A 3D biomechanical vocal tract model to study speech production control: How to take into account the gravity?

This paper presents a modeling study of the way speech motor control can deal with gravity to achieve steady-state tongue positions. It is based on simulations carried out with the 3D biomechanical tongue model developed at ICP, which is now controlled with the Lambda model (Equilibrium-Point Hypothesis). The influence of short-delay orosensory feedback on posture stability is assessed by testing different muscle force/muscle length relationships (Invariant Characteristics). Muscle activation patterns necessary to maintain the tongue in a schwa position are proposed, and the relations of head position, tongue shape and muscle activations are analyzed

Use of a biomechanical tongue model to predict the impact of tongue surgery on speech production

This paper presents predictions of the consequences of tongue surgery on speech production. For this purpose, a 3D finite element model of the tongue is used that represents this articulator as a deformable structure in which tongue muscles anatomy is realistically described. Two examples of tongue surgery, which are common in the treatment of cancers of the oral cavity, are modelled, namely a hemiglossectomy and a large resection of the mouth floor. In both cases, three kinds of possible reconstruction are simulated, assuming flaps with different stiffness. Predictions are computed for the cardinal vowels /i, a, u/ in the absence of any compensatory strategy, i.e. with the same motor commands as the one associated with the production of these vowels in non-pathological conditions. The estimated vocal tract area functions and the corresponding formants are compared to the ones obtained under normal condition

Modeling the consequences of tongue surgery on tongue mobility

This paper presents the current achievements of a long term project aiming at predicting and assessing the impact of tongue and mouth floor surgery on tongue mobility. The ultimate objective of this project is the design of a software with which surgeons should be able (1) to design a 3D biomechanical model of the tongue and of the mouth floor that matches the anatomical characteristics of each patient specific oral cavity, (2) to simulate the anatomical changes induced by the surgery and the possible reconstruction, and (3) to quantitatively predict and assess the consequences of these anatomical changes on tongue mobility and speech production after surgery

3D tooth surface reconstruction

Master'sMASTER OF ENGINEERIN

A multilinear tongue model derived from speech related MRI data of the human vocal tract

We present a multilinear statistical model of the human tongue that captures anatomical and tongue pose related shape variations separately. The model is derived from 3D magnetic resonance imaging data of 11 speakers sustaining speech related vocal tract configurations. The extraction is performed by using a minimally supervised method that uses as basis an image segmentation approach and a template fitting technique. Furthermore, it uses image denoising to deal with possibly corrupt data, palate surface information reconstruction to handle palatal tongue contacts, and a bootstrap strategy to refine the obtained shapes. Our evaluation concludes that limiting the degrees of freedom for the anatomical and speech related variations to 5 and 4, respectively, produces a model that can reliably register unknown data while avoiding overfitting effects. Furthermore, we show that it can be used to generate a plausible tongue animation by tracking sparse motion capture data

Detection of severe obstructive sleep apnea through voice analysis

tThis paper deals with the potential and limitations of using voice and speech processing to detect Obstruc-tive Sleep Apnea (OSA). An extensive body of voice features has been extracted from patients whopresent various degrees of OSA as well as healthy controls. We analyse the utility of a reduced set offeatures for detecting OSA. We apply various feature selection and reduction schemes (statistical rank-ing, Genetic Algorithms, PCA, LDA) and compare various classifiers (Bayesian Classifiers, kNN, SupportVector Machines, neural networks, Adaboost). S-fold crossvalidation performed on 248 subjects showsthat in the extreme cases (that is, 127 controls and 121 patients with severe OSA) voice alone is able todiscriminate quite well between the presence and absence of OSA. However, this is not the case withmild OSA and healthy snoring patients where voice seems to play a secondary role. We found that thebest classification schemes are achieved using a Genetic Algorithm for feature selection/reduction

Activations musculaires et mouvements linguaux : modélisation en parole naturelle et pathologique

The purpose of the work presented in this manuscript is the development, in the long run, of some interactive software for tongue surgery, based on a three-dimensional biomechanical model of the tongue, allowing the evaluation of the consequences of some surgery on tongue mobility and supporting the planning and the per-operational guidance of the surgical gesture. The studies led to date aim at studying the feasibility of such a tool. The first part of this thesis is devoted to a thorough description of the model used. After the presentation of the vocal tract anatomy and of the clinical context, the model geometry is described with precision (internal structure of the tongue model and representation of the bony and soft structures of the vocal tract). The assumptions carried out for biomechanical modelling are introduced as well as the motor control scheme based on the lambda model of the equilibrium-point hypothesis. The extraction of the vocal tract area function is then presented with the model of speech synthesis. The second part is centred on the results obtained for natural and pathological speech. Our simulations showed the ability of our model to generate the oral vowels of French, with acoustic characteristics close to the values generally observed and satisfactory tongue shapes. Similar simulations are also presented for two cases of tongue surgery: a hemiglossectomy and a widened mouth floor resection.Les travaux présentés dans ce mémoire ont pour but, à long terme, l'élaboration d'un outil interactif pour la chirurgie linguale, basé sur un modèle biomécanique tridimensionnel de la langue, et permettant à la fois d'évaluer les conséquences d'une chirurgie sur la mobilité linguale et de favoriser le planning et le guidage per-opératoire du geste chirurgical. Les études conduites à ce jour visent à étudier la faisabilité d'un tel outil.La première partie de ce mémoire est consacrée à une description approfondie du modèle utilisé. Après une présentation de l'anatomie du conduit vocal et du contexte clinique, la géométrie du modèle est décrite avec précision (structure interne du modèle de langue et représentation des structures osseuses et molles du conduit vocal) ainsi que les hypothèses effectuées tant sur le plan de la modélisation biomécanique à l'aide d'un modèle hyperélastique que du contrôle moteur basé sur le modèle lambda du point d'équilibre. L'extraction de la filière aérique est alors introduite de même que le modèle de synthèse utilisé.La seconde partie est centrée sur les résultats obtenus en parole naturelle et en parole pathologique. Les simulations réalisées ont permis de montrer que ce modèle était capable de générer les voyelles orales du français, avec des caractéristiques acoustiques proches des valeurs généralement observées et des formes de langue satisfaisantes. Des simulations similaires sont également présentées pour deux cas de chirurgie linguale : une hémiglossectomie et une résection élargie du plancher buccal

Between cultures: Travel writing, identity, and the global novel

This thesis consists of a work of experimental writing and a critical commentary. Drawing on practice-led research, it studies the exclusionary nature of travel writing with regards to women and migrants and destabilises certain ideas about genre, informed by outdated and restrictive perceptions of identity and who gets to write about travel, which perpetuate exclusionary realities. The novel explores the relationship between the genre1 of travel writing and how we articulate our own identity2 , through three generations of women’s travels. Travels here refers to ‘the written account of such journeys’3 in spatial, temporal, and metaphorical terms, glimpsing at internal journeys and changing perceptions about identity, through the stories we retain and the ones we choose to forget. A physical journey also, across multiple countries; over a period that ranges from the colonial era to the not-to-distant future. A metaphorical journey finally, which explores the result of the confrontation between the subjective experience of migration (documented as travel writing) and the imagined sense of identity (inherited from curated memories through history, literature and family myths.) The result is a collection of fragmented texts which mirror the gradual dissolution of a linear and chronological perception of who we are in favour of a re-articulation of self in relation to the present experience alone

A biomechanical model of cardinal vowel production: muscle activations and the impact of gravity on tongue positioning

International audienceA 3D biomechanical model of the tongue and the oral cavity, controlled by a functional model of muscle force generation (-model of the equilibrium point hypothesis) and coupled with an acoustic model, was exploited to study the activation of the tongue and mouth floor muscles during the production of French cardinal vowels. The selection of the motor commands to control the tongue and the mouth floor muscles was based on literature data, such as electromyographic (EMG), electropalatographic (EPG) and cineradiographic data. The tongue shapes were also compared to data obtained from the speaker used to build the model. 3D modeling offered the opportunity to investigate the role of the transversalis, in particular its involvement in the production of high front vowels. It was found, with this model, to be indirect via reflex mechanisms due to the activation of surrounding muscles, not voluntary. For vowel /i/, local motor command variations for the main tongue muscles revealed a non-negligible modification of the alveolar groove in contradiction to the saturation effect hypothesis, due to the role of the anterior genioglossus. Finally, the impact of subject position (supine or upright) on the production of French cardinal vowels was explored and found to be negligible