310 A Study of Vocal Fold Vibrations by Means of Simultaneous Measurement of Subglottal Pressure and Flow Velocity Variations Just Above the Glottis

Human voices are originated by vibration of vocal folds in 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 vocal fold vibration is believed to be important to elucidate mechanism of human phonation. Thus, in the present study, experimental analysis of this vibration was made to clarify phonation mechanism and seek better modeling of vocal folds, focusing on direct measurement of subglottal pressure and glottal velocity and simultaneous observation of vocal fold movement by means of a high-speed digital camera. The experimental results prove that subglottal pressure increases in closing phase of vocal folds and decreases in opening phase and high speed airflow just above glottis results in closing of vocal folds. This fact is important since it gives a crucial hint for better simulation model of phonation mechanism.