Document Type

Article

Publication Date

4-14-2008

Journal / Book Title

The Journal of the Acoustical Society of America

Abstract

Nonlinear source-filter coupling has been demonstrated in computer simulations, in excised larynx experiments, and in physical models, but not in a consistent and unequivocal way in natural human phonations. Eighteen subjects (nine adult males and nine adult females) performed three vocal exercises that represented a combination of various fundamental frequency and formant glides. The goal of this study was to pinpoint the proportion of source instabilities that are due to nonlinear source-tract coupling. It was hypothesized that vocal fold vibration is maximally destabilized when F0 crosses F1, where the acoustic load changes dramatically. A companion paper provides the theoretical underpinnings. Expected manifestations of a source-filter interaction were sudden frequency jumps, subharmonic generation, or chaotic vocal fold vibrations that coincide with F0 - F1 crossovers. Results indicated that the bifurcations occur more often in phonations with F0 - F1 crossovers, suggesting that nonlinear source-filter coupling is partly responsible for source instabilities. Furthermore it was observed that male subjects show more bifurcations in phonations with F0 - F1 crossovers, presumably because in normal speech they are less likely to encounter these crossovers as much as females and hence have less practice in suppressing unwanted instabilities.

DOI

10.1121/1.2832339

Rights

Copyright (2008) Acoustical Society of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.

Published Citation

Titze, I., Riede, T., & Popolo, P. (2008). Nonlinear source–filter coupling in phonation: Vocal exercises. The Journal of the Acoustical Society of America, 123(4), 1902-1915.

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