Acoustic impacts of geometric approximation at the level of velum and epiglottis on French vowels

International audienceIn this work we study the effect of the velum and epiglottis on speech production of five French vowels. Our purpose is to examine whether it is possible to simplify the geometry of the vocal tract in the framework of articulatory synthesis to achieve a simpler geometric description without changing the acoustic properties. In the present study, we use MRI to acquire the 3D shape of the vocal tract with simultaneous recording of the speech signal. The geometric two-dimensional shape derived from these data was used as an input of numerical acoustic simulations. The geometrical shape was edited at the level of epiglottis and velum (with or without epiglottis, with or without a constant wall approximation at velum) and the spectra obtained via numerical acoustic simulations were compared with those obtained from audio recordings. This allows the impact of these articulators and geometrical simplifications to be assessed

Synchronisation vocale et mouvement compensé en reconstruction pour une ciné IRM de la parole

National audienceL’imagerie dynamique du conduit vocal permet d’étudier et de modéliser la production de laparole. La durée moyenne de chaque son est d’environ 80 ms. Lemouvement de chaque articulateur, en particulier la langue, doit être mesuréavec suffisamment de précision. Actuellement la fluoroscopie à rayon X estutilisée cliniquement. L’IRM temps réel permet la visualisation directe desmouvements articulatoires [1] mais reste limitée en résolution. Lasynchronisation de l’IRM par un système acoustique est possible [2] maisnécessite l’exécution de mouvements articulatoires avec une parfaitereproductibilité. Dans ce travail nous proposons un dispositif optimisé pour laréalisation d’une imagerie dynamique IRM de la parole avec une hauterésolution spatiale et temporelle. Il s’appuie sur l’utilisation conjointe d’unmicrophone compatible IRM enregistrant la parole pendant l’acquisition IRMet d’une reconstruction d’images synchronisées a posteriori incluant unecompensation du mouvement. Cette reconstruction permet une prise encompte de la variabilité de répétition de la phrase lors de l’acquisition

Free-breathing myocardial T2 measurements at 1.5T

POSTER PRESENTATIONInternational audienc

Sound synchronization and motion compensated reconstruction for speech Cine MRI

International audienceDynamic imaging of the vocal tact is important for modeling speechthrough the acoustic-articulatory relation. The average duration of each sound isabout 80ms. Movements of each articulator, in particular the tongue, should becaptured with sufficient precision. Current clinical techniques use X-ray videofluoroscopy which involves ionizing radiation. Real-time MRI allows direct recordingof speech motion [1] but is intrinsically limited in terms of resolution and SNR.Synchronization of MRI with an acoustic device is possible [2] but requires motion ofvocal system to be highly reproducible. In this work we propose an optimized setupfor achieving dynamic MRI of speech with high spatial and temporal resolution basedon a combination of: an MR-compatible acoustic device allowing simultaneousrecording of speech during MRI; and a retrospectively gated, motion-compensatedimage reconstruction that can deal with the variability of the subject repeating thesame sentence over the acquisition

Speech Cine SSFP with optical microphone synchronization and motion compensated reconstruction

International audienceDynamic imaging of the vocal tact is important for modeling speechthrough the acoustic-articulatory relation. The average duration of each sound isabout 80ms. Movements of each articulator, in particular the tongue, should becaptured with sufficient precision. Current clinical techniques use X-ray videofluoroscopy which involves ionizing radiation. Real-time MRI allows direct recordingof speech motion [1] but is intrinsically limited in terms of resolution and SNR.Synchronization of MRI with an acoustic device is possible [2] but requires motion ofvocal system to be highly reproducible. In this work we propose an optimized setupfor achieving dynamic MRI of speech with high spatial and temporal resolution basedon a combination of: an MR-compatible acoustic device allowing simultaneousrecording of speech during MRI; and a retrospectively gated, motion-compensatedimage reconstruction that can deal with the variability of the subject repeating thesame sentence over the acquisition

Vocal tract sagittal slices estimation from MRI midsagittal slices during speech production of CV

International audienc

Synthesize MRI vocal tract data during CV production

International audienceA set of rtMR image transformations across time is computed during the production of CV that is afterwards applied to a new speaker in order to synthesize his/her CV pseudo rtMRI data. Synthesized images are compared with the original ones using image cross-correlation. 2 Purpose To be able to enlarge MRI speech corpus by synthesizing data

A Multimodal Real-Time MRI Articulatory Corpus of French for Speech Research

International audienceIn this work we describe the creation of ArtSpeechMRIfr: a real-time as well as static magnetic resonance imaging (rtMRI, 3D MRI) database of the vocal tract. The database contains also processed data: denoised audio, its phonetically aligned annotation, articulatory contours, and vocal tract volume information , which provides a rich resource for speech research. The database is built on data from two male speakers of French. It covers a number of phonetic contexts in the controlled part, as well as spontaneous speech, 3D MRI scans of sustained vocalic articulations, and of the dental casts of the subjects. The corpus for rtMRI consists of 79 synthetic sentences constructed from a phonetized dictionary that makes possible to shorten the duration of acquisitions while keeping a very good coverage of the phonetic contexts which exist in French. The 3D MRI includes acquisitions for 12 French vowels and 10 consonants, each of which was pronounced in several vocalic contexts. Ar-ticulatory contours (tongue, jaw, epiglottis, larynx, velum, lips) as well as 3D volumes were manually drawn for a part of the images

Analyse de la fonction ventriculaire droite

Le ventricule droit (VD) fut longtemps oublié par les cardiologues mais l'expérience a montré qu'il conditionne le pronostic des patients dans de nombreuses situations cliniques et que l'évaluation de sa fonction est un élément diagnostique majeur lorsqu'une pathologie du VD est suspectée. Après une revue des différentes méthodes d'évaluation de la fonction ventriculaire droite, cette thèse explore tout d'abord les limites des deux méthodes d'évaluation du VD les plus répandues (IRM et échographie) : Premièrement, les indices de contraction longitudinale en échographie ne permettent pas de dépister correctement les altérations de la fraction d'éjection dans la situation d'une surcharge volumétrique notamment. Deuxièmement, l'IRM en coupes petit-axe présente des difficultés importantes de délinéation de l'endocarde. Les principaux écarts de contours entre deux observateurs concernent l'infundibulum pour 40% et la valve tricuspide pour 40% également. Dans une troisième partie, nous proposons un indice géométrique simple à calculer lors d'un examen IRM et permettant de pré-sélectionner les patients nécessitant une étude précise du VD. Cet indice validé sur 340 patients réduit le temps opérateur de 35% sans entrainer d'erreur diagnostique. La dernière partie de cette thèse s'intéresse à la mesure de la vitesse tissulaire du myocarde et aux indices fonctionnels qui en dérivent. Cette mesure nécessite une haute résolution temporelle qui peut être atteinte en IRM en respiration libre au prix d'une augmentation de la durée d'acquisitionThe right ventricle (RV) has been neglected for a long time by cardiologists. Only recently, it has been pointed out as yielding pronostic or diagnostic value in numerous clinical situations. This thesis, after a review of the different methods used to assess the right ventricular function, stresses the limitations of the two most used methods to assess RV function: 1) Long-axis contraction indices fail to predict ejection fraction in a volumetric overload situation. 2) Short-axis MRI relies upon a rather difficult manual contouring of the endocardium. The main variation in this contouring occurs in the infundibulum (40%) and in the basal part around the tricuspid valve (40%). Then, we propose a novel geometric indice, easy to compute during a MRI examination and aimed to select the patients needing an accurate RV study. This index was validated within 340 patients and reduced the operator time of 35% without inducing any diagnostic error. The last part of this thesis concerns tissue phase-mapping. High temporal resolution is the key point for the accuracy of myocardial velocities and can be achieved by a simple averaging during free-breathing at the expense of longer acquisitionsMETZ-SCD (574632105) / SudocNANCY1-Bib. numérique (543959902) / SudocNANCY2-Bibliotheque electronique (543959901) / SudocNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF