### 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.]