type of co-operation that takes place between carnival organizers and political forces and power; do officials have to appear at a particular juncture in the ceremonies (like the Mayor in Dunkirk or the Burgomaster in Binche)? or do they remain hidden; how is the carnival policed?Relationships with private organizations should also be taken into account : are bands or troupes supported by commercial sponsors, and are the names of the latter given exposure on a large scale? Are there any connections between carnival groupings and firms, tourism offices, civic organizations or political forces (parties, trade unions, etc.), or What could be called the "topic" of the carnival is obviously central to any interpretation. Some carnivals always stage the same troupes wearing the same costumes, and the proceedings do not change from year to year, or at least they have not changed in recent times: carnival has become a ritual. The type of costumes, the organization of the bands, the order of their appearance, etc. clearly convey representations of social order (including social hierarchies), of the role of power and of the interplay of identities. One of the most striking examples of a ritualized carnival is probably that of Binche in Belgium. All sorts of myths have been developed by local historians about Binche, explaining the particular role of the principal mask, the Gilles, by the evocation of an ancient priest or

	observer must choose which aspects of carnival seem most heavily loaded with symbolic
	meaning,	51 beginning with the organization: is it centralized or not, what type of hierarchy
	prevails, is there a leadership model? Names are important also: names given to different
	moments in the carnival, to various aspects, to the troupes	52 and those who hold particular
	roles within them. The structure and organization of the carnival may accommodate a
	representation of power that reproduces the one normally prevailing	53 or, on the contrary,
	provide an alternative model.
	gangs? shaman he supposedly embodies.	54 It is however unfortunate that no attempt seems to have
	been made to analyze the Gilles, and other masks appearing in the same festival, in social
	terms.
	Semiology
	The preceding paragraphs may look like a shopping list. In a way, this is exactly
	what they are: an attempt to list items that should not be forgotten when one decides to
	embark on a study of carnival. It is certainly not even exhaustive. But the point is that a
	global and detailed description of the festivities is necessary to develop an interpretation of
	the social and political meanings of carnival, because different aspects may carry different
	significations -various elements of social representations; therefore nuances or
	contradictions are more likely to be revealed if most aspects are included in the description.
	Once this is done, it becomes possible to proceed with a semiological analysis. The
	Questions de recherche / Research in question -n°2 -November 2001	23
	http://www.ceri-sciences-po.org/publica/qdr.htm

  mix during carnival. In other cases, troupes may bring together people coming from various classes. There are instances when carnivals are construed as celebrations reserved for locals, but outsiders or foreigners are given a specific and indispensable role. Displays of differences and processes of blending, definitions of insiders and outsiders -within a troupe or the carnival in general -offer clues to help uncover representations of identity and evolutions in feelings of belonging.

		62
	Transgression
	Finally, every manifestation of transgression, be it moral, sexual, social or political,
	indeed tells a lot about representations of power and order. Carnivals frequently generate
	heated discussions about good and bad taste, about decent behavior and limits to be
	imposed	63 .
	61 Michel Agier, op. cit.

61

Styles of performance

Aesthetics and styles of performance, and changes affecting them noticed over a period of time, provide indications regarding social change as a whole. They very often reveal conceptions of modernity and aspirations to participate in a world of modernity or to invent original, alternative modernities. When change is clearly spurred by foreign influences, they may also give interesting indications about identifications with other societies, imagined as more modern, more affluent, more prestigious, or freer.

The present text is a revised version of a paper presented at the World Conference on Carnival III, Port of Spain, Trinidad and Tobago, October

[20][21][22][23] 1999. I wish to thank the two anonymous reviewers who assessed it for "Research in Question" for their stimulating remarks and Ms. Cynthia Schoch for her assistance in the preparation of the English text.

Alain Faure, Paris-Carême-Prenant, du carnaval à Paris au 19ème siècle, 1800-1914, Paris, Hachette, 1978.

Yves-Marie Bercé, Fête et révolte, des mentalités populaires du XVI e au XVIII e siècle, Paris, Hachette, 1994, p. 65.

