Yohann Dabi
email: yohann.dabi@gmail.com

Arnaud Fauconnier

Christine Rousset-Jablonski

Arounie Tavenet

Anne-Cécile Pizzofferrato

Xavier Deffieux

Do women with suspected endometriosis benefit from pelvic examination to improve diagnostic and management strategy?

Keywords: Endometriosis, Pelvic Examination, Symptoms, Diagnostic

Objective:

To analyze the literature and expose best evidence available regarding the benefit of pelvic examination for women with suspected endometriosis Methods: the AGREE II and GRADE systems for grading scientific evidence.

Results:

Endometriosis is characterized by the heterogeneity in its clinical presentation with many different symptoms reported by patients. In the literature, questioning for each symptom has a high sensitivity, reaching 76-98%, but lacks specificity (20 -58%). The symptom-based approach is limited by its low specificity, the absence of external validation for most of the models developed and the inability to characterize the extent of the disease, which could have major implications in the decision -making process. The latest systematic review and meta-analysis included a total of 30 studies with 4,565 participants, compared the diagnostic performance of several modalities for endometriosis. Physical examination had a pooled sensitivity of 71% and a specificity of 69%, with an average diagnostic accuracy of 0.76. Overall, the value of pelvic examination is conferred by its high positive likehood ratio and specificity. Besides its dia nostic alue, el ic exa ination i ro es atients' management by allowing the identification of a possible myofascial syndrome as a differential diagnosis. It also increases the quality of the preoperative workup and influences the quality of surgical excision and decreases the time to diagnosis.

Conclusion:

Despite the lack of studies in the primary care context, pelvic examination (vaginal speculum and digital vaginal examination) increases the diagnostic value for suspected endometriosis in association with questioning for symptoms.

Introduction

Recent international guidelines have modified gynecological follow-up in asymptomatic women by limiting the indications for pelvic examination [START_REF] Us Preventive | Screening for Gynecologic Conditions With Pelvic Examination: US Preventive Services Task Force Recommendation Statement[END_REF]. Systematic follow-up consisted of symptom questioning and pelvic examination including vulvar inspection, speculum vaginal examination, and digital vaginal examination. Studies have reported that these medical examinations can be stressful and are perceived as intrusive with negative experiences [START_REF] Yilmaz | The relationship between body privacy and anxiety in women having gynecological examination[END_REF]. However, when symptomatic, most women will accept pelvic examination if required for diagnosis purpose and if the procedure is performed by a qualified health professional [START_REF] Carugno | Impact of using words with unpleasant emotional connotations on perceived patient discomfort during vaginal speculum examinations: A randomized controlled trial[END_REF].

Endometriosis, particularly in its advanced stages, is a well-known cause of disabling pelvic pain and infertility [START_REF] Gordts | Pathogenesis of deep endometriosis[END_REF]. It is estimated that up to 10% of women of reproductive age and 50% of infertile women have a huge impact on quality of life in some cases [START_REF] Eskenazi | Epidemiology of endometriosis[END_REF][START_REF] Meuleman | High prevalence of endometriosis in infertile women with normal ovulation and normospermic partners[END_REF]. In patients with chronic pelvic pain, 11 studies ranged the prevalence of endometriosis with great disparities between 2 and 74% [START_REF] Borghese | Definition, description, clinicopathological features, pathogenesis and natural history of endometriosis: CNGOF-HAS Endometriosis Guidelines[END_REF]. This disease represents a public health issue with considerable cost at both individual and society levels [START_REF] Soliman | Real-World Evaluation of Direct and Indirect Economic Burden Among Endometriosis Patients in the United States[END_REF].

Endometriosis diagnosis is a matter of concern. As diagnosis is often the gatekeeper to treatment, the faster the diagnosis, the sooner appropriate treatment can be introduced.

T e latest "state of t e art" re iew by Pascoal et al. perfectly underlines the diagnostic difficulties of this pathology and the imperfect nature of each method, with its strengths and weaknesses, from which the questioning and pelvic examination do not escape [START_REF] Pascoal | Strengths and limitations of diagnostic tools for endometriosis and relevance in diagnostic test accuracy research[END_REF]. Indeed, women can present with great disparities of non-specific symptoms and some of them are even completely asymptomatic (independently of the extent of anatomic lesions). Pelvic examination is currently part of first line diagnostic strategy in women with suspected endometriosis in both European and French HAS Guidelines [START_REF]ESHRE 38th Annual Meeting of ESHRE, ESHRE 2022 | Official Site[END_REF][START_REF] Collinet | Management of endometriosis: CNGOF/HAS clinical practice guidelines -Short version[END_REF]. Whenever possible, pelvic examination associated with the questioning is the first step of the diagnostic algorithm. Several authors reported a benefit of clinical examination to improve diagnostic strategy [START_REF] Agarwal | Clinical diagnosis of endometriosis: a call to action[END_REF]. The question of the benefit of pelvic examination in patients with suspected endometriosis is all the more relevant that it usually also aims to identify painful spots that could indicate endometriosis. The French college recently issued guidelines on the benefit of pelvic examination in various situations, in either gynecology or obstetrics [START_REF] Deffieux | Pelvic exam in gynecology and obstetrics: Guidelines for clinical practice[END_REF]. This examination must be carried out with particular caution, especially in the context of endometriosis because of its painful nature in these patients and women should be informed of the modalities and expectations prior consent to be examined.

The aim of this work was to analyze the literature and expose best evidence available regarding the benefit of pelvic examination for women with suspected endometriosis

Methods

In collaboration with the methodologist in charge of the aforementioned guidelines, a search strategy was designed using key terms and keywords. The search was limited to human studies written in English or in French. The PubMed platform was used to search MEDLINE. MeSH terms and non-MeSH terms were used. Search equations used "AND" and "OR" on MEDLINE/PubMed. Key words used for this PICO were: "endo etriosis"; "dee endo etriosis"; " a inal endo etriosis"; " el ic exa ination" ; " sical exa ination" ; "vaginal s eculu "; " a inal exa ination"; "i a in "; " "; " el ic ultrasound".

Each study was evaluated independently, and an overall level of evidence was processed once the review completed.

In this work, pelvic examinations referred to vulva inspection, speculum examination of the vagina and the cervix and palpation through manual examination of internal genital organs (vagina and cervix, uterus corpus, adnexa) and hypogastric region. The question of rectovaginal examination was not considered in these guidelines due to the limited data available in the literature.

Results

The main studies reporting on the relevance of physical examination for the diagnostic of endometriosis are reported in Table 1.

Value of the questioning for symptoms in the diagnostic strategy of patients with suspected endometriosis Elements of the systematic questioning in women with suspected endometriosis Many studies evaluated the relevance of the questioning for symptoms in women with suspected endometriosis. Painful symptoms of deep endometriosis have characteristics that distinguish them from pain of other origins [START_REF] Fauconnier | Endometriosis and pelvic pain: epidemiological evidence of the relationship and implications[END_REF]. These pains may be specific to the involvement of a precise anatomical location or a precise organ by the deep endometriosis implants [START_REF] Fauconnier | Relation between pain symptoms and the anatomic location of deep infiltrating endometriosis[END_REF]. A detailed clinical history should search for the most common symptoms and their severity, including gynecological symptoms on one side, such as dysmenorrhea [START_REF] Fauconnier | Endometriosis and pelvic pain: epidemiological evidence of the relationship and implications[END_REF],

cyclical and non-cyclical pelvic pain, deep dyspareunia (and impaired sexual function) [START_REF] Graaff | The significant effect of endometriosis on physical, mental and social wellbeing: results from an international cross-sectional survey[END_REF] and infertility, and non-gynecological cyclical symptoms on the other side, such as dyschezia [START_REF] Nnoaham | World 16 Endometriosis Research Foundation Women's Health Symptom Survey Consortium. Developing symptom-based predictive models of endometriosis as a clinical screening tool: results from a multicenter study[END_REF], dysuria [17], hematuria, flank pain, rectal bleeding [START_REF] Fauconnier | Relation between pain symptoms and the anatomic location of deep infiltrating endometriosis[END_REF] and shoulder pain [START_REF]ESHRE 38th Annual Meeting of ESHRE, ESHRE 2022 | Official Site[END_REF]. The visual analog scale (VAS) is a well-adapted tool for measuring pain in endometriosis [START_REF] Bourdel | Systematic review of endometriosis pain assessment: how to choose a scale?[END_REF].

