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Phonation onset: vocal fold modeling and high-speed glottography
P Mergell1, H Herzel, T Wittenberg
1Department of Phoniatrics and Pedaudiology, University Erlangen-Nuremberg, Germany. mergell@phoni.med.uni-erlangen.de
The Journal of the Acoustical Society of America
|July 22, 1998
Summary
Phonation onset, the start of vocal fold vibration, can be modeled as a Hopf bifurcation. A new parameter, phonation onset time, quantifies this transition for clinical diagnosis.
Area of Science:
- Voice Science
- Biophysics
- Speech Pathology
Background:
- Phonation onset involves the transition from damped to sustained vocal fold oscillations.
- This transition is influenced by laryngeal parameters like adduction and subglottal pressure.
- Understanding phonation onset is crucial for diagnosing voice disorders.
Purpose of the Study:
- To model phonation onset using dynamical systems theory, specifically a Hopf bifurcation.
- To derive an analytic envelope curve for oscillation onset.
- To identify a physiological parameter, phonation onset time, for quantitative assessment.
Main Methods:
- Mathematical modeling of vocal folds to analyze the Hopf bifurcation.
- Deduction of an analytic envelope curve governed by a single time constant.
- Extraction of phonation onset time from simulated data (two-mass model) and high-speed video recordings.
Main Results:
- The oscillation onset is characterized by a single time constant, identified as phonation onset time.
- Phonation onset time reflects the laryngeal state prior to phonation.
- Experimental measurements showed good agreement with theoretical predictions.
Conclusions:
- Phonation onset time serves as a quantitative criterion for clinical diagnosis of voice function.
- The Hopf bifurcation framework provides a robust model for understanding phonation onset.
- This parameter aids in assessing and classifying phonation onset in clinical settings.