Physics of Voice Production
Neuromuscular control of voice
Production and perception
Mechanical models of voice production
Computational models of voice production
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Causal relation between voice production and quality
At present, it is not well understood how changes in vocal fold biomechanics correspond to changes
in voice quality. Understanding such cross-domain links from physiology to acoustics to perception
in the “speech chain” is of both theoretical and clinical importance. This study investigates links
between changes in body layer stiffness, which is regulated primarily by the thyroarytenoid
muscle, and the consequent changes in acoustics and voice quality under left-right symmetric and
asymmetric stiffness conditions. Voice samples were generated using three series of two-layer
physical vocal fold models, which differed only in body stiffness. Differences in perceived voice
quality in each series were then measured in a “sort and rate” listening experiment. The results
showed that increasing body stiffness better maintained vocal fold adductory position, thereby
exciting more high-order harmonics, differences that listeners readily perceived. Changes to the
degree of left-right stiffness mismatch and the resulting left-right vibratory asymmetry did not
produce perceptually significant differences in quality unless the stiffness mismatch was large
enough to cause a change in vibratory mode. This suggests that a vibration pattern with left-right
asymmetry does not necessarily result in a salient deviation in voice quality, and thus may not
always be of clinical significance.
Zhang, Z., Kreiman, J., Gerratt, B.R., Garellek, M. (2013). Acoustic and perceptual effects of changes in body layer stiffness in symmetric and asymmetric vocal fold models, J. Acoust. Soc. Am., 133, 453-462. [pdf] [link]
Signorello, R., Zhang, Z., Gerratt, B., Kreiman, J. (2016). Impact of vocal tract resonance on the perception of voice quality changes caused by varying vocal fold stiffness, Acta Acustica united with Acustica, 102(2), 209-213. [pdf] [link]
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