Analysis of Human Vocal Fold Vibrations by Means of Measurement of Flow Velocity Variations Just Above the Glottis and Simultaneous Observation of Vocal Fold Movement Using High-Speed Digital Camera

Abstract

Human voices are originated by vibration of vocal folds in the larynx. This vibration is induced by the airflow that is expelled through glottis, and causes a series of the pulses of the airflow. These pulses excite vocal tract and bring about the passive resonance of the vocal tract in all voiced sounds. Therefore, detailed study of this airflow is believed to be important to elucidate mechanism of human phonation. Thus in the present study experimental analysis of this airflow just above glottis was made to clarify phonation mechanism and seek better modeling of vocal folds, focusing on direct measurement of airflow velocity by means of a tiny hot-wire probe and simultaneous observation of vocal fold movement by means of a high-speed digital camera. The experimental results show that the periodic change of the airflow velocity occurs out of the phase of opening of glottis, though both have the same fundamental frequency. This fact is important since it gives a crucial hint for better simulation model of phonation mechanism.