ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

3aSC2. A three-dimensional solution of the wave equation in a model of the vocal tract.

Fariborz Alipour

Brad H. Story

Dept. of Speech Path. and Audiol. & Natl. Ctr. for Voice and Speech, The Univ. of Iowa, Iowa City, IA 52242

The wave equation was solved in a cylindrical coordinate system for models of the vocal tract corresponding to vowels, /a/, /i/, and /u/. A straight cylindrical model of vocal tract was built upon area function data for each vowel. Using boundary fitted coordinates, the vocal tract shape and its boundary conditions were simplified to a straight tube. However, this simplification in geometry resulted in a complicated wave equation in the new coordinate system. The transformed wave equation was discretized in space over a 91x21 grid and solved in time using a finite difference method. Preliminary results indicate that pressure contours are typically planar, however, higher-order mode propagation is possible with this model. The results of the model have been compared and validated against the open--open and closed--open uniform tubes with good accuracy. The predicted frequency response of this model was also compared with a wave-reflection type of model. [Work supported by NIDCD Grant No. DC00831-04.]