FURTHER-STUDIES OF PHONATION THRESHOLD PRESSURE IN A PHYSICAL MODEL OF THE VOCAL FOLD MUCOSA

This paper reports results of further experimentation on a previously developed physical model of the vocal-fold mucosa [Titze et al., J. Ac oust. Sec. Am. 97, 3080-3084 (1995)]. The effects of vocal-fold thickn ess, epithelial membrane thickness, and prephonatory glottal geometry on phonation threshold pressure were studied. Phonation threshold pres sures in the range of 0.13 to 0.34 kPa were observed for an Il-mm-thic k vocal fold with a 70-mu m-thick ''epithelial'' membrane for differen t ''mucosal'' fluid viscosities. Higher threshold pressure was always obtained for thinner vocal folds and thicker membranes. In another set of experiments, lowest offset threshold pressure was obtained for a r ectangular or a near-rectangular prephonatory glottis (with a glottal convergence angle within about +/- 3 degrees). It ranged from 0.07 to 0.23 kPa fur different glottal half-widths between 2.0 and 6.0 mm. The threshold for more convergent or divergent glottal geometries was con sistently higher. This finding only partially agrees with previous ana lytical work which predicts a lowest threshold for a divergent glottis , The discrepancy between theory and data is likely to be associated w ith Bow separation from a divergent glottis. (C) 1997 Acoustical Socie ty of America.