On sensitivity of vocal tract area functions

The Wakita´s area functions based on the linear prediction model, assume the vocal tract to be lossless. Due to this assumption, the actual non-zero losses and additional errors in estimating them affect the area functions significantly. To quantify these effects, the sensitivity of area functions to perturbations in band widths and formants is systematically studied and their relative importance is presented. To overcome the effects of errors in bandwidth estimation, a modification for the area function is proposed. The effectiveness of these modified area functions is demonstrated by a vowel recognition test using both Wakita´s area functions and the modified area functions.