David A. Berry
Ingo R. Titze
Brad H. Story
Dept. of Speech Path. and Audiol., Natl. Ctr. for Voice and Speech, Univ. of Iowa, Iowa City, IA 52242
Hanspeter Herzel
Technical Univ. Berlin, Hardenbergstr. 36, D-10623 Berlin, Germany
Bifurcation analysis is applied to vocal fold vibration in excised larynx experiments. In particular, two-dimensional bifurcation diagrams are generated in a parameter plane spanned by subglottal pressure and asymmetry of vocal fold adduction or elongation. Various phonatory regimes are observed, including single vocal fold oscillations. Selected spectra demonstrate a correspondence between the observed phonatory regimes and vocal registers noted in the literature. Many instabilities or bifurcations are noted in the regions of coexistence, i.e., the regions where the phonatory regimes overlap. Bifurcations are illustrated with spectrograms and fundamental frequency contours. Where possible, results from these studies are related to clinical observations. [This research was supported by Grant No. P60 DC00976 from the National Institute on Deafness and Other Communication Disorders.]