Sound generation by unsteady flow ejecting from the vibrating glottis based on a distributed parameter model of the vocal cords

The purpose of the present paper is to clarify the effects of unsteady glottal flow on phonation. We perform numerical experiments with respect to vocal cord vibrations in order to verify the validity of the proposed model for a glottal sound source. In addition, the prediction of pressure waves induced by unsteady glottal jets is attempted. Good agreement between the numerical results and the measured data of the properties of the glottal source indicates that the proposed model is a good tool for the analysis of speech production. Simulated pulsatile glottal jets show the generation of high-frequency noises in a pressure wave at the glottis and the unsteady and asymmetric motion of vortices. These vortices cause amplitude fluctuations in the pressure wave downstream near the glottis, although pressure waves far from the glottis are not greatly affected. In conclusion, the unsteady glottal flow affects only the area near the glottis and does not greatly affect speech waves radiating from the mouth.