Bifurcation analysis was applied to vocal fold vibration in excised la
rynx experiments. Phonation onset and vocal instabilities were studied
in a parameter plane spanned by subglottal pressure and asymmetry of
either vocal fold adduction or elongation. Various phonatory regimes w
ere observed, including single vocal fold oscillations. Selected spect
ra demonstrated correspondence between these regimes and vocal registe
rs noted in the literature. To illustrate the regions spanned by the v
arious phonatory regimes, two-dimensional bifurcation diagrams were ge
nerated. Many instabilities or bifurcations were noted in the regions
of coexistence, i.e., regions in which the phonatory regimes overlap.
Bifurcations were illustrated with spectrograms and fundamental freque
ncy contours. Where possible, results from these studies were related
to clinical observations.