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Speech communication relies on articulatory and acoustic codes shared between speakers and listeners despite inter-individual differences in morphology and idiosyncratic articulatory strategies. This study addresses the long-standing problem of characterizing and modelling speaker-independent articulatory strategies and inter-speaker articulatory variability. It explores a multi-speaker modelling approach based on two levels: statistically-based linear articulatory models, which capture the speaker-specific articulatory variability on the one hand, are in turn controlled by a speaker model, which captures the inter-speaker variability on the other hand. A low dimensionality speaker model is obtained by taking advantage of the inter-speaker correlations between morphology and strategy. To validate this approach, contours of the vocal tract articulators were manually segmented on midsagittal MRI data recorded from 11 French speakers uttering 62 vowels and consonants. Using these contours, multi-speaker models with 14 articulatory components and two morphology and strategy components led to overall variance explanations of 66%–69% and root-mean-square errors of 0.36–0.38 cm obtained in leave-one-out procedure over the speakers. Results suggest that inter-speaker variability is more related to the morphology than to the idiosyncratic strategies and illustrate the adaptation of the articulatory components to the morphology.Speech communication relies on articulatory and acoustic codes shared between speakers and listeners despite inter-individual differences in morphology and idiosyncratic articulatory strategies. This study addresses the long-standing problem of characterizing and modelling speaker-independent articulatory strategies and inter-speaker articulatory variability. It explores a multi-speaker modelling approach based on two levels: statistically-based linear articulatory models, which capture the speaker-specific articulatory variability on the one hand, are in turn controlled by a speaker model, which captures the inter-speaker variability on the other hand. A low dimensionality speaker model is obtained by taking advantage of the inter-speaker correlations between morphology and strategy. To validate this approach, contours of the vocal tract articulators were manually segmented on midsagittal MRI data recorded from 11 French speakers uttering 62 vowels and consonants. Using these contours, multi-speaker mode...

International audience; Speech production can be analysed in terms of universal articulatory-acoustic phonemic units shared between speakers. However, speakers’ morphological differences and idiosyncratic articulatory strategies lead to large inter-speaker articulatory variability. Relationships between strategy and morphology have already been pinpointed in the literature. This study aims thus at generalising existing results on a larger database for the entire vocal tract (VT) and at quantifying phoneme-specific inter-speaker articulatory invariants. Midsagittal MRI of 11 French speakers for 62 vowels and consonants were recorded and VT contours manually edited. A procedure of normalisation of VT contours between speakers, based on principal component analysis of mean VT contours, led to an overall reduction of inter-speaker VT contours variance of 84%. On the opposite, the sagittal function (i.e. the transverse sagittal distance along the VT midline), which is the main determinant of the acoustic output, had an overall amplitude variance decrease of only 18%, suggesting that the speakers adapt their strategy to their morphology to achieve proper acoustic goals. Moreover, articulatory invariants were identified on the sagittal variance distribution along the VT as the regions with lower variability. These regions correspond to the classical places of articulation and are associated with higher acoustic sensitivity function levels.

International audience; In this paper, we describe a comparison of the acoustic characteristics of one-dimensional and three-dimensional models of vocal tracts with nasal coupling. One-dimensional acoustic propagation is computed using an electric analog model. A finite element method is used for three-dimensional acoustic simulation. The comparison of these two approaches involves the vocal-tract shape of two subjects, one Japanese male and one French male pronouncing the vowel /a/ in their native language. Results show that the pole/zero pairs ascribed to the nasal coupling for both simulations appeared at almost the same frequency, at least below 2 kHz. Little difference between the one-dimensional and three-dimensional simulations in the transfer functions for the French subject is observed, since the three-dimensional mesh for the French subject is smoother. An extra pole exists in the transfer function of the three-dimensional model for the Japanese subject, possibly caused by the asymmetric structure of the laryngeal cavity. In the three-dimensional distribution of the active sound intensity vectors for the French subject, sound energy fluxes circulate between oral and nasal cavities coupled in the vicinity of the lips and nostrils.

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International audience; In the context of patient-specific 3D bone reconstruction, enhancing the surface with cortical thickness (COT) opens a large field of applications for research and medicine. This functionality calls for database analysis for better knowledge of COT. Our study provides a new approach to reconstruct 3D internal and external cortical surfaces from computer tomography (CT) scans and analyses COT distribution and variability on a set of asymptomatic femurs. The reconstruction method relies on a short (∼5 min) initialisation phase based on 3D reconstruction from biplanar CT-based virtual X-rays and an automatic optimisation phase based on intensity-based cortical structure detection in the CT volume, the COT being the distance between internal and external cortical surfaces. Surfaces and COT show root mean square reconstruction errors below 1 and 1.3 mm. Descriptions of the COT distributions by anatomical regions are provided and principal component analysis has been applied. The first mode, 16–50% of the variance, corresponds to the variation of the mean COT around its averaged shape; the second mode, 9–28%, corresponds to a fine variation of its shape. A femur COT model can, therefore, be described as the averaged COT distribution in which the first parameter adjusts its mean value and a second parameter adjusts its shape.

International audience; Two major functions of the human vocal tract are feeding and speaking. As, ontogenetically and hylogenetically, feeding tasks precede speaking tasks, it has been hypothesised that the skilled movements of the orofacial articulators specific to speech may have evolved from feeding functions. Our study explores this hypothesis by proposing an original methodological approach. Vocal tract articulatory measurements on two male subjects have been recorded for speech and feeding by electromagnetic articulography. Two guided Principal Component Analysis (PCA) articulatory models of the jaw/tongue system have been built for speech and feeding tasks. The two articulatory models show similar reconstruction accuracy. The speech and feeding articulations have been reconstructed respectively from feeding and speech raw PCA models. Root mean square reconstruction errors show better capacity of the feeding model to be generalised to the other set of articulations than the speech model. Our study suggests therefore that the tested hypothesis cannot be excluded on articulatory grounds for our two cases and brings a new methodology into the discussion of the ontogenetic and phylogenetic origins of speech.

La fin du XXe et le tout début de ce siècle révèlent une véritable réarticulation des recherches dans le domaine de l’émergence de la parole et du langage. Le naturalisme, qui est au centre de cette approche, se propose de décrire les relations entre la biologie (au sens très large du terme) d’une part, la parole et le langage, d’autre part, par une accumulation d’hypothèses, de données et de preuves formulées et établies grâce à de multiples collaborations interdisciplinaires. Comme pour les travaux sur l’origine de l’Homme (la découverte d’un nouveau fossile entraînant souvent une remise en question des théories précédentes), on assiste à un foisonnement théorique qui entraîne parfois des développements très hypothétiques, s’appuyant sur des résultats fragiles et sur trop peu de données, proposés dans des disciplines connexes mais non maîtrisées ou trop simplifiées. C’est pourquoi les bilans réguliers, les mises en perspectives critiques ne nous semblent pas superflus.Dans un premier temps nous proposerons une classification qui permet une lecture des différentes théories proposées depuis un demi-siècle (théorie push-pull). Dans l’état actuel des connaissances, il n’est pas possible d’inférer quand nos ancêtres, voire nos lointains ont acquis la faculté de langage et de parole : le contrôle des articulateurs, la coordination entre le larynx et le conduit vocal, la phonologie, la syntaxe, la sémantique et la récursivité. Parmi les questions qui se posent, il en est une qui reste sans réponse : pourquoi notre espèce est actuellement la seule à posséder langue et parole ? De nombreuses questions font partie des problèmes mal posés, comme le sont les questions du type: Quelle(s) langue(s) parlaient nos prédécesseurs ? Possédaient-ils une langue unique ? En effet, on ne dispose pas (pour le moment) de suffisamment de données pour pouvoir y répondre. Peut-être même que ces questions ne trouveront pas de solution. Actuellement, il est quand même possible de répondre à la question suivante : si nous supposons que nos ancêtres (et cousins lointains) contrôlaient leur larynx et leur conduit vocal de la même manière que les Hommes actuels, est-ce que la géométrie de leur conduit leur permettaient de produire les structures sonores qui sont pratiquement présentes dans toutes les langues du monde ?Nous présenterons ensuite nos travaux qui participent à la nouvelle réarticulation avec une approche véritablement axée sur la pluridisciplinarité. Ils s’inscrivent dans le domaine des relations entre la morphologie des organes de la production de la parole et son contrôle. Nous présentons de nouveaux résultats concernant la croissance du conduit vocal de la naissance à l’âge adulte puis des reconstructions du conduit vocal pour des fossiles qui couvrent la période de 10.000 ans à un million et demi d’années BP (Before Present). À partir du crâne, de la mandibule et des vertèbres cervicales nous essaierons de manière plausible (1) de localiser l’os hyoïde, support de la langue, et la position de la glotte, (2) de reconstituer un conduit vocal, à l’aide d’un modèle articulatoire, (3) d’induire les possibilités acoustiques de tous ces conduits. En combinant phylogenèse et ontogenèse il est possible de représenter l’anatomie du tractus en synthétisant deux remodelages qui renvoient à l’ontogenèse et à la phylogenèse. Nous montrerons que tous ces conduits ont les mêmes potentialités acoustiques, ils peuvent produire les voyelles /i a u/ qui sont pratiquement présentes dans toutes les langues du monde : un triangle à l’intérieur duquel se situent toutes les autres voyelles. Quand aux consonnes les plus fréquentes /p t k/, /b d g/ elles sont aussi à la portée de tous ces conduits vocaux à partir de gestes de fermeture dans des régions précises (lèvres, zone alvéodentale, zone vélaire). De nouvelles pistes de recherche sont proposées qui tendraient à montrer qu’il y a vraisemblablement plusieurs centaines de milliers, voire plusieurs millions d’années que le conduit vocal présente une morphologie favorable à l’émergence et à la production de la parole. Un cadre est posé dans lequel les capacités orofaciales nécessaire à la parole pourraient être reliées au mécanisme précurseur d’ingestion (mastication-déglutition).The end of the XXth century and the beginning of this century saw a reorganization of the researches in the field of speech and language emergence (SLE). Naturalism is the kernel of this new approach. It consists in describing the relations between biological aspects (in every sense of the word) on the one hand and speech and language, on the other hand, by an accumulation of hypotheses and evidence derived from a huge range of data collected thanks to interdisciplinary collaborations.As is the case for researches on the origin of Man, a theoretical profusion of hypotheses has arisen which sometimes leads to very hypothetical developments, based on fragile results and on too little data, and proposed in related but not fully mastered or too much simplified disciplines. This is why regular critical overviews do not seem superfluous. First, we propose a classification (push and pull theory) that provides a new reading of the various theories which have been proposed for half a century. In the present state of knowledge it is not possible to infer when our ancestors acquired the FacultyofSpeechandLanguageandSpeech: control of speech articulators, coordination between larynx and vocal tract, phonology, syntax, semantic and recursivity. Among old unsolved questions: Why is our species alone in having speech and language? Many others questions are (for the moment?) ill posed problems: we do not have sufficiently data to answer. Perhaps these questions will remain unsolved. But we think that the following question can be solved: If we suppose that our ancestors (and distant cousins) controlled their larynx and vocal tract in the same way as present-day humans, did the geometry of their vocal tract allow them to produce the universal sound structures of the languages spoken today? We analyzed 31 skulls from now to 1.5 Ma (millions years) BP (Before Present) for fossil hominids available at the Muséedel’Homme in Paris or in the literature: (1) 10-30 ka BP: modern humans: Paleolithic; (2) 90-200 ka BP: anatomically modern humans; (3) 45-90 ka BP: Neanderthals; (4) 1.5 Ma BP: Homoergaster; These skulls are all well kept and possess a jaw in the majority of cases but the vertebral column has been reconstituted. We attempt to: (1) Localize hyoid bone and then glottis position; (2) Reconstitute a vocal tract model in a plausible way using an articulatory model; (3) Quantify the acoustic capabilities of this reconstituted vocal tract. For this purpose, we combine phylogenesis and ontogenesis. We are in a position to state that our ancestors and distant cousins were equipped with a vocal tract that could produce the same variety of vowel sounds as we can today: the vowels /i a u/. The vocal tract morphology has been favorable to the emergence and production of speech since several hundreds of thousands of years. But how to know to what extent they mastered the control skills needed to produce speech? New lines of research are proposed in which orofacial abilities necessary to the emergence of speech are linked to a precursor mechanism dedicated to feeding (masticating-swallowing movements).