Eventually, physicians should evaluate the potential overall reduction in the quality of life of patients with suspected endometriosis [START_REF] Marinho | Quality of Life in Women with Endometriosis: An Integrative Review[END_REF][START_REF] Gao | Health-related quality of life burden of women with endometriosis: a literature review[END_REF].

Performance of the questioning in women suspected with endometriosis Overall, questioning for each symptom has a high sensitivity, reaching 76-98%, but lacks specificity ( 20 -58%) as summarized by Pascoal et al. [START_REF] Eskenazi | Validation study of nonsurgical diagnosis of endometriosis[END_REF][START_REF] Nawrocka-Rutkowska | Evaluation of the Diagnostic Accuracy of the Interview and Physical Examination in the Diagnosis of Endometriosis as the Cause of Chronic Pelvic Pain[END_REF][START_REF] Pascoal | Strengths and limitations of diagnostic tools for endometriosis and relevance in diagnostic test accuracy research[END_REF]. In a literature review on chronic pelvic pain, Vercellini et al. discussed the frequent non -endometriotic causes, such as irritable bowel syndrome, myofascial syndrome, pelvic adhesions, pelvic venous congestion, and interstitial cystitis [START_REF] Vercellini | Chronic pelvic pain in women: etiology, pathogenesis and diagnostic approach[END_REF]. Several authors developed models with different Overall, the symptom-based approach is limited by its low specificity and the absence of external validation for most of the models developed. The "paradox" of the aforementioned models is that they were developed in expert centers but aim to increase the diagnostic performance in primary care. Future research could focus on testing their performance in primary care as well as refining their use to help prescribing MRI imaging or guide the patients toward specific pathways of care.

Another issue with this approach to diagnose endometriosis is its inability to characterize the extent of the disease, which could have major implications in the decision -making process.

Value of the pelvic examination in patients with suspected endometriosis

Elements and timing of pelvic examination in women with suspected endometriosis Studies report that between 15% and 30% of women with endometriosis have deep infiltrating disease [START_REF] Fauconnier | Endometriosis and pelvic pain: epidemiological evidence of the relationship and implications[END_REF]. Speculum examination may reveal bluish spot characteristic of endometriosis in the retrocervical area and the upper part of the posterior vaginal wall.

Vaginal digital examination in women with suspected endometriosis aims to identify deep posterior infiltration of the retrocervical area [START_REF] Dc | Retrocervical, retrovaginal pouch, and rectovaginal septum endometriosis[END_REF] i.e vaginal nodules vagina (figure 1), uterosacral ligaments, or pouch of Douglas; as well as adnexal masses [START_REF] Riazi | Clinical diagnosis of pelvic endometriosis: a scoping review[END_REF]. One may also palpate induration or nodularity in the anterior area which may be related to deep endometriosis of the bladder or uterine anterior serosa. The painful nature of palpated lesions is characteristic. Pelvic examination also allows the identification of a possible myofascial syndrome [START_REF] Kapurubandara | A systematic review of diagnostic tests to detect pelvic floor myofascial pain[END_REF]. Hypersensitivity phenomenon have been largely documented in women with endometriosis and the association with a myofascial syndrome is frequent, with around 60% of patients having both myofascial syndrome and endometriosis [START_REF] Margueritte | Assessment of neuropathic pain among women with suspected endometriosis based on two specific surveys[END_REF]. Allodynia, contact hyperpathia with tight clothing, and provoked vulvodynia should be tested as evidence of cutaneous and vulvar hypersensitivity [START_REF] Ploteau | New concepts on functional chronic pelvic and perineal pain: pathophysiology and multidisciplinary management[END_REF][START_REF] Jarrell | Allodynia and Dysmenorrhea[END_REF]. These patients often have hyperpathy or real trigger points found in the muscles of the perineum or the deep part of the buttocks [START_REF] Stratton | Association of chronic pelvic pain and endometriosis with signs of sensitization and myofascial pain[END_REF]. Vaginal digital examination can reveal painful tension in the bundles of the levator ani muscle and the pelvic portions of the internal obturator muscles. Painful tension of the piriformis muscles and the gluteal portions of the internal obturator muscles can be sought in the prone position. These pains may be indicative of a regional myofascial syndrome, but are often part of a diffuse pain with extra-pelvic trigger points suggestive of a central hypersensitivity syndrome such as fibromyalgia [START_REF] Clauw | The relationship between fibromyalgia and interstitial cystitis[END_REF]. These hypersensitization phenomena sustain the pain in patients with endometriosis and explain the persistence of certain pains after surgical management of endometriosis [START_REF] Riant | Predictive factors and prevention of chronic postoperative pelvic and perineal pain[END_REF]. The myofascial syndrome can also be a differential diagnostic in women with chronic pelvic pain, with no concurrent endometriosis. during a routine examination outside of menstruation [START_REF] Koninckx | Diagnosis of deep endometriosis by clinical examination during menstruation and plasma CA-125 concentration[END_REF]. This better diagnostic performance must be balanced against the discomfort of a pelvic examination during the menstrual period in some women.

As stated in the latest ESHRE guidelines [START_REF]ESHRE 38th Annual Meeting of ESHRE, ESHRE 2022 | Official Site[END_REF], vaginal examinations might be inappropriate in certain situations and in adolescents. Furthermore, it can be painful for some women. In these women, with high burden/discomfort (adolescents, due to religion, painful compared the diagnostic performance of several modalities for endometriosis [START_REF] Zhang | Comparison of physical examination, ultrasound techniques and magnetic resonance imaging for the diagnosis of deep infiltrating endometriosis: A systematic review and meta-analysis of diagnostic accuracy studies[END_REF]. Physical examination had a pooled sensitivity of 71% (95% CI, 60-80%) and a specificity of 69% (95% CI, 54-82%), with an average diagnostic accuracy of 0.76 (95% CI, 0.66-0.83).

Some studies evaluated the performance of models combining questioning symptoms and pelvic examination signs, increasing the performance of questioning alone Overall, the value of pelvic examination is conferred by its high positive likehood ratio and specificity. Its performance overpass these of questioning alone for diagnostic purpose.

The value of pelvic examination is always compared with that of ultrasound and MRI. The low negative predictive value of "routine" ultrasound for the diagnosis of deep endometriosis has been reported in several studies [START_REF] Bazot | Diagnostic accuracy of physical examination, transvaginal sonography, rectal endoscopic sonography, and magnetic resonance imaging to diagnose deep infiltrating endometriosis[END_REF][START_REF] Zhang | Comparison of physical examination, ultrasound techniques and magnetic resonance imaging for the diagnosis of deep infiltrating endometriosis: A systematic review and meta-analysis of diagnostic accuracy studies[END_REF][START_REF] Eskenazi | Validation study of nonsurgical diagnosis of endometriosis[END_REF]: it is relevant mainly for the diagnosis of endometrioma and cannot therefore replace clinical examination. Concerning the value of MRI, the great variability of the MRI protocols described in the literature and the absence of standardized reports limit the reproducibility of this examination in this indication [START_REF] Pascoal | Strengths and limitations of diagnostic tools for endometriosis and relevance in diagnostic test accuracy research[END_REF]. In addition, the expertise of the radiologist and the location of the lesions (lower agreement for determining damage to the utero sacral ligaments) have an influence on the performance of MRI [START_REF] Saba | Diagnostic confidence analysis in the magnetic resonance imaging of ovarian and deep endometriosis: comparison with surgical results[END_REF][START_REF] Jaramillo-Cardoso | Pelvic MRI in the diagnosis and staging of pelvic endometriosis: added value of structured reporting and expertise[END_REF]. No study has evaluated the sensitivity and specificity of pelvic MRI for the diagnosis of endometriosis without prior clinical examination.

Other benefits of the pelvic examination for the management It is well established that the quality of the preoperative workup influences the quality of surgical excision and minimizes the risk of incomplete excision or an unplanned procedure [START_REF] Leonardi | When to Do Surgery and When Not to Do Surgery for Endometriosis: A Systematic Review and Metaanalysis[END_REF]. Soliman et al 2017 showed that clinical diagnosis (non-invasive) also decreases the time to diagnosis [START_REF] Soliman | Factors Associated with Time to Endometriosis Diagnosis in the United States[END_REF]. Similar conclusions were drawn from the recent review by Agarwal et al 2019 in the American Journal of Obstetrics and Gynecology (AJOG) [START_REF] Agarwal | Clinical diagnosis of endometriosis: a call to action[END_REF].

Limits

Some bias in the available literature deserves to be underlined, as it could influence the magnitude of the benefit of both medical questioning and pelvic examination. Most published data concern expert centers and clinicians with great experience in diagnosing endometriosis, with an increased prevalence among patients tested when compared to the general population [START_REF] Fauconnier | Epidemiology and diagnosis strategy: CNGOF-HAS Endometriosis Guidelines[END_REF].

There is also probably a bias linked to the duration of the evolution of symptoms at the time of the consultation and a verification bias inherent in the pathology (the comparator used is always laparoscopy; therefore, only patients with an indication for surgery have formal confirmation of the diagnosis).

Furthermore, as underlined in the latest recommendations of the CNGOF -HAS 2018 [START_REF] Fauconnier | Epidemiology and diagnosis strategy: CNGOF-HAS Endometriosis Guidelines[END_REF], there are no data from the 1st line clinical examination for the diagnosis of deep endometriosis (primary care) since all the studies relate to the performance of examinations by expert -clinicians or highly experienced. In addition, studies are often conducted in "expert" centers, where the prevalence of the disease is probably higher than in the general population. Therefore, it is possible that the diagnostic relevance of clinical examination is overestimated in light of the literature. Eventually, it is possible that the performances of both physical examination and questioning are biased since only patients exhibiting a positive screening test (i.e., intense symptoms and / or positive physical examination) with undergo a laparoscopy to confirm the diagnostic in case of negative or indeterminate imaging. This bias could be responsible for an increased sensitivity and decreased specificity.

Another point is that of the bias associated with the duration of the evolution of symptoms at the time of the consultation, which may have implications for the findings of the clinical examination and history and modify their relevance. Finally, there is a verification bias inherent in the pathology and valid for all the studies included; the comparator used is always laparoscopy + / -histological analysis; therefore, only patients with an indication for surgery have formal confirmation (if possible) of the diagnosis.

To date, no study has evaluated the diagnostic relevance of history alone compared with pelvic examination alone. No study has assessed the diagnostic relevance of history alone compared with the combination of history and pelvic examination.

Conclusion

In women with suspected endometriosis, pelvic examination (vaginal speculum and digital vaginal examination) when positive increases the diagnostic value in association with questioning for symptoms. Informing patients on the usefulness of this examination will allow its realization within the framework of an empathetic relationship.

  symptoms to predict the presence of endometriosis. Chapron et al. recently[START_REF] Chapron | A new validated screening method for endometriosis diagnosis based on patient questionnaires[END_REF] identified eight interrogation elements and proposed several diagnostic thresholds for their score: etween and ≥ 5: (i) i l s ecific, correctl identif in atients wit out t e disease; (ii) highly sensitive, identifying the patients with the disease; and (iii) a level maximizing sensitivity and specificity for the best classification of the whole population. They reported the following performance of their model: score 1: specificity of 91% (95% CI [89-93]); score < 11: sensitivity of 91% (95% CI [89-93]); score ≥ 8: s ecificit of 75% (95% CI [72-78]), and sensitivity of 73% (95% CI [70-76]). Fauconnier et al. reported a standardized selfquestionnaire developed from the patients' verbatim (built specifically for diagnosis) with 21-item yes/no questions about painful symptoms [26]. They included 105 cases and 197 controls, and the full question set prediction model, including age, had an area under the receiver operating characteristic curve of 0.92 (95% confidence interval, 0.87-0.95) after internal validation. The high-risk classification rule had a specificity of 98.0% and a positive likelihood ratio of 30.5. The low-risk classification rule had a sensitivity of 98.1% and negative likelihood ratio of 0.03. Eventually, Bendifallah et al. investigated the use of machine learning algorithms (MLA) in the diagnosis and screening of endometriosis based on 16 key clinical and patient-based symptom features [27]. In their work, the sensitivity, specificity, F1-score, and AUCs of the MLA to diagnose endometriosis in the training cohort from the Ziwig Health Platform were 0.82 to 1, 0-0.8, 0-0.88, 0.5-0.89. They performed validation on a 100 -patients prospective cohort with similar performance.

Figure 1 :

 1 Figure 1: bluish endometriosis spots of the posterior vaginal cul de sac

  models. The study by Chattot et al. established a predictive score for recto sigmoidal involvement comprising 4 parameters including a questioning component (the presence of blood in the stool at the time of menstruation) and a clinical examination component (palpation of a nodule on vaginal touch) [41]. Eskenazi et al. included 90 women with a scheduled laparoscopy or laparotomy [21]. Ultrasound and examination best predicted ovarian endometriosis, correctly classifying 100% of cases with no false positive diagnoses in the study sample.

Table 1 .

 1 The larger cohorts are those of Hudelist et al. reporting on 129 women 50%, 3.88, and 0.57, for vaginal endometriosis; and 46%, 1.67, and 0.75 for intestinal endometriosis. Eventually, the latest systematic review and meta-analysis by Zhang et al., that included a total of 30 studies with 4,565 participants

	reported that the sensitivity and specificity of pelvic examination for the diagnosis of
	endometriosis were 18 -88% and 76 -100%, respectively [23]. The relevance of pelvic
	examination depends on the locations of endometriosis as highlighted by the work of Bazot
	et al. [38].
	The main performances of pelvic examination according to endometriosis location is
	detailed in

examination, sexual abuse in the past, virgo intacta, etc.), vaginal examination should ideally be omitted, and other medical technologies, as described below, should be used as a first step towards diagnosis.

Performance of pelvic examination in women with suspected endometriosis

Unlike questioning, clinical examination has a low sensitivity for the diagnosis of endometriosis, and it is therefore well established that a normal clinical examination does not eliminate the diagnosis: more than 50% of patients with laparoscopically proven endometriosis have a normal clinical examination

[START_REF] Eskenazi | Validation study of nonsurgical diagnosis of endometriosis[END_REF]

. A recent review by Pascoal et al.

[START_REF] Hudelist | Transvaginal sonography vs. clinical examination in the preoperative diagnosis of deep infiltrating endometriosis[END_REF]

and the one of Bazot et al. reporting on 92 consecutive women

[START_REF] Bazot | Diagnostic accuracy of physical examination, transvaginal sonography, rectal endoscopic sonography, and magnetic resonance imaging to diagnose deep infiltrating endometriosis[END_REF]

. In this last cohort, the sensitivity, LR + and LR -values of physical examination were, respectively, 73.5%, 3.3, for uterosacral ligament endometriosis;


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Zhengrui Tu, Jianhao Zhang, Carlos Alonso-Ramos, Xavier Le Roux, Laurent

Vivien, Eric Cassan

To cite this version:


Jean-René Ruault
email: jean-rene.ruault@intradef.gouv.fr

Frédéric Vanderhaegen

Christophe Kolski

How can usage monitoring improve resilience ?

Resilience and systems engineering are key issues for critical systems. The operational usage and states of such systems are quite different from reference ones, generating drift and generate risks. This article suggests functional and physical architectures that fit resilience. Four functions relate to resilience (avoidance, resistance, recovery, adaptation). We develop the avoidance one and define a usage monitoring system that implements it. The case study concerns a railway accident that occurred at Aldershot, Canada. We explain the origin of the gap leading to the accident. The usage monitoring system would allow human operators to understand the situation and avoid the accident.

Introduction

Nowadays, resilience is a key issue for complex system, with many books and articles dealing with resilience [START_REF] Hollnagel | Resilience engineering. Concepts and precepts[END_REF], [START_REF] Ruault | Sociotechnical systems resilience: a dissonance engineering point of view[END_REF], [START_REF] Zieba | Principles of adjustable autonomy: a framework for resilient human machine cooperation[END_REF], [START_REF] Zieba | Using adjustable autonomy and human-machine cooperation for the resilience of a human-machine system, Application to a ground robotic system[END_REF], whatever the domain, in order to cope with unexpected events. Systems engineering is another key issue [START_REF] Luzeaux | Engineering Large-scale Complex Systems in D Luzeaux[END_REF], [START_REF]Systems engineering -System life cycle processes[END_REF]. Many critical and complex systems show a very long lifecycle. We can't foresee all the operational situations that they will meet. The resilience of a system facing unforeseeable events is a critical challenge. The paper suggests a solution to monitor system real states in order to assess drift and to alert human operator of the proximity of hazard. The first part of this paper summarizes the state of the art, for systems engineering and resilience. The second one details a design pattern fit to resilient systems. It contents functional and physical architecture models. It details impacts on the usage monitoring components and on the user interface. The third part applies these concepts to a case study, in the railway domain.

State of the art

The state of the art details the main concepts upon which is based this paper, that are systems engineering, systems architecture, systems modeling language, as well as resilience.

Systems engineering, architecture, SysML

The ISO 15288 standard defines a system as "a combination of interacting elements organized to achieve one or more stated purposes" [START_REF]Systems engineering -System life cycle processes[END_REF], while IEEE 1220 defines it as "a set or arrangement of elements [people, products (hardware and software) and processes (facilities, equipment, material, and procedures)] that are related, and whose behavior satisfies operational needs and provides for the life cycle sustainment of the products" [START_REF]Management of the Systems Engineering Process[END_REF].

For instance, a railway system allows transporting travelers and fret from point to point. Such a system encompasses: end products or services, for instance, travelers transportation, fret transportation; equipments and devices producing these end products and services that are trains, stations, traffic management systems, sale systems; enabling systems, that are CASE tools or test tools; end users specified processes and activities, such as driving train, managing traffic, vending tickets, conforming regulation rules; end users specified profiles, roles and responsibilities, such as engineers, traffic managers, structure organization, that specifies both end users profiles, roles and responsibilities, as well as processes and activities; resources, such as electricity.

The "system in use" is quite different to the "system as designed". End users behave to reach performance goals, control their activities, adapting them function of contextual contingencies and improvement of performance requirements, and resolve system dysfunctions and failures. Most of the security and safety analysis are based upon foreseen and predictable failures and do not take into account unforeseen and unpredictable events. So, the system is not designed to perform in such a way and the users have to resolve the gap between the unpredictable events and the system functions. The system architecture models describe the organization of the functions and the components of the system. Main architectural points of view are:  The operational one: why is the system designed and built? What are its missions and goals? What are the operational missions in which it will be used?  The functional one: what are the services that the system provides to its environment? What is the organization of these services?  The physical one: how the system's components interact together in order to provide these services? Nowadays, the system modeling language (SysML) provides a set of diagrams in order to elaborate these models [START_REF] Friedenthal | A Practical Guide to SysML[END_REF]. These diagrams allow modeling structure and behavior of a system. Moreover, including requirements diagram, SysML allows traceability between models and requirements. SysML is a key driver of model based systems engineering. This set of diagrams contents:

Resilience functions

Resilience is an extrinsic relational property of a system. It characterizes its property "to cope" with adversity where the disturbance is unforeseeable. Authors of the "Resilience engineering" book [START_REF] Hollnagel | Resilience engineering. Concepts and precepts[END_REF] states: "Resilience is capacity of a system or an organization to react and recover after a disturbance, with a minimal effect on dynamic stability". Moreover, resilience is complementary and adds value to other system safety method.

Luzeaux [START_REF] Luzeaux | Engineering Large-scale Complex Systems in D Luzeaux[END_REF] characterizes resilience as a "management at the border of the domain of application… The challenges linked to resilience include the management of that which is uncertain or unplanned, accidents, the transition between more or less catastrophic circumstances while avoiding a true catastrophe, and the return to a more normal operational status". Luzeaux [START_REF] Luzeaux | Engineering Large-scale Complex Systems in D Luzeaux[END_REF] differentiates four main resilience functions which complements each other: 1) avoidance (capacity for anticipation); 2) resistance (capacity for absorption); 3) adaptation (capacity for reconfiguration), and 4) recovery (capacity for restoration). We focus now on the first key function for resilience: avoidance [START_REF] Luzeaux | Engineering Large-scale Complex Systems in D Luzeaux[END_REF]. The avoidance function consists of acquiring information at the operators' level in order to anticipate and to avoid the accident, that is: (1) To obtain a representation of the environment; (2) To obtain a representation of the system dynamics: (3) To identify the environment states that were not envisioned; (4) To evaluate the instantaneous or trend drifts; (5) To evaluate the proximity of the state of the system compared to the hazard.

These functional elements impact the architecture of the system of interest, enabling systems architecture, since we give to operators an appropriate situation awareness representation. Resilience is the dynamic process that allows the crew to understand the current situation, to learn and develop adequate behaviors to take into account environment adversities and to adapt as well as possible. It is the capacity of a sociotechnical system to continue to evolve and fulfill its operational mission in spite of the difficult conditions, serious constraints or events, sometimes severe damages or losses. This adjustment capability is based upon the dynamic process of "visual piloting". The system must have a great capacity to estimate its position with regard to the danger zone [START_REF] Luzeaux | Engineering Large-scale Complex Systems in D Luzeaux[END_REF]. The system must be designed to cope with uncertainty. It is necessary to specify the envelope of required, desir-able, even acceptable, execution and to require that the system recognizes the situations where it is likely to leave this envelope. "Resilience is obtained via the system capability to monitor conditions at the edges of the performance envelope, determining their value and the usual distance from the edge and the ability to adapt the operational behavior of the system to potential developments in the enve-lope…" [START_REF] Luzeaux | Engineering Large-scale Complex Systems in D Luzeaux[END_REF]. The objective is to qualify and quantify the drift of the system towards the state of failure before a major breakdown occurs.

In many cases, the system has been designed to be safe under specified conditions, but there are no means to monitor the system when it operates under unspecified conditions, and to reassess actual risk. Safety under this situation is neither monitored nor controlled. The resilient management consists of clear, relevant and shared situation awareness, among all the communities, which implies to assess the gap between the specified path and the actual one as usual fluctuations or, on the opposite, the trend of a forecast latent deviation.

Hardy [START_REF] Hardy | The system safety skeptic[END_REF] expresses that "plans that do not reflect reality may create the impression that effective organization is in place and that risks have been reduced, when in fact large risks could exist". This difference may grow from the beginning of the operation of the system, from step to step, generating a gap between the plans and the reality. The figure 1 expresses this difference and the gap. The specified path deals with the specified task [START_REF] Leplat | Erreur humaine, fiabilité humaine dans le travail[END_REF], or the work-as-imagined, taking place along the time. It contains specified local variability included within tolerance margins that is everyday or 'normal' variability [START_REF] Hollnagel | FRAM: The Functional Resonance Analysis Method[END_REF] as defined a priori. The actual path, among other possible ones, denotes the actual activity [START_REF] Leplat | Erreur humaine, fiabilité humaine dans le travail[END_REF], or the work-as-done [START_REF] Hollnagel | FRAM: The Functional Resonance Analysis Method[END_REF], of the sociotechnical systems, function of met contingencies. This actual path contains actual local variability, since these contingencies are not stable and linear. The gap between these two paths is due to unusual conditions, 'out-of-range' variability [START_REF] Hollnagel | FRAM: The Functional Resonance Analysis Method[END_REF], that is not an isolated case, but a huge trend. These unusual conditions may be new and unforeseeable working environments conditions. By coming of A, the real dynamics by-passes the barrier in 1 (cf. figure 1), moves towards B, then C, to join D and E by by-passing of new the barrier in 2 and 3. This real dynamics of A in E expresses a gap which can be far from the prescribed dynamics, as it is the case B. Nobody can estimate this gap. Nobody is conscious of situation and can estimate the risk infers by the drift. Stage after stage, the dangerous actions increase the risks (), until the accident (E). The critical issue is the capacity of the user interface to give to the operators a shared situation awareness and to allow a navigation at sight. It is necessary to compare the real states and usage of the system and the reference ones.

Design pattern fit to resilient systems

We elaborate a design pattern that fits resilient systems. This design pattern declines the avoidance function in a functional architecture, then in a physical one. We will decline the other functions in further articles. The main functions of the resilience are avoidance, resistance, recovery and adaption. In this article, we detail the avoidance function.

Functional architecture: monitor system's usage and current state

The goal of this function is to be aware of the current situation compared with the specified one that is the drift compared with the nominal path, the proximity of hazard, and the safety margins.

It consists of gathering information about the system, its dynamics, its environment, and alerting operator when the system deviates from its nominal path. This function (figure 2) is decomposed into these following four functions on which we focus: (1) To obtain a representation of the system dynamics; (2) To evaluate drifts; (3) To evaluate proximity of hazard and (4) To alert operators. These functions are allocated to components in the physical architecture of the usage monitoring system.

Physical architecture: usage monitoring components

These four functions are allocated to the usage monitoring system. It provides two sets of services respectively for these two functions: (1) To obtain a representation of the system dynamics; to gather usage from operating parts of a system;

(2) To alert operators; to express warning. The two other functions are implemented inside the usage monitoring system that encompasses a set of components that are:

 Usage sensor proxies are closely nested to the security devices or other components of the systems, gather their states and usages and send them to the respective usage sensors. Each component and security device that contributes to resilience has a usage sensor proxy that fits to it.  Usage sensors get the states and usages of devices and components and translate them in order to be analyzed. Each component and security device that contributes to resilience has a usage sensor that fits to it.  Current state repository stores the data coming from the usage sensors whatever they are, in order to assess trend drifts. It deals with reality [START_REF] Hardy | The system safety skeptic[END_REF].  Reference state repository contains models that specify security, including specified variability, barriers characteristics, as well as more specific data. It deals with plan [START_REF] Hardy | The system safety skeptic[END_REF].  States comparison engine compares the current states and the reference ones, in order to assess drifts and evaluate the proximity of hazard. It sends warning levels, safety margins and drifts to the user interface proxy.  User interface proxy is closely nested to the other user interface of the system and expresses warning in order to alert human operators.

The table 1 shows the allocation of resilience functions on the usage monitoring system components. The block definition diagram (figure 3) shows the physical architecture of the usage monitoring system, and each component with its operations and attributes, that have to be tailored in order to fit domain specificities and safety stakes.

Impacts of the usage monitoring components upon functional and physical architectures of whole system

The system architecture must evolve in order to link together the operating system and the usage monitoring system. We differentiate two parts. On the one hand, the operating system implements the core functionalities, that is the part that reach the goals and realizes the operational missions. On the other hand, the usage monitoring system implements the avoidance functions of the resilience. Any kind of systems can implement this pattern, rail traffic management systems as well as trains, tracks or stations (figure 4). For each of these different systems, their operating parts exhibit usage and state, as well as their specific functionalities. On the other side, their usage monitoring parts gather usage and express warning. That implies interfaces and flows between these two types of parts (figure 5). The operating system exhibits usage, for instance current variability, barrier state, among other safety information. The usage monitoring system gathers these information and, function of the real state of the operating system, expresses warning in order to alert the operators, such as safety margins, drift or proximity of hazard.

Impacts of the usage monitoring components upon user interface

The system architecture must evolve in order to express the warning to the operators, via the relevant user interfaces. This relies on the capacity to measure its current internal states and explain the gap between them and the reference ones. These interfaces must be designed in order to express safety margins, hazard proximity and increase of risk level. So, the operators can regulate their activities, evaluate the differences between the current system situation and the system field of definition, and detect, as soon as possible, the migration or compensation mechanisms. We suggest a solution that needs to be assessed with operators. It expresses the progressive drift from secure situation to risky one [START_REF] Ruault | Sociotechnical systems resilience: a dissonance engineering point of view[END_REF]. The operators must be able to see that the system is in a high risk zone with catastrophic consequences. Since that the operators are awarded of the proximity of hazard, they can take care, improve procedures and monitor the real state of the system.

Case study: railway accident

The application is the railway accident that occurred at Aldershot station [START_REF]Railway Investigation Report R12T0038, Main-track Derailment[END_REF]. According to the accident report [START_REF]Railway Investigation Report R12T0038, Main-track Derailment[END_REF], "On 26 February 2012, VIA Rail Canada Inc. passenger train No. 92 (VIA 92) was preceding eastward from Niagara Falls to Toronto, Ontario, on track 2 of the Canadian National Oakville Subdivision near Burlington, Ontario. VIA 92". The investigations show that while approaching the Aldershot station, the crew encountered a first signal (Clear to Limited) and then another one (Clear to Slow). The signals were specifying to proceed and approach signal 334T2 located east of the Aldershot station at 24 km/h (15 mph). This consecutive information was part of the signal indications governing VIA's 92 movement in order to pass from the track 2 to the track 3. However, the stop at the Aldershot station was an event that interrupted the signal progression. Hence the crew was more preoccupied by stopping the train at the station than proceeding to the signal 334T2 with appropriate speed. During the stop, there was no fur-ther indication to remind the crew of the previous signal. This event laid to the interruption of the signal indications, promoting oblivion of the past information. Moreover, in 99 % of the cases, the train of the company circulated on the track 2. This day, works were realized on the track 1 and the track 2. An authorization to occupy the track was granted to the team in charge of these works by the controller of the rail traffic. The team of exploitation of the train was not informed about these works. The train had to pass of the track 2 in the track 3, via a crossover between track 2 and 3. This instruction was communicated by the railway signals which the team of exploitation is supposed to apply scrupulously. The speed on this connection was limited to 24 km/h (15 mph). The team of exploitation understood too late the situation. The train entered on the connection a 108 km/h speed (67 mph) and went leaned. When a passage of the track 2 to the track 3 is necessary, this passage is realized on a crossover for which the authorized maximal speed is 72.42 km/h (45 mph). The day of the accident, the situation was quite different. The drivers VIA Rail had to pass of the track 2 in the track 3 on a crossover as which the authorized maximal speed was of 24 km/h (15 mph). This situation, the day of the accident, generated an important gap between the specified speed, adapted to pass on the crossover, and the real speed of the train. The instruction of speed was shown on the railway signals, before Aldershot station in which the train stopped. There was no reminder of the specified speed when the train restarted of Aldershot station. The speed of the train was excessive and the capacity to brake insufficient to enter on the points limited in 24 km/h (15 mph). The drivers were not conscious of this gap. When they understood the situation, it was too late. The drivers were not able to avoid the accident. An usage monitoring system is useful for detecting the major violations of safety. In the case study of the Aldershot station railway accident, a usage monitoring system would have been helpful for the following issues:

 Detecting the speed excess by comparing it to the accepted threshold and presenting the evidence of a speed exceeding to the operators.  Managing the rail crossing between rail 2 to rail 3 by alerting the operators or presenting a visual device with the maneuver to be accomplished.  Reporting the railway signals to the operators in real-time in order to keep them informed and secures the situation awareness of the operating crew.

Indeed, from the moment when the VIA 92 entered the crossover No. 5 (1) with excessive speed, consistent with the crew misperception of the railway signals (2), it could be imagined that the usage monitoring system would have reported the anomaly through the usage sensor components. Hence, during the stop at the Aldershot station, interrupting the continuous progression of signals (3) (4) the usage monitoring system might have been helpful to the operators for understanding the situation compared to the reference state (specified path cf. Fig 1 ) with the state comparison engine component.

Among other possibilities, we suggest an architecture allowing showing to the drivers this gap so that they become aware of the situation and adapt the speed in a appropriate way. The specified speed and speed limited to 24 km/h (15 mph) must be transmitted by the traffic management system in the train, in order to the usage monitoring system can compare these speeds with the real one. The drivers owe informed about the speed limited to 24 km/h (15 mph) of the points which they have to take. That needs to communicate to the drivers of the specified speed, the maximal speed authorized on the points, the gap between the specified speed and the real speed, as well as the necessary distance to brake before to engage on the points.

Both rail traffic management system and train system (figure 6) contents an operating subsystem and a usage monitoring one. The train system gathers specified speed and crossover maximum speed in order to evaluate this information compared to the actual speed and alerts the drivers about the over speed. Other solutions exist. For instance, a signal after the station informs all drivers of conditions beyond the station, or an adaptive speed limiting based on signals communicates from train to train, in order to prevent collision.

Conclusion

Our proposal consists in interconnecting the operating system, which realizes the operational missions, and the usage monitoring system. This interconnection allows monitoring the state, the usage of the system, to estimate the gap between the current state of the system and the safe one, to estimate the proximity of hazard, and to inform the operators. The goal is that the operators share a clear, reliable, relevant and updated representation of the operational context as well as the usage of the system, so that they can take the appropriate measures. The first stage, object of this paper, is to design a system architecture implementing this in-terconnection to monitor the usage of the system. A second stage will consist in widening this architecture to observe the operational context and express it to the operators. A first difficulty lies in the determination of issues to be observed, in particular the behavior which cannot be a priori envisioned. A second difficulty lies in the reliability and the fidelity of the measures. Indeed, the lack of information, or false information, would be error prone and accident prone. Finally, benchmark models allowing estimating this drift have to be available in the system in exploitation, and to correspond to the real configuration of the system.

( 1 )

 1 Structure diagrams set (block definition diagram and internal block diagram); (2) Behavior diagrams set (activity diagram, sequence diagram, state machine diagram and use case diagram); (3) Parametric diagram; (4) Requirements diagram and, (5) Package diagram.

Fig. 1

 1 Fig. 1 Specified and actual paths of a sociotechnical system [10].

Fig. 2

 2 Fig. 2 Functional decomposition of the avoidance function (block definition diagram).

Fig. 3

 3 Fig. 3 Physical architecture of the usage monitoring system.

Fig. 4 A

 4 Fig.4A whole system containing an operating system part and an usage monitoring system one.

Fig. 5

 5 Fig. 5 Interfaces and flows between operating system and usage monitoring system (internal block diagram).

Fig. 6

 6 Fig. 6 Communication of specified states from the rail traffic management and the train.

Table 1 :

 1 Allocation of resilience functions on the usage monitoring system components.

	Functions	Obtain a repre-	Evaluate	Evaluate the proximity	Alert
		sentation of the	the drifts	of the system compared	operators
		system dynamics		with the hazard
		Public service Internal	Internal function	Public
	Components		function		service
	Usage sensor proxy	X
	Usage sensor	X
	Current state repository		X	X
	Reference state repository		X	X
	States comparison engine		X	X
	User interface proxy				X

bdd [Package] Usage_Monitoring_System [Usage_Monitoring_System]

	Name: Package:	Usage_Monitoring_System Usage_Monitoring_System	«Usage_Monitoring_System» Usage_Monitoring_System		«Usage_Monitoring_Component» Reference_States_Repositoty
	Version: Author:	1.0 Ruault	+ Gather_Usage() + Express_Warning() :Warning	1	«Reference_State» + Numbrer_Authorization :Reference_State
					+ Specified_Variability :Reference_State
					+ Barrier_Characteristics :Reference_State
		1..*
					+ Set(Reference_State)
		«Usage_Monitoring_Component»
		User_Interface_Proxy			1
	+ Show_Warning_Level(Warning_Level)			«Usage_Monitoring_Component»
	+ Show_Safety_Margins(Safety_Margins)			Current_States_Repository
	+ Show_Drift(Drift)
			1..*		«Current_State» + Numbrer_Authorization :Current_State*
		«Usage_Monitoring_Component»		+ Current_Variability :Current_State
		Usage_Sensor_Proxy			+ Barrier_Status :Current_State
		«Usage»			1..*
		+ Gather_Usage() :Usage			«Usage_Monitoring_Component»
			1		Usage_Sensor
		«Usage_Monitoring_Component»		«Current_State»
		States_Comparison_Engine		+ Barrier_Status :Current_State
	+ Assess_Drift(Current_States_Repository, Reference_States_Repositoty) :Drift + Assess_Warning_Level(Reference_States_Repositoty, Current_States_Repository) :Warning_Level		+ Number_Authorization :Current_State + Current_Variability :Current_State
	+ Assess_Safety_Margins(Current_States_Repository, Reference_States_Repositoty) :Safety_Margins		«Usage»
					+ Gather_Usage() :Usage


Matthieu Duroyon
email: matthieu.duroyon@renault.com.

Nicolas Misdariis

Patrick Susini

Nicolas Dauchez

Louis-Ferdinand Pardo

Eléonore Vialatte

How do Automotive Acousticians talk about Sounds and Comfort in Electric Vehicle?

Keywords: Acoustic comfort, Sound Design, Electric vehicle, Interviews

The original idea of this work is to propose an improvement in the acoustic comfort inside electric vehicles, by designing sounds added to sounds perceived as unpleasant thanks to the audio system of the car. The first step in the sound design approach consists in identifying and describing sounds. Therefore, we start by extracting a lexicon spontaneously used by automotive acousticians. The choice was made to conduct 12 interviews guided by a semi-structured questionnaire. The resulting interviews are then analyzed to classify the extracted terms into 4 categories of descriptors formalized in previous studies, illustrated here with examples: Hedonic (e.g. Pleasant), Causal (e.g. Electric motor), Reduced (e.g. High pitched) and Names (e.g. Whining noise). The second step in our framework is to describe the hedonic perception of comfort/discomfort of these sounds using the contextual elements given by the participants. This issue is addressed by obtaining a verbal portrait of the acoustical characteristics perceived as pleasant and unpleasant. We present here the ranking of the most representative sound sources identified in the car cabin as well as their perceptive definitions, focusing on the sound properties and comfort/discomfort impact spontaneously given by participants. The sound design process will be further explored.

INTRODUCTION

The automotive industry always had a strong link with acoustic and sound design. Sonic qualities of vehicle are often advertised by the manufacturer [START_REF] Bijsterveld | Listening to the sounding objects of the past: The case of the car[END_REF]. The acoustic signature of 6 or 8 cylinders combustion engines are known to add a luxurious or sportive characteristic to the vehicle. Therefore, these properties were imitated, or "augmented", in some thermal vehicle through the audio system with a technology called ESE (Engine Sound Enhancement) [START_REF] Brandl | Nvh challenges and solutions for vehicles with low co2 emission[END_REF][START_REF] Kwon | Model of psychoacoustic sportiness for vehicle interior sound: Excluding loudness[END_REF]. The arrival of the electric vehicle and its relative silence brought a whole new set of questions and perspectives to sound designers and acousticians. The most emblematic example is the design of the AVAS (Acoustic Vehicle Alerting System) to improve pedestrian safety, with the constraint of keeping an ecologic validity of the vehicle's sound [START_REF] Misdariis | Knowledge in Sound Design -The Silent Electric Vehicle: a Relevant Case Study[END_REF]. This artificial sound is now mandatory for every new electric vehicle below 30 kmph [UE 540/2014, art. 8]. Another consequence of the vehicle electrification is the emergence of new sounds or sounds that were previously masked by the thermal engine. These sounds could be a source of discomfort for the user. If these sounds can not be reduced, is it possible to develop an augmented acoustic method to improve comfort?

The aim of this work is, first, to identify sounds inside electrical vehicles that have an impact on comfort, and then, to develop an "augmented acoustic" method based on the description of these sounds to improve comfort through sound design. This paper deals only with the first question. The identification and description of these sounds must be linked with a shared meaning between the different actors of the project to allow a good communication between engineers, researchers and sound composers [START_REF] Misdariis | Mapping sound properties and oenological characters by a collaborative sound design approach-towards an augmented experience[END_REF]. Several works were carried to identify methodologies to communicate on sounds in a sound design context with words [START_REF] Carron | Speaking about sounds: a tool for communication on sound features[END_REF], imitations [START_REF] Delle Monache | Embodied sound design[END_REF], gestures [START_REF] Houix | Sonically Augmented Artifacts: Design Methodology Through Participatory Workshops[END_REF] ... In our work we will focus on the verbal description of sounds. Chion [START_REF] Chion | Audio-Vision: Sound on Screen[END_REF] established 3 modalities of description in common language if we exclude quantitative description, imitation and onomatopoeia: causal description, reduced description and contextual description. Causal description refers to the physical origin of the sound and is similar to the "everyday listening" mentioned by Gaver [START_REF] Gaver | What in the world do we hear?: An ecological approach to auditory event perception[END_REF], reduced description, first introduced by Schaeffer [START_REF] Schaeffer | Traité des objets musicaux [treatise on musical objects[END_REF], refers to the properties of the sound independently of the object creating it. Contextual description refers to the functionality of the sound, the context around it or his intention. Contextual description often contains complex formulations such as complete sentences. To build our lexicon, we will only focus on single words related to emotion or judgment, and call this subcategory "hedonic descriptors". This category will enable us to identify the sound characteristic that has an impact on comfort. This 3-level description will also structure the definition formulation for our lexicon.

The definition of comfort is still an open question, it could simply be described as the opposite of discomfort but such a definition proved not to be sufficient [START_REF] Zhang | Identifying factors of comfort and discomfort in sitting[END_REF]. The definition of comfort needs to take into account multiple aspects, from physical measurements to users' expectations [START_REF] De Looze | Sitting comfort and discomfort and the relationships with objective measures[END_REF][START_REF] Vink | Comfort and discomfort studies demonstrate the need for a new model[END_REF]. We propose this definition of comfort: "Comfort is a subjective sensation making a manufactured object pleasant in its use and coherent with the users' expectations." highlighting the importance of the expectation and contextual use of a designed object in its comfort evaluation.

Because the literature around sound in the electric car cabin and more precisely its perception is not abundant, we decided to conduct a free verbalization task. This work will involve automotive acousticians that are knowledgeable in the acoustic of the vehicle and its perceptive impact. Thus to explore the vocabulary of the electric vehicle cabin, we follow a method already used in the exploration of soundscapes [START_REF] Dubois | A cognitive approach to urban soundscapes: Using verbal data to access everyday life auditory categories[END_REF][START_REF] Tardieu | Perceptual study of soundscapes in train stations[END_REF][START_REF] Guastavino | The ideal urban soundscape: Investigating the sound quality of french cities[END_REF] or sound description [START_REF] Paté | Influence of the electric guitar's fingerboard wood on guitarists' perception[END_REF][START_REF] Rosi | Investigating the shared meaning of metaphorical sound attributes: bright, warm, round, and rough[END_REF], called the semi-structured questionnaire.

The paper is organized as follows. The first section presents the work that went into the redaction of a semi-structured questionnaire and the interviews conducted. The second section presents the first analysis enabling us to extract a spontaneous lexicon used by acousticians to describe sounds in the electric car cabin. The third part presents the work in progress to formulate definitions of these descriptors and their positive/negative impact on comfort.

METHOD 2.1 Semi-structured questionnaire

We decided to conduct our questionnaire through interviews for several reasons. The first one is that we believed this way would enable a more diverse and spontaneous verbalization by the participants [START_REF] Tardieu | Perceptual study of soundscapes in train stations[END_REF][START_REF] Paté | Influence of the electric guitar's fingerboard wood on guitarists' perception[END_REF]. The second reason is that sound description is known to be a difficult task for people that are not used to it [START_REF] Dubois | A cognitive approach to urban soundscapes: Using verbal data to access everyday life auditory categories[END_REF]. Moreover, we wanted participants to avoid focusing their description on the cause of the sound instead of the perception. Therefore the role of the interviewer was to constantly guide the participant along, to enhance reduced and hedonic description with the causal description they naturally give. The interview methodology was to first let the speaker give a sound description by the cause (Q. 4) and then use the different causes given to help them verbalize and develop the reduced and hedonic aspect while taking care not to induce the participant in saying any concept or vocable he would not have mentioned. This also enables us to obtain technical information needed to reproduce or record specific sounds in the following. The third reason we decided to choose the interview format is to ensure each participant answered these questions in a similar way, within the same time spent.

Our questionnaire is aimed to elicit sound description on the 3 aspects identified causal description, reduced description contextual description. The first part of our questionnaire tackles the issue of sound description and causes.

• Q1. According to you, what big a role does hearing play in your profession?

• Q2. Could you list the sounds you worked on, during the past year?

• Q3. Among the sounds you listed, could you pick up 3 specific sounds?

• Q4. Could you describe the technical origin of these sounds?

• Q5. Could you now describe the sound itself, focusing on the sounds properties and not referring to the cause?

• Q6. After our discussion, do you see any additional words you did not mention?

The second part asks questions about the components that have an impact on comfort. The questions here closely converge toward the notion of augmented acoustic and sound design. • Q8. How would you define it?

• Q9. Is there any specific sound in the car cabin you would qualify as uncomfortable? Comfortable?

• Q10. Would we be able to design a sound played by the audio system of the car that would correct the uncomfortable property identified?

Participants

We selected a list of 15 potential participants for our semistructured interviews among Renault's acousticians based on their experience on electric vehicles and automotive acoustics. We contacted each of these participants in the same way, by sending a first e-mail presenting the global topic and asking if they would volunteer in this study. A 20 minute phone call gave afterward further details on the subject and answered the potential questions. These 20 minute phone calls were also useful to build the relationship suggested by Tardieu [START_REF] Tardieu | Perceptual study of soundscapes in train stations[END_REF] to carry an interview. Among the 15 people approached, 12 volunteered to take part in the study (3 females, 9 males) , with 5 to 26 years experience in automotive acoustics (with an average of 17 years). All participants reported a regular use of electric vehicles.

First results

The whole interview was set to last 1 hour, the shortest was 45 minutes long and the longest 1 hour, 32 minutes (with an average of 1 hour, 12 minutes). The first 2 participants were interviewed a few weeks before the others and were selected for their more extensive knowledge on the subject. We took the time to discuss the clarity of every question and the general feeling of the interview before interviewing the other ten participants. Minor modifications were made following these 2 interviews. The first was to avoid complex terms such as "causal", "hedonic" or "reduced" in the questions and rather use periphrases to explain these notions. The second modification is that we added systematical questions asking for example of sounds that can depict these discussed characteristic. In the following, all 12 interviews are considered identical. Each of the interviews were recorded and transcribed for the further analysis. The participant approval for the recording was explicitly asked before the interview and recorded at the beginning of the discussion. The interviews were led both remotely (33%) and face-to-face (66%); face-to-face were easier to lead and last 15 minutes less than remotely in average (1h08 vs 1h23). This difference might be explained by the difficulty to speak simultaneously during the exchange and the lack of non verbal communication in the case of video call. Apart this, no noticeable differences were observed between the 2 modalities.

ANALYSIS

Word classification

A 4th category is added To the 3 categories previously identified, which is a subcategory of the causal description: "Sound Names", that is useful to accurately identify a sound by the name commonly used by the participants. In the following, we will mainly focus on 3 categories: "Names", "Hedonic descriptor" and "Reduced descriptor", because the sound names category is included in the causal category but is more likely to include single word descriptors, which will be treated more easily in the following. This categorization has been manually performed by the author based on the written transcription of each of the interviews. We now have a set of words stored as a table (Table 1).

Table 1: Overview of the different descriptors classified in the 4 categories identified (Name, Causal, Hedonic, Reduced), with a namecode for each sentence.

Namecode Names Causal Hedonic Reduced MDs01 Name1 Hedo1 Reduced1 PBs12 Name2 Cause1 PBs53 Name3 . . .

Descriptor ranking

The first step of the categorization enables us to extract the candidate words for our lexicon and classify them. The second step aims at identifying the key words by ranking them. To do so we explore two methodologies (Fig ). The first one is the more natural one: word frequency analysis. We first achieved a stemming of the words previously classified, therefore adjectives (e.g. strong), adverbs (e.g. strongly), comparatives (e.g. stronger) and superlatives (e.g. strongest) will be reduced to the root (e.g. strong-) and treated as a unique descriptor. We had concerns about the biases this methodology might have: first, the format of the interviews might incite participant or the interviewer to repeat a word for clarification purposes, increasing its frequency, whereas a unambiguous descriptor might be pronounced a single time. The second bias that is inherent to this methodology is the lack of differentiation between synonyms ("Bass" and "Low Frequency") that would be considered as 2 different descriptors. We thus decided to explore a more automatic analysis trough a known text analysis software: Leximancer. This software is known to be based not only on word frequency but also on co-occurrence of words. Leximancer identify Concepts among a list of Seeds. Seeds are automatically identified among the words appearing the most frequently in the text or the words in a list provided by the user. Concepts are identified by clustering seeds together depending on a weighting function based on 2 parameters: the crosscorrelation of these seeds and the distance they have in the text. Once the Concepts are identified, they can be ranked and rated by applying a data reduction method on the correlation matrix of the different concepts identified in the text [START_REF] Smith | Evaluation of unsupervised semantic mapping of natural language with leximancer concept mapping[END_REF][START_REF] Sotiriadou | Choosing a qualitative data analysis tool: A comparison of nvivo and leximancer[END_REF]. Leximancer then produces a concept map, illustrating the link identified between concepts (Fig. 2).

Leximancer suggests default settings values to perform the analysis depending on the text size and type. The only parameter we changed was a concept seed identification parameter by choosing 'Total Number of con-cepts=100' and 'percentage of name like concept =70 %' which is significantly higher than the default value recommended. This difference is explained because we will create a large quantity of Name-Like concepts. Name-Like concepts are detected among seeds starting with a capital letter; we thus provide a seed list by turning every descriptors previously identified Fig. 1 (High, Low, Pleasant...). Leximancer will also identify concepts by itself (30 %), but none of the self identified concepts were used in the following. We also kept the 'Dialog Tag ON 'to identify the speakers but did not use this functionality and made no difference between speakers, including the interviewer. This way the Leximancer analysis will use the complete text with the default parameters to rank and identify the concepts we highlighted with a capital letter.

into a Name-Like concept

Comparison of the different rankings

We plot in Fig 1 . the first 33 descriptors from the word frequency analysis and the concept analysis of Leximancer, Fig. 3 and Fig. 4 give the result for the sound names and reduced category. Because the values of concept occurrences and word occurrences cannot be meaningfully compared, we instead compare the occurrence percentage descriptors have. We first rank the same dataset of descriptors by word frequencies (top figure) then by concept occurrence (bottom figure). This way, we can easily highlight the difference in behavior.

The interviews were carried in French, each word has been translated into English with Deepl and the associated bilingual concordance tool, Linguee. The only de-scriptor that did not followed this protocol is "whining" (sirènement) this name have already been identified in the industry and academic field and called "whining noise" or "whine noise". The translation offered by the mentioned tool was not satisfactory and did not fit this. The causal description of the sounds given by the participant could ensure this English word do correspond to the same sound.

We can identify descriptors getting different values depending on the method. "Good" and "Strong" are the most blatant examples. "Good" is considered as irrelevant to Leximancer because it is a stop word, especially in French where it is very often used in oral expressions to signify a conclusion or transition. On the other hand, the word "Strong" is not identified as relevant because of his high correlation and low distance with the word "Level" in its use, therefore these 2 words have been automatically merged in the more global "Level" concept. This might also explain the difference of percentage between the concept "Level" and the occurrence frequency of the word "Level". Another example very tricky for both methods in our analysis is the descriptor "Harmonic". This descriptor is either used as an adjective or noun, and the adjective might have different meanings depending on the context. Based on the author observation during the interviews, the noun "Harmonic" is often used in the same meaning as "Tone". The adjective, on the other hand, is either used to refer to its mathematical meaning, i.e. a sound composed of a fundamental frequency f 0 and frequencies f i multiple of the fundamental, or used to describe the link between the pitch of a sound with the rotation speed of an element: the complete formulation would be "motor rotation harmonic" (electric motor, compressor, gears...) but abbreviated "harmonic". Some sounds could be described as "harmonic" because the pitch is proportional to the rotation speed of the engine, despite that at any given rotations per minutes the spectrum does not show harmonic behavior.

To build our lexicon we will take the basis of the 13 first sound names identified by Leximancer (Fig. 3). These 13 descriptors represent more than 90 % of the words and concepts identified as sound names.

SOUND DEFINITION

The aim of this section is to present the methodology explored to formulate definitions for the names descriptors identified in the previous section and its first results.

Methodology

We explore a 3-step methodology to propose a perceptive definition and give a verbal portrait of the different sounds identified. We formed a grouping work of 3 members, including 3 authors. This jury does not have any specific experience on automotive but do have a knowledge on sound design and perception. For each sound this jury will perform the following tasks:

• The main author establish the list of hedonic and reduced descriptors previously identified Fig. 1 used by each of the participants and extract the specific audio of the interviews describing the sound.

• With these 2 documents (the list and the audio), members of the jury provide their own definition of the described sound and a ranked list of the most relevant descriptors. The definition should have one sentence referring to the causal description of the sound, one for the reduced aspect and a last one for hedonic aspect.

• Definitions are then merged together. The experts, who took part in the interviews and mentioned the Let us give an example, translated from French: Hoot (Hululement): Cavity mode, of a tyre around 80 km/h for instance, produces a sound also called "Hoot". It corresponds to two near low frequency lines, in low frequency (≈ 200 Hz), with a fast amplitude modulation rate (≈10 Hz) very similar to a beating. Its emergence (≈6 dB) in comparison with a broadband noise (rolling) makes it identifiable. This sound is constant in frequency, amplitude and modulation velocity, which makes it exhausting.

The work in progress consists in illustrating definitions with examples containing sounds. The complete lexicon could then be presented online on the SpeaK platform https://speak.ircam.fr/ [START_REF] Susini | The speak project: A collaborative platform for presenting and sharing sound lexicons[END_REF].

CONCLUSION AND PERSPECTIVES

We explored a methodology to extract a meaningful list of words to describe a specific sound environment, the electric car cabin, which do not benefit a wide literature or user's community because of its novelty, originality or specificity. This list of words is then used to build a full lexicon, including definitions and sound examples, where the descriptors used have been identified through a text analyzer on a free verbalization task: a semi directive questionnaire. We compared 2 different text analysis methodologies: a classical word frequency and an automated one, Leximancer. The limitations of both methods are illustrated by several examples. The first one are descriptors such as "Harmonic", where the meaning of this word strongly depend on the context, for instance if it is used as a name or adjective. A second are descriptors such as "Strong" and "Level" are strongly correlated in their usage. A last example are descriptors not mentioned earlier such as "Rough" or "Smooth" that could either describe a sound or road surface. Even if such descriptors are identified by our analysis, there is a legitimate doubt on the relevance for a lexicon describing sounds, a doubt which can not be satisfactorily erased by either method. Identifying the right descriptors to represent a sound environment still requires a human action. We decided to reduce this human intervention to the formulation of a definition through a jury composed of 3 people working on sound perception, followed by a validation by the automotive experts. This gives us a first a posteriori comparison of the reduced descriptors used by the jury and identified by the text analysis.

Following this, several perspectives appears. First, finalize the lexicon by completing the work in progress on definition and sound illustration. Second, design augmented sounds that would modify the perception of an environment and making the atmosphere more comfortable. To achieve this, the lexicon will help identify the most critical aspects of the sound and how to treat them. The first step will be to replicate sounds and their reduced characteristics identified in the definition formulation, before being able to augment some of their properties. A third perspective could be to use this lexicon to obtain verbal portraits of specific target atmospheres, already identified in the car industry, that would give a sound description for a sound design.

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  Q7. According to you, what place does sound comfort has in your profession?

Figure 1 :

 1 Figure 1: Histogram comparing the descriptor occurrences with word frequency (Method1) analysis and Leximancer (Method2). The top figure is ranked by word frequency and contains 83% of word occurrences and the bottom figure is ranked by concept frequency in Leximancer and contains 87% of concept occurrences.

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 1

Figure 2 :

 2 Figure 2: Concept map output by Leximancer. Concepts are represented by nodes and clustered as "Themes" depending on the distance computed between concepts, materialized by the bubbles. Nodes are bigger when the concept is more important in the data set.

Figure 3 :

 3 Figure3: List of the sound names descriptors used in the following. We ranked the descriptors following the Leximancer concepts occurrence and kept the word frequency values to enable comparison. 93% of concept occurrences are represented and 91% of word occurrences related to sound names.

Figure 4 :

 4 Figure 4: List of the reduced descriptors used. We ranked the descriptors following the Leximancer concepts occurrence. 85% of concept occurrence are represented and 67% of word occurrences related to reduced description.

ACKNOWLEDGMENTS

The authors are very grateful for the 12 acousticians from Renault group who shared their time and knowledge to achieve this work. This publication was supported by ANRT under a CIFRE contract [2021/1063] with Renault group.