The Physics of the Human Vocal Folds as a Biological Oscillator

Abstract

The human voice results from the vibration of air at the vocal folds (VF), which behave as a damped oscillator controlled by intraglottic pressure and tranglottic airflow. This chapter presents a complete synthesis of the physics of vocal dynamics (1) during a sustained oscillation, particularly with regard to the phase relationship between intraglottic pressure and glottal opening and closing; (2) during the onset of the oscillation, particularly with regard to the mechanism explaining the triggering of the initiation of the oscillation; and (3) during the decay of the damped oscillations during voice offset, particularly with regard to the effect of lung volume. The importance of air volume as an essential component of the vibratory system is highlighted. The experimental data are obtained in vivo by simultaneous measurement of the transglottic flow and the glottic surface, which allows the calculation of the intraglottic pressure and its interaction with the inertia of the vocal tract.