The influence of flow model simplification on phonation onset.

Abstract

In previous studies, phonation onset characteristics were investigated using linear stability analysis in a continuum vocal fold model. Although this approach allowed efficient calculation of phonation onset, a one‐dimensional simplified glottal flow model was used in these previous studies, and it is unclear how phonation onset prediction was affected by this flow model simplification. In this study, to understand the effects of glottal flow simplification on phonation, phonation threshold pressure and onset frequency as a function of vocal fold geometry and stiffness were calculated using a two‐dimensional continuum vocal fold model coupled with two‐dimensional incompressible Navier–Stokes flow equations. These phonation threshold pressures and onset frequencies were compared to those predicted from a linear stability analysis of the same vocal fold model coupled with a one‐dimensional glottal flow model, as in previous studies. The results show that phonation threshold pressures and onset frequencies predicted from these two approaches compared well for large glottal gaps. The difference increased as the glottal gap was constricted. Hence, the results suggest that beyond a certain glottal gap, viscous effects (except flow separation) are negligible and phonation characteristics can be predicted using a simplified and thus computationally efficient glottal flow model. [Work supported by NIH.]