Contributions of vocal tract shape to voice quality

Abstract

Three-dimensional vocal tract shapes and consequent area functions representing the vowels [i a u] have been acquired from one male and one female subject using MRI. The two subjects were highly trained professional singers, and both were adept at manipulation of vocal tract shape to alter voice quality. Each vowel was performed four times, each with one of the four voice qualities: typical speech, yawny, twangy, and high pitched classical singing. The purpose of the study was to determine how the vocal tract shape can be manipulated to alter vocal quality while retaining a desired phonetic quality. Relative to typical speech, the resulting area functions show, in general, that the lower pharynx is widened for both the yawny and classical singing productions and narrowed for the twangy voice type. Additionally, the yawny and classical singing qualities have widened oral cavities while the twangy quality shows decreased oral cavity area. This contrasts, however, with the lip opening where the twangy quality shows larger area than any of the other three qualities.