Using phonetic constraints in acoustic-to-articulatory inversion

The goal of this work is to recover articulatory information from the speech signal by acoustic-to-articulatory inversion. One of the main difficulties with inversion is that the problem is underdetermined and inversion methods generally offer no guarantee on the phonetical realism of the inverse solutions. A way to adress this issue is to use additional phonetic constraints. Knowledge of the phonetic caracteristics of French vowels enable the derivation of reasonable articulatory domains in the space of Maeda parameters: given the formants frequencies (F1,F2,F3) of a speech sample, and thus the vowel identity, an "ideal" articulatory domain can be derived. The space of formants frequencies is partitioned into vowels, using either speaker-specific data or generic information on formants. Then, to each articulatory vector can be associated a phonetic score varying with the distance to the "ideal domain" associated with the corresponding vowel. Inversion experiments were conducted on isolated vowels and vowel-to-vowel transitions. Articulatory parameters were compared with those obtained without using these constraints and those measured from X-ray data

STM2209-STM2208 (opvAB): A Phase Variation Locus of Salmonella enterica Involved in Control of O-Antigen Chain Length

STM2209 and STM2208 are contiguous loci annotated as putative protein-coding genes in the chromosome of Salmonella enterica. Lack of homologs in related Enterobacteria and low G+C content suggest that S. enterica may have acquired STM2209-STM2208 by horizontal transfer. STM2209 and STM2208 are co-transcribed from a promoter upstream STM2209, and their products are inner (cytoplasmic) membrane proteins. Analysis with the bacterial adenylate cyclase two-hybrid system suggests that STM2209 and STM2208 may interact. Expression of STM2209-STM2208 is subjected to phase variation in wild type Salmonella enterica serovar Typhimurium. Switching frequencies in LB medium are 6.1×10−5 (OFF→ON) and 3.7×10−2 (ON→OFF) per cell and generation. Lack of DNA adenine methylation locks STM2209-STM2208 in the ON state, and lack of the LysR-type factor OxyR locks STM2209-STM2208 in the OFF state. OxyR-dependent activation of STM2209-STM2208 expression is independent of the oxidation state of OxyR. Salmonella cultures locked in the ON state show alteration of O-antigen length in the lipopolysaccharide, reduced absorption of bacteriophage P22, impaired resistance to serum, and reduced proliferation in macrophages. Phenotypic heterogeneity generated by STM2209-STM2208 phase variation may thus provide defense against phages. In turn, formation of a subpopulation unable to proliferate in macrophages may restrain Salmonella spread in animal organs, potentially contributing to successful infection

Compact representations of the articulatory-to-acoustic mapping

International audienceArticulatory codebooks are very often used to represent the articulatory-to-acoustic mapping. They thus need to be compact while offering a very good acoustic precision. This paper presents a method of articulatory codebook construction more general than that of Ouni in the sense that the articulatory-to-acoustic mapping is approximated by multivariable polynomials. The second major contribution concerns the subdivision process which finds out the most efficient subdivision, i.e. that which minimizes the size of the codebook while guarantying a very good acoustic precision. Experiments carried out show that the size of the codebook can be divided by a factor of 20, and simultaneously, the acoustic precision can improved by a factor of 2 by using second order polynomials together with this new construction strategy

A study on sound source apparent shape and wideness

Proceedings of the 9th International Conference on Auditory Display (ICAD), Boston, MA, July 7-9, 2003.This work is intended as an initial investigation into the perception of wideness and shape of sound sources. A method that employs multiple uncorrelated point sources is used in order to form ``sound shapes''. Several experiments were carried out in which, after some initial training, subjects were asked to indentify the shapes that were being played. Results indicate that differences in vertical and horizontal source wideness are easily perceived and scenes that use broad sound sources to represent normally large sound objects are selected 70% of the time over point source versions. However, shape identification was found to be more ambiguous except for certain types of signals where results were above statistical probability. The work indicates that shape and wideness of sound sources could be effectively used as extra cues in virtual auditory displays and generally improve the realism of virtual 3D sound scenes. This work was performed as a Core Experiment within the MPEG Audio Subgroup with the intention of possible integration of source wideness into MPEG-4 AudioBIFS

Improving the Sampling of the Null Space of the Acoustic-to-Articulatory Mapping

International audienceThis paper presents a new method for sampling the null space of the acoustic-to-articulatory mapping, which is considerably faster and more accurate than the previous method presented by Ouni and Laprie. This is achieved by using a simple stochastic exploration of the articulatory space instead of complex linear programming techniques. This new method allows for a much faster and more accurate inversion process

Inversion acoustique-articulatoire en utilisant des contraintes phonétiques

Le but de l'inversion acoustique articulatoire est d'obtenir la position des articulateurs à partir du signal de parole. L'une des difficultés majeures de l'inversion est qu'une infinité de formes de conduits peut donner un même spectre de parole. Une façon de réduire cette difficulté est de contraindre davantage le problème, en utilisant par exemple des contraintes d'ordre visuel (on suppose connaître en plus du signal de parole, la position des articulateurs visibles ; ce qui peut se faire en utilisant une ou plusieurs caméras), ou d'ordre phonétique (les caractéristiques phonétiques des voyelles du Français sont connues, par exemple). Mais cette difficulté peut aussi se transformer en avantage : en permettant d'obtenir toutes les configurations du conduit vocal correspondant à un son donné, l'inversion fournit potentiellement un moyen d'étudier des stratégies compensatoires préservant l'acoustique. Nous montrerons comment l'utilisation de contraintes d'origine phonétique permet de réduire considérablement l'espace des solutions et d'améliorer la pertinence des solutions

Adjonction de contraintes visuelles pour l'inversion acoustique-articulatoire

The goal of this work is to investigate audiovisual-to-articulatory inversion. It is well established that acoustic-to-articulatory inversion is an under-determined problem. On the other hand, there is strong evidence that human speakers/listeners exploit the multimodality of speech, and more particularly the articulatory cues : the view of visible articulators, i.e. jaw and lips, improves speech intelligibility. It is thus interesting to add constraints provided by the direct visual observation of the speaker's face. Visible data were obtained by stereo-vision and enable the 3D recovery of jaw and lip movements. These data were processed to fit the nature of parameters of Maeda's articulatory model. Inversion experiments show that constraints on visible articulatory parameters enable relevant articulatory trajectories to be recovered and substantially reduce time required to explore the articulatory codebook

Inversion acoustique-articulatoire en utilisant des contraintes phonétiques

Textes issus des Journées fédératrices "Perturbations et réajustements, langue et langage" organisées à Haguenau en décembre 2004 par le Réseau des sciences cognitives du Grand Est, Cogniest, l'E.A. 1399 Linguistique, langues et paroles -LilPa...Le but de l'inversion acoustique articulatoire est d'obtenir la position des articulateurs à partir du signal de parole. L'une des difficultés majeures de l'inversion est qu'une infinité de formes de conduits peut donner un même spectre de parole. Une façon de réduire cette difficulté est de contraindre davantage le problème, en utilisant par exemple des contraintes d'ordre visuel (on suppose connaître en plus du signal de parole, la position des articulateurs visibles ; ce qui peut se faire en utilisant une ou plusieurs caméras), ou d'ordre phonétique (les caractéristiques phonétiques des voyelles du Français sont connues, par exemple). Mais cette difficulté peut aussi se transformer en avantage : en permettant d'obtenir toutes les configurations du conduit vocal correspondant à un son donné, l'inversion fournit potentiellement un moyen d'étudier des stratégies compensatoires préservant l'acoustique. Nous montrerons comment l'utilisation de contraintes d'origine phonétique permet de réduire considérablement l'espace des solutions et d'améliorer la pertinence des solutions