Emmanuel Le Roy Ladurie, Le carnaval de Romans, de la Chandeleur au mercredi desCendres, 1579-1580, Paris, Gallimard, 1979.

Samuel Kinser, Carnival, American Style, Mardi Gras at New Orleans and Mobile, Chicago, The University of ChicagoPress, 1990, p. xv.

Michel Agier, Anthropologie du carnaval, la ville, la fête et l'Afrique à Bahia, Marseille, Parenthèses, IRD, 2000, pp. 232-236.

The notion of "social representation" used in this paper is based on the works of psycho-sociologists as presented in: Denise Jodelet, "Les représentations sociales, regard sur la connaissance ordinaire," Sciences humaines,27, avril 1993, pp. 22-24; Denise Jodelet (dir.), Les représentations sociales, Paris, Presses universitaires de France, 1993; and Pierre Mannoni, Les représentations sociales, Paris, Presses universitaires de France, 1998.

Just as carnival cannot be reduced to an inversion ritual, carnival politics does not simply amount to "resistance"; see: Denis-Constant Martin, "Cherchez le peuple..., culture, populaire et politique,"Critique internationale, 7, printemps 2000, pp. 169-183.

Louis Regis, The Political Calypso, True Opposition in Trinidad and Tobago, 1962[START_REF] Revélard | Le carnaval traditionnel en Wallonie[END_REF], Gainesville, University Press of Florida, 1999.

Arnold Van Gennep, Le folklore français, du berceau à la tombe, cycles de Carnaval-Carême etde Pâques, Paris, Robert Laffont, 1998 [1943-1948], p.714.

Leona M.Anderson, Vasantsova, The Spring Festivals of India, Texts and Tradition, Delhi, D.K. Printworld, 1993.

See: Marc Augé, "Préface" in PierGiovanni d'Ayala, Martine Boiteux (dir.), op. cit.,

Allen Roberts, "Symbolism: overview," in John Middleton (ed.), Encyclopedia of Africa South of theSahara, vol. 4, New York, Charles Scribner, 1998, pp. 192-197.

Denis-Constant Martin, "The burden of the name: Classifications and constructions of identity, the case of the ''coloureds'' in Cape Town (South Africa)," AfricanPhilosophy, 13 (2), 2000, pp. 99-124.

This dimension is thoroughly explored in Gage Averill's book on carnival in Haiti (op. cit.).

The broadcasting of "smutty calypsoes" on the radio is a permanent discussion in Trinidad: humorous political comment is expected, but is it acceptable to use obscene language when talking about the Prime Minister?

Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm 25

In general, all that participates in the construction of a carnival performance should be used as material for a semiological analysis: speeches, song lyrics, printed texts; 55 music sung or played by instrumental ensembles; dances and body languages; finally, time and space.

Basel, 1994. Zeedel …

Once "signifying signs" (or semes) have been identified and collected, they can be analytically organized to compose the basic material on which a symbolic analysis can be based. At this stage, deciphering symbols in order to reconstruct social representations is the task of the analyst, and is always a work of "cultured intuition." Interpretation derives from an implicit comparison, it uses the knowledge one may possess of various symbolic codes discovered in other societies to try and understand symbols noted in the course of the Symbolic codes vary from one society to another, although it seems that a few symbols -like the motion of throwing, or masks, on a broader level -are widespread and may be encountered in festivals taking place in distant and unconnected places. It follows that it is impossible to provide a universal guide for symbolic interpretation. However, in order to produce a socio-political interpretation of carnival, a limited number of symbolic fields can be investigated: they constitute domains where, given the connections between carnival and power, elements of social representations are likely to be more accessible.

Time

Carnivals are recurring festivals organized as a cycle (a structured succession of events) connected to other cycles. 58 They give social life a particular rhythm. Recurrence facilitates the apprehension of change although it often conveys an affirmation of duration and permanence, especially in societies where the majority of revelers belong to social groups whose civil rights have been denied, implying that they have no history. 59 More generally, the progression of events within the carnival cycle and the way the cycle ends to 56 Georges Balandier, Sens et puissance, les dynamiques sociales, Paris, Presses universitaires de France, 1971.

