Audiovisual to area and length functions inversion of human vocal tract

This paper proposes a multimodal approach to estimate the area function and the length of the vocal tract of oral vowels. The method is based on an iterative technique consisting in deforming an initial area function so that the output acoustic vector matches a specified target. The chosen acoustic vector is the formant frequency pattern. In order to regularize the ill-problem, several constraints are added to the algorithm. First, the lip termination area is estimated via a facial capture software. Then, the area function is constrained in such a way that it does not get too far from a neutral position, and it does not change too quickly from a temporal frame to the next, when dealing with dynamic inversion. The method proves to be efficient to approximate the area function and the length of the vocal tract for oral french vowels, both in static and dynamic configurations.