The effect of exit radii on intraglottal pressure distributions in the convergent glottis

Phonation depends upon the dynamic distribution of glottal air pressures that act upon the vocal folds, as well as tissue properties of the vocal folds. The glottal wall pressures depend upon the shape, size, and diameter of the glottis for a given flow. This study examined how the radius of curvature of the glottal exit in the converging glottis affects the wall pressures in the glottis. The following exit radii were used: 0.0908 cm, 0.0454 cm, and 0.0050 cm for the 10° case, and 0.0841 cm, 0.021 025 cm, and 0.0050 cm for the 20° case. Minimal glottal diameter and flow were held constant at 0.02 cm and 73.2 cm³/s, respectively. The computational fluid dynamics code FLUENT was used to obtain the pressure profiles. Both the transglottal and intraglottal pressures increased as the exit radius decreased, resulting in an increase in flow resistance and an increase in the outward pressure forces on the vocal folds. The results suggest that the glottal exit curvature should be well specified when building computational or physical models of the vocal folds.