57 Samuel Kinser's analysis of carnivals in New Orleans and Mobile (op. cit.) offers a good illustration of how historical culture, anthropological knowledge and imagination can be combined.

58 Arnold Van Gennep, op. cit.; Claude Gaignebet, Marie-Claude Florentin, op. cit.

59 Carnival assumes this signification in most places which have experienced slavery and its consequences in terms of racism and scorn directed against the descendants of slaves; this is particularly evident in Cape Town.

Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm

Surveys

When symbolic elements have been identified and symbolic codes deciphered, when symbolic fields have been investigated and elements of social representations assembled, the observer is in position to propose her or his own interpretation of the carnival under study in order to offer an original analysis of the way people understand and appreciate the power system in which they live, how they position themselves in it, and even possibly how they envision their own capacity to act towards its preservation or transformation.

The observer's interpretation should ideally be complemented by a survey using nondirective methods to validate or invalidate the observer's findings and, above all, bring additional material regarding representations into the analysis. Social representations being a form of knowledge which is not spontaneously verbalized, they can be reconstructed from the observations of social manifestations in which several means of expression are combined, such as carnivals, and from the analysis of symbolic codes which are then used.

Sociologists and psycho-sociologists also create situations where social representations are at least partially verbalized: in individual or group interviews (focus groups).

Interviewees should be selected among people who feel something about the carnival and who have something to say about it, whether positive or negative. They need not necessarily be participants, although there must be revelers among the interviewees.

Qualitative research is based on a small number of interviewees, the depth and length of the interview counterbalancing the limited number of persons involved. Statistical representativeness is not possible in this context; the sample should, however, be selected to include individuals from the main social groups involved in the event under study, that is, depending on the relevant criteria for the study, individuals chosen because of their age, gender, social class, education, profession, wealth, religion, origin, etc.

Given the elusive character of social representations, it is indispensable to use nondirective methods, that is, to let interviewees speak as freely as possible and not interfere with the orientation of their discourse. Group interviews are generally more rewarding. The interview situation is indeed created by the researcher who has also recruited the Questions de recherche / Research in question -n°2 -November 2001 http://www.ceri-sciences-po.org/publica/qdr.htm


Sondes Abderrazek

Corinne Fredouille

Alain Ghio

Muriel Lalain

Christine Meunier

Virginie Woisard

Towards Interpreting Deep Learning Models to Understand Loss of Speech Intelligibility in Speech Disorders -Step 2: Contribution of the emergence of phonetic traits

Keywords: Deep learning, Interpretability, Phonetic traits, Intelligibility, Head and Neck Cancer, Speech disorders

published or not. The documents may come

INTRODUCTION

There is a common agreement that deep learning has achieved impressive performance in several tasks. Their growing popularity has aroused interest in how these widely used tools really work and has given rise to a new line of research dedicated to their analysis. Interpretability becomes even more important when Deep Neural Networks (DNNs) are applied in a domain as medicine where transparency is crucial and errors cannot be tolerated. In such a case, understanding the nature of encoded representation performed by the model is a way to guarantee its reliability. In this context, several approaches have been proposed to get insights into the internal functioning of these models. The most straight-forward interpretation technique is based on the analysis of neuronal responses to a representative input sample. To this end, selectivity property of individual units has been of particular interest to researchers. Among works we can find those relying on the whole activation of neuron as the phone selectivity index attributed by [START_REF] Nagamine | Exploring how deep neural networks form phonemic categories[END_REF] to units of an MLP trained for phone recognition task, while [START_REF] Rafegas | Understanding trained CNNs by indexing neuron selectivity[END_REF] and [START_REF] Zeiler | Visualizing and understanding convolutional networks[END_REF] characterized the selectivity of individual units through properties of samples maximizing their activation. Of relevance to the present work, several studies revealed that human-interpretable concepts can emerge without explicitly constraining the deep neural network to do it. Notably, [START_REF] Zhou | Object detectors emerge in deep scene CNNs[END_REF] and [START_REF] Bau | Understanding the role of individual units in a deep neural network[END_REF] were able to discover automatically meaningful object detectors in their CNN trained for scene classification. As well, in [START_REF] Gonzalez-Garcia | Do semantic parts emerge in convolutional neural networks?[END_REF], authors have shown that semantic part detectors emerge in object classifiers. While [START_REF] Zhou | Interpreting deep visual representations via network dissection[END_REF] introduced a more general method for interpretability, called Network Dissection, measuring the alignment between convolutional units and visual interpretable concepts. Most of the work reported above are interested in interpreting CNNs applied in computer vision domain. Even though CNNs have proven to be well suited for other tasks beyond computer vision such as speech signal processing, providing knowledge of how this input feature space is transformed into gradually higher levels of representation is still a challenging task due to the complex nature of speech signal, characterized within acoustic features.

The work presented here is part of a long-term project which aims to determine the linguistic units that contribute most to the maintenance or loss of the intelligibility in speech disorders. Different steps have been identified to reach this objective : (1) Modeling the characteristics of phonemic units of "normal" speech thanks to deep learning based system dedicated to a basic task of phone classification, (2) investigating the representational properties of the model in terms of phonetic contents, (3) the transfer of this deep learning modeling into a prediction task of intelligibility typically in the context of normal and disordered speech and the study of its capacity in yielding reasonable interpretation of the phonemic unit contribution in speech intelligibility and its variation (improvement or alteration). In a previous work [START_REF] Abderrazek | Towards interpreting deep learning models to understand loss of speech intelligibility in speech disorders, step 1 : CNN model-based phone classification[END_REF], we proposed a CNN-based architecture, trained on healthy speech for French phone classification task, to respond partly to the first step of that project. In this context, the encoding capability of the CNN-based model for the targeted task was demonstrated through very high correlation rates between its phone classification rates and the perceptual measures available for both patients and control speakers present in the disordered speech corpus involved.

In this paper, the main contribution is to show that phonetic feature detectors emerge in the fully connected layers of the CNN-based architecture mentioned above. To this end, an original framework based on neuronal activity was proposed in order to identify the set of interpretable neurons giving rise to such information on normal speech. This framework involves a vector representation of neuronal activity of units belonging to classification layers, coupled with a scoring approach enabling to highlight the capacity of neurons to detect specific phonetic features characterizing French phones. Exposed to speech recordings produced by patients suffering from speech disorders, the aim of this framework is to reveal a degraded behavior of the identified set of neurons and the loss of some specific phonetic traits in those patients, in different manner according to their speech impairment and level of speech intelligibility.

CORPUS AND PHONETIC FEATURES

As mentioned in the introduction, the search of neurons giving rise to phonetic features through the CNN model was carried out on normal/healthy speech. In this purpose, the BREF corpus was involved. This corpus was also used to train the CNN architecture described in the next section, on which this work relies. The BREF corpus is composed of French read-speech records produced by 120 male and female speakers, while reading texts from newspapers [START_REF] Lamel | BREF, a large vocabulary spoken corpus for french[END_REF], leading to about 115h of speech. All the speech productions were aligned automatically by using a forced-alignment system, commonly based on a Viterbi algorithm and three-state context-independent Hidden Markov Models (HMM) trained on separate French speech data. Thus, temporal boundaries of phones in speech records are available.

