Phonation onset: Vocal fold modeling and high-speed glottography

Abstract

Phonation onset is discussed in the framework of dynamical systems as a Hopf bifurcation, i.e., as a transition from damped to sustained vocal fold oscillations due to changes of parameters defining the underlying laryngeal configuration (e.g., adduction, subglottal pressure, muscular activity). An analytic envelope curve of the oscillation onset is deduced by analyzing the Hopf bifurcation in mathematical models of the vocal folds. It is governed by a single time constant which can be identified with the physiological parameter phonation onset time. This parameter reflects the laryngeal state prior to phonation and can be used as a quantitative classification criterion in order to assess the phonation onset in clinical diagnosis. The extraction of the phonation onset time from simulated time series using a simplified two-mass model and from digital high-speed videos is described in detail. It shows a good agreement between theory and measurement.

Vocal fold vibration measurements using laser Doppler vibrometry

“…The measured times were in the expected range of times as indicated in the literature. 24 This study reports direct velocity measurements of the in vivo human vocal fold superior surface. Previous studies have required the use of image processing and analysis to indirectly measure the velocity and displacement.…”

A Comparison of Sung and Spoken Phonation Onset Gestures Using High-Speed Digital Imaging

“…Previous studies 23,24 have organized the timing of phonation onset events in terms of vocal fold adductory positioning and initiation of vocal fold vibrations. These vibrations may begin from small-amplitude medial excursions to oscillations which increase in amplitude until they reach maximum amplitude and a steady state of vibration.…”

Messung und Interpretation von irregul�ren Stimmlippenschwingungen

“…6). In einer Modellrechnung ist es gelungen,den Einschwingvorgang der Stimmlippen durch nur einen Parameter zu beschreiben [16].Erfahrungen mit anderen Untersuchungsparadigmen liegen bisher nur in geringem Umfang vor. …”