  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.