The C2SI-LEC corpus is a sub-part of the French speech corpus recorded within the C2SI project between 2015 and 2017 [START_REF] Astesano | Carcinologic Speech Severity Index Project: A Database of Speech Disorders Productions to Assess Quality of Life Related to Speech After Cancer[END_REF]. The overall corpus includes patients with Head and Neck Cancers (oral cavity or oropharynx) and control speakers. All patients underwent dedicated treatment consisting of surgery, and/or radiation therapy, and/or chemotherapy. During the recording protocol, all speakers were asked to record different speech production tasks (sustained /a/ vowels, isolated pseudo-words, text or sentences reading, image description and brief interviews to get spontaneous speech). Different perceptual evaluations were conducted by a jury of 5 to 6 experts (clinicians or speech therapists) including notably measures of speech severity (LEC-Sev) and intelligibility (LEC-Intel), on a 0-10 scale (0 -major speech disorder; 10 -no speech disorder) from the text reading task, and measures of phonemic alteration (DES-Phon) on a 0-3 scale (0 -no disorder; 3 -major disorders) from the image description task. Ratings given by the experts are averaged to provide unique values per speaker for the different perceptual evaluations. In this study, the focus is made on the reading task only, considering 89 speech records produced by 82 patients (7 patients were recorded twice) and 25 records for 24 control speakers (a control speaker was recorded twice). Based on the reading text (systematically corrected in case of reading errors), all the speech productions were aligned automatically, in a similar way as described for the BREF corpus.

Phonetic Features of French Phones

French phones can be characterized within a set of phonetic features that distinguish them. Different categorizations exist to define this set. In this paper, we adopted the approach described in [START_REF] Ghio | How to Compare Automatically Two Phonological Strings: Application to Intelligibility Measurement in the Case of Atypical Speech[END_REF] to characterize the French phones in terms of phonetic traits. Here, the notion of phonetic traits imposes a binary status (i.e. equals 1 if phonetic trait is present in the phone or 0 if absent). In order to define phonetic traits in a way they are phonetically and acoustically pertinent, a distinction between vowels and consonants was done as in [START_REF] Ghio | Achile : un dispositif de décodage acousticophonétique et d'identification lexicale indépendant du locuteur à partir de modules mixtes[END_REF]. In this context, the following phonetic traits will be considered : nasal, back, high, round, open for vowels and sonorant, continuant, nasal, voiced, compact, acute for consonants. Following the same logic, we investigated later the capacity of the hidden neurons to detect phonetic traits in separate spaces for vowels and consonants. This will be detailed on the upcoming section.

FRAMEWORK DESCRIPTION

The fundamental goal of this work is to understand the nature of information encoding at various stages of our CNN detailed in 3.1 and the way in which its neural representations shape the final task of phone classification and, simultaneously, are able to emerge specific phonetic traits. As reported in the state of the art, the most straight forward interpretation approach is to investigate the neuron responses. As we go deeper in the layers of the neural network, ob-serving the organization and structure of the activation space in response to specific inputs is a way to characterize how the learned representations evolve along the hierarchically structured layers.

Model Architecture

The CNN architecture used in this study was detailed in our previous work [START_REF] Abderrazek | Towards interpreting deep learning models to understand loss of speech intelligibility in speech disorders, step 1 : CNN model-based phone classification[END_REF]. It is recalled that the CNN inputs consist of a sliding context window of 11 successive acoustic frames, each having 40 log Mel-filter bank energy features along with their first and second derivatives. These features were computed on a 20ms window with an overlap of 10ms between two adjacent frames and served as an input to the CNN. Inspired by [START_REF] Pellegrini | Inferring phonemic classes from CNN activation maps using clustering techniques[END_REF], the CNN consists of two pairs of convolution and max-pooling layers followed by three fully connected layers of 1024 neurons, with a ReLU activation function. Finally, a softmax layer corresponds to the posterior probability of each class associated with 31 French phones and silence. It should be mentioned that the three fully connected layers, denoted FC1, FC2, and FC3 in the rest of the paper, will be the focus of the neuronal activity based framework proposed in next sections.

One key factor of a reliable interpretation is the selection of data used to ensure this task. Ideally, our CNN could be fully characterized if all possible input patterns could be presented, i.e. frames issued from the different French phones produced in all possible contexts, then neural responses measured for each of these inputs. It is obvious that in practice, the adopted BREF corpus does not cover all these possibilities, having to meet the need for training, validation and interpretation of the model. However, we tend to build the richest interpretation dataset possible covering the 31 French phones studied here, which the CNN was trained on for classification purpose. For this reason, we did not proceed to a random choice of frames for the interpretation set. Rather, we considered all the frames associated with speech segments (yielded by the automatic forced alignment) related to a complete phone production as well as involving different phone contexts and all the speakers available in the corpus. In addition to the diversity of the frames, the dataset was balanced in order to achieve a roughly equal distribution of frames over the 31 phones. Thus, the generated dataset used for interpretation purpose (different from datasets used for CNN training and validation), named BREF-Int, includes almost 85K of frames, and resulted in a classification accuracy of 80.8% once fed to the trained CNN. We already evoked in our previous work that our model is able to generalize to new data since it reached 74% accuracy when evaluated on healthy control utterances of the C2SI-LEC corpus described in section 2.

Representation Vectors of Neurons

In order to represent a neuron, the CNN is fed with the BREF-Int dataset and the activation hn,i of the neuron n is extracted, given the i th input frame. A normalized activation an,i is then calculated for each neuron by dividing the activation values of the neuron for different input frames of the dataset by the maximum of these values reached by the same neuron over all the samples; an,i =

h n,i hmax,n
where hmax,n = max hn,j∀j. Afterwards, a process to generate representation vectors reflecting the neuronal activity was set up. An illustration of the steps we passed through is shown in fig. 1. For a neuron n, a histogram is generated for each phone k in order to approximate the distribution of the neuron activations as response to all the frames associated with k. The histogram displays the number of frames falling into each interval of normalized activation, also called bins, which have equal width and divide the entire range of normalized activation [0; 1]. In our case, we fixed the number of bins to 20. Subsequently, a vec-Fig. 1: Process of representation vector generation for a neuron tor V n,k ∈ N 20 containing the number of frames appearing in each bin is derived from each histogram. Finally, a concatenation of these vectors generated for each of the 31 phones for a given neuron results in a 620-dimensional representation vector, and is considered later as characterizing the neuron n for interpretation purpose. Interesting insights about the organization of neurons per layer and the emergence of interpretable ones, in regards with phonetic traits, will be revealed in next sections.

Capacity of Neurons to detect Phonetic Traits

In order to align each neuron with the phonetic traits mentioned in section 2 and to measure the hidden unit encoding degree for each of these features, a score has to be defined. The aim of this score is to quantify the degree to which a unit detects the presence of a phonetic trait based on the activation of phones associated with, and complementary those which do not present this phonetic trait. To this end, the analysis was still based on the values of normalized activations for the individual units as a response to the dataset, already presented in the previous section.

For each neuron n, let A k,n be the normalized activation values of n for all the frame samples belonging to the phone k. We note the median activation value of the neuron n for the phone k as mA k,n . The score Sn,T x , quantifying the degree to which a unit detects the presence of a phonetic trait, is therefore calculated for each neuron n and phonetic trait Tx as follows:

Sn,T x = 1 |Tx| k∈Tx mA k,n - 1 | Tx| k∈ Tx mA k,n (1)
where x ∈ [v, c] denotes the macro-class of either vowels or consonants, respectively v and c. Consequently, Tv denotes a vowel phonetic trait where: Tv ∈ {nasal, back, high, round, open} and Tc denotes a consonant phonetic trait where: Tc ∈ {sonorant, continuant, nasal, voiced, compact, acute}. It has to be noted that since phonetic traits are binary concepts characterizing separately vowels and consonants, the score is calculated, consequently, taking into account either vowels or consonants. It is important to mention that the score Sn,T x ∈ [-1; 1]. Therefore, a strong value close to 1 reflects the fact that the neuron is a strong detector for the phonetic trait in question since it distinguished by a high activation level the phones presenting the features. At the same time, a very low activation level represents the complementary set of phones not presenting this feature. Conversely, when a neuron has a very low score close to -1, it means that the neuron is a strong detector for the non phonetic trait, which is relevant as well. Now once we have a score reflecting how well a neuron encodes a given phonetic trait, we consider that the neuron n is a detector of the phonetic trait Tx if Sn,T x exceeds a threshold. And conversely, if Sn,T x is below the threshold, then the neuron n is considered as detector of the absence of phonetic trait Tx. Clearly, different thresholds could lead to different numbers of neurons selected as phonetic trait detectors across layers. However, we observe that it does not result in a significant change in term of the distribution of this set of neurons over the different phonetic traits. Thus, we have empirically fixed the threshold to value ±0.25.

Given that a neuron can be a detector for several phonetic traits (associated with relevant scores respecting the threshold), the top phonetic trait is chosen in this case. If the neuron is identified as detector for multiple phonetic features belonging to both vowel and consonant macro-classes, it will be considered as detector for the top phonetic trait for both vowels and consonants.

RESULTS

Emergence of phonetic features

As we previously detailed, a set of 620-dimensional vectors extracting the hidden representations of neurons was prepared. A projection of these representation vectors into a 2-dimensional space was performed by t-Distributed Stochastic Neighbour Embedding (t-SNE) [START_REF] Van Der Maaten | Viualizing data using t-sne[END_REF] for each layer. Since t-SNE applies a non-linear dimensionality reduction technique where the focus is on keeping the very similar data points close together in lower-dimensional space, we expect to have a visualization where neurons with similar encoding properties appear in clusters. The first aim at this stage is to explore to what decomposition the hidden layers converged to ensure the final task of phone classification. The second aim is to determine if clusters of neurons associated with a specific phonetic trait (according to the score we defined) can be highlighted. Since our focus is basically to analyze neurons with phonetic feature encoding properties, only identified neurons respecting the fixed threshold will be displayed in the following t-SNE visualization plots. Thus, a specific color is attributed to each neuron according to the phonetic trait it detects based on its score. Fig. 2 illustrates the neurons considered as detectors for the consonant phonetic traits. This visualization reveals impressive insights Firstly, the absence of FC1 visualization in the plot is due to the fact that none of its neurons were identified as a phonetic trait detector, neither for vowels nor for consonants. On the other hand, the number of phonetic trait detectors increases by a factor of close to two when we go deeper in layers towards the final layer performing phone classification. Indeed, although FC2 and FC3 have the same number of hidden neurons (1024), the total number of neurons detecting consonant phonetic traits has increased from 206 detectors in FC2 to 373 in FC3. This emergence of phonetic trait detectors when going deeper in layers suggests these features allow discrimination among phone classes. In fig. 2, we can observe the presence of dense neuron clusters automatically identified as encoding the same phonetic trait. To analyze in more details, fig. 2(b) and fig. 2(d) show the sorted count of neurons detecting consonant phonetic traits in FC2 and FC3 respectively. We observe that neurons detecting the nasality trait have the strongest presence in both layers. A similar study was performed on the vowel phonetic traits and generated roughly the same patterns. These results suggest that phonetic trait detection is an important part of the representation built by the CNN to obtain discriminative information for the final task of phone classification.

Application to disordered speech

As specified in the previous section, BREF-Int dataset issued from the BREF corpus was used to fix the set of interpretable neurons in each layer, that we considered as emerging phonetic features. Let XBREF,L,x be this set of neurons for the layer L and the macro-class x. In this section, we want to examine to which extent we can rely on this set of neurons to extract relevant interpretations about the speech alteration by injecting disordered speech.

To do so, each individual recording per speaker (involving controls and patients) available in C2SI-LEC corpus is injected in the CNN following the same process described in section 3. This permits to define the set of neurons having a score that exceeds the predefined threshold fixed on the BREF-Int dataset. It is important to note that even though we are no more dealing with balanced data in terms of number of samples per phone, we assume that the proposed score is relatively robust when exposed to highly imbalanced data (C2SI-LEC recordings) since it is based on the median calculus per phone distribution which is less sensitive to outliers than the mean. Once the set of neurons being selected for the corresponding speaker spk, noted X spk,L,x , it will be compared to the corresponding set of interpretable neurons issued from the BREF-Int dataset. This comparison is based on the Sørensen-Dice index, noted SDI, used to measure the similarity between two sets of data. In our case, for a given layer L, macro-class x and C2SI-LEC speaker spk:

SDI spk,L,x = 2|X spk,L,x ∩ XBREF,L,x| |X spk,L,x | + |XBREF,L,x| (2)
Ranging between 0 and 1, a strong value of SDI spk close to 1 reflects that the two sets of neurons X spk and XBREF are almost equal. Precisely, the evoked neural responses of the set of interpretable neurons to the C2SI-LEC speaker were as strongly selective for phonetic features as they were for the same ones on the BREF-Int dataset. In other words, this means that the speech production of C2SI-LEC speaker in question presents acoustic characteristics close to BREF healthy speakers in terms of phonetic feature production (which is supposed to be the case for most of control speakers). While a low score close to 0 means that the two sets of neurons X spk and XBREF are almost disjoint. This implies that almost none of the phonetic feature detectors has expressly provided a selective response for a phonetic feature when exposed to the C2SI-LEC speaker spk. Consequently, we can assume that the speech production of the speaker in question does not exhibit typical acoustic characteristics. To confirm this assumption, Pearson correlation coefficients, noted r, were calculated between SDI and each of the perceptual measures for the overall set of C2SI speakers. Table 1 is a sum-up of the obtained correlations per layer and macro-class of either vowels or consonants. Firstly, it can be mentioned that these correlation rates are rather coherent with those reached in [START_REF] Abderrazek | Towards interpreting deep learning models to understand loss of speech intelligibility in speech disorders, step 1 : CNN model-based phone classification[END_REF] and reported in Table 1 (CNN accuracy for the phone classification task). Secondly, SDI scores issued from FC3 correlates better with the different perceptual measures than those from FC2. This reflects that the more we get close to the phone-level decisions, perceptual measures are better "represented". Correspondingly, this is consistent with conclusions raised in section 4.1, when observing the increase in number of interpretable neurons detecting phonetic features when going deeper in layers. This finding comes to strengthen that phonetic features contribute to the discrimination of phones, and will be therefore very interesting for the characterization of speech disorders and related to intelligibility loss.

CONCLUSION AND FURTHER WORK

In this paper, we argue that an interpretation involving phone-level decisions, as well as having access to more abstract level of representation as phonetic features, is of a great interest to go into the characteristics of disordered speech. Therefore, we propose a complete framework in order to analyze the role of dense layers and individual hidden units within a CNN model. The latter was trained for the task of French phone classification, but the proposed framework can be applied for other kinds of classification tasks or application domains. In our specific context, this framework reveals the presence of interpretable neurons detecting distinctive phonetic traits in the dense layers of the CNN while dealing with normal/healthy speech. Exposed to disordered speech (due to Head and Neck Cancers), we observed, based on strong correlations with perceptual evaluation of speech disorders by experts, that this set of phonetic trait detectors is less efficient while alterations in speech production increase. In further work, we will confront this loss of efficiency and related phonetic traits with the clinical information available per patient. Preliminary analyses show in particular that the distinction between some groups of patients according to the size of their tumors is possible within the proposed framework and, notably, the SDI scores. Finally, the sets of interpretable neurons, able to detect phonetic traits, will be at the core of the third step of our overall project, related to intelligibility.

ACKNOWLEDGMENT

This work has been carried out thanks to the French National Research Agency in RUGBI project untitled "Looking for Relevant linguistic Units to improve the intelliGiBIlity measurement of speech production disorders" (Grant n o ANR-18-CE45-0008-04).

Fig. 2 :

 2 Fig. 2: t-SNE visualization highlighting neurons with phonetic trait encoding properties for consonants: (a) & (c) Plots of the embedded neurons of layers FC2 and FC3. (b) & (d) Sorted counts of neurons in FC2 and FC3 detecting each of the consonant phonetic traits.

Table 1 :

 1 Correlation between Sørensen-Dice index and perceptual measures considering vowels or consonants and layers FC2 and FC3.

			LEC-Sev LEC-Intel DES-Phon
	CNN Accuracy	0.91	0.78	-0.88
	FC2	Vowels Consonants	0.82 0.85	0.66 0.75	-0.76 -0.78
	FC3	Vowels Consonants	0.84 0.88	0.73 0.78	-0.79 -0.82