Abstract:

Vocal-fold oscillation has been investigated from the viewpoint of kinematics and dynamics of single glottal pulse at normal intensity vocal fry frequencies, using a modified Sondhi tube. Key moments in the cycle are opening and closing actions, which appear to be very sudden. These events may be noted in two ``kinks'' which appear along traces of the EGG and glottal cross-sectional area functions. Between opening and closing boundary encounters, vocal folds seem to travel in quasiballistic fashion, being slingshotted out by feedback from the subglottal pressure wave and ending their traverse across the glottal opening with mutual collision The abrupt opening and closing gestures of the glottis permit the glottal valve to modulate subglottal volume flow against the inertia of tracheal air. Acoustic emissions from the glottis may be thought of as flow fluctuations which compensate for changes in fluctuating glottal area, thereby maintaining approximately incompressible flow. Fluctuations of glottal area generate the bulk of F0 energy while upper formants owe their spectral energy to boundary layer events that happen near the violent endpoints of glottal motion.