Effect of vocal fold radii on pressure distributions in the glottis

Abstract

Modeling laryngeal aerodynamics requires specification of glottal geometry. This study examines primary effects of glottal inlet and outlet radii. A velocity-pressure integrated finite-element method produced glottal pressure profiles for three radius conditions: completely rounded vocal folds (the edematous condition}; vocal folds with sharp corners; and vocal folds with realistic radii. Converging, uniform, and diverging glottal shapes were used with a Reynolds number of 800 and a minimum glottal diameter of 0.02 cm. For the diverging glottis, sharp corners produce unrealistically large local negative pressure spikes due to convective acceleration. For convergence, the expansion curvature of realistic radii creates pressure recovery hear the glottal exit, producing a location of negative pressure. This may reinforce the motion phase difference between the upper and lower glottal regions due to a net positive pressure upstream and a net negative pressure downstream. For the completely rounded vocal fold, both positive and negative pressures appear upstream in the glottis, with a potential tendency to inhibit vocal fold motion. [Work supported by NIH R01 DC00157 to The University of Iowa.]