Visualisation of the Vocal-Tract Shape for a Computer-Based Speech Training System for the Hearing-Impaired

摘要

A computer-based tool for visualisation of the vocal-tract, during speech articulation, by means of a midsagittalview of the human head has been designed and developed. The vocal tract graphics are generated using a new approachthat is based on estimating both the area functions and the formant frequencies from the acoustic speech signal.First, it is assumed that the speech production process is an autoregressive model. Using a linear prediction analysis, thevocal tract area functions and the first three formants are estimated. The estimated area functions are then mapped to correspondingmid-sagittal distances and displayed as 2D vocal tract lateral graphics. The mapping process is based on asimple numerical algorithm and an accurate reference grid derived from x-rays for the pronunciation of a number Englishvowels uttered by different speakers. To compensate for possible errors in the estimated area functions due to variation invocal tract length between speakers, the first two sectional distances are determined by the three formants. Experimentalresults show high correlation with x-ray data and the PARAFAC analysis. The tool also displays other speech parametersthat are closely related to the production of intelligible speech and hence would be useful as a visual feedback aid forspeech training of hearing–impaired individuals and children with speech impediment.