ASA 125th Meeting Ottawa 1993 May

5aSP14. Using a new model of vocal-tract midsagittal profile to area-function conversion to constrain an optimization algorithm for the articulatory-acoustic inversion of fricative consonants.

Pierre Badin

Denis Beautemps

Rafael Laboissiere

Inst. de la Commun. Parlee, 46 Ave. Felix Viallet, 38031 Grenoble Cedex, France

An extension of Heinz and Stevens' (alpha)(beta) model [Proc. of 5th Int. Congr. Acoust. A44 (1965)], where (alpha) continuously depends on both midsagittal distance and VT position (along the midline), has been optimized from x-ray cineradiographs and formant frequencies obtained on a set of vowels and fricatives uttered by a subject. The purpose of the study was to recover the midsagittal function (a vector of 50 midsagittal distances) of fricative consonants from the measured formant frequencies, in [VCV] contexts. In order to reduce the excess degrees of freedom of this ill-posed problem, the proposed model has been used as a major way to constrain an optimization algorithm based on a gradient descent technique. The gradient of the error between actual and desired formant values is computed through a back-propagation network implementing both sagittal-to-area conversion and acoustic wave propagation. Preliminary results are presented and discussed. [Work partly supported by CNRS & CEC-ESPRIT project SPEECH MAPS.]