Analysis of recent experimental studies of phonation threshold pressure done with a physical model of the vocal fold mucosa.
Lewis P. Fulcher, Ronald Callaway Scherer, Chen Liu, Marco Nardone · The Journal of the Acoustical Society of America · 2009
The pioneering work on the physics of small amplitude oscillations of the vocal folds by Titze resulted in a simple analytic formula that predicted the phonation threshold pressure of the uniform glottis to be a linear function of the glottal half-width, to be directly proportional to energy dissipation properties of the vocal fold, and to be reduced by the presence of a vocal tract. These relationships have been examined in a series of experiments [R. Chan and I. Titze, “Dependence of phonation threshold pressure on vocal tract acoustics and vocal fold tissue mechanics,” J. Acoust. Soc. Am. 119, 2351–2362 (2006)], and the linear connection with glottal half-width has been observed in several cases. However, the analysis described above did not consider the role of viscosity of the air, which may be important at small widths, as suggested by Lucero. The present study examines these experiments in the context of the surface wave model developed by Titze using intraglottal pressure distributions taken with the static physical model of the glottis M5. The M5 data include effects of viscosity and of flow separation. Preliminary results indicate that the threshold pressure should decrease as glottal width decreases, over the entire range of glottal widths examined by Chan and Titze. [Work supported by NIH R01DC03577.]