Intraglottal pressure profiles for a symmetric and oblique glottis with a divergence angle of 10 degrees

Human phonation does not always involve symmetric motions of the two vocal folds. Asymmetric motions can create slanted or oblique glottal angles. Thi s study reports intraglottal pressure profiles for a Plexiglas model of the larynx with a glottis having a 10-degree divergence angle and either a sym metric orientation or an oblique angle of 15 degrees. For the oblique glott is, one side was divergent and the other convergent. The vocal fold surface s had 14 pressure taps. The minimal glottal diameter was held constant at 0 .04 cm. Results indicated that for either the symmetric or oblique case, th e pressure profiles were different on the two sides of the glottis except f or the symmetric geometry for a transglottal pressure of 3 cm H2O. For the symmetric case, flow separation created lower pressures on the side where t he flow stayed attached to the wall, and the largest pressure differences b etween the two sides of the channel were 5%-6% of the transglottal pressure . For the oblique case, pressures were lower on the divergent glottal side near the glottal entry and exit, and the cross-channel pressures at the glo ttis entrance differed by 27% of the transglottal pressure. The empirical p ressure distributions were supported by computational results. The observed aerodynamic asymmetries could be a factor contributing to normal jitter va lues and differences in vocal fold phasing. (C) 2001 Acoustical Society of America.