Intraglottal velocity and displacement measurements in an excised larynx
Liran Oren, Ephraim J. Gutmark, Sid M. Khosla · The Journal of the Acoustical Society of America · 2012
A major assumption of previously published PIV measurements in excised larynges, is that the vortices seen directly above the glottal exit during closing are due to the flow separation vortices (FSV) that formed in the glottis. This assumption needed experimental validation. In addition, the pressures associated with the vortices above the vocal folds may be different than the pressures generated by the intraglottal FSV. Previous studies also relied on images of the glottal opening taken from above of the folds to evaluate the displacement of the folds. This method cannot separate the dynamic of the folds that occurs along their superior and inferior edges. The current study uses a major modification of the PIV techniques previously described to simultaneously measure intraglottal velocity fields and intraglottal geometry. The intraglottal pressure distribution is computed from the velocity measurements by solving the pressure Poisson equation. The results show that strong negative pressure is formed towards the superior edge of the folds. This negative pressure can produce additional force during closing. The displacement of the folds, during closing, is also extracted from the PIV images and it shows that the acceleration of the superior edge is consistently higher than the inferior edge.