A new model for the source of vowels based on the vortex sound

Abstract

This paper presents a new model for the source of vowels based on the vortex soundgenerated at the glottis by an interaction between the kinetic vibration of the glottal muscle and the airflow through it. This new model distinguishes itself from previous models in presenting analytical (mathematical) expression of the waveform generated at the glottis, because all of the previous models regard the vocal tract as the primary source for determining the waveform of the sound, whereby simply assuming some arbitrary waveform of the sound at the glottis. Our new model states that the airflow through the glottis generates vortices, whichsubsequently generates acoustic sound, as Lighthill's general theory of aerodynamic sound has stated and that, in some cases, the acoustic sound causes a significant change in the airflow pressure affecting, in turn, the glