The inverse problem for the vocal tract: Numerical methods, acoustical experiments, and speech synthesis

Abstract

Recent experiments on the estimation of vocal tract area functions from transient acoustical measurements at the lips are described. Since the theoretical basis for such measurements has been discussed earlier, the measurement technique and the numerical procedures used to estimate the area functions from the measurements are stressed. Measurements can be made and the area function computed and displayed .apprx. 18 times/s. Such a display allows the shape of the vocal tract to be visualized as the positions of articulators are changed. This display could form the basis of a visual aid for the improvement of the speech of proundly deaf persons. Intelligible though not yet high quality speech from several sentence-length sequences of measured area functions was synthesized. This may be the 1st instance of continuous speech synthesized from direct measurements of area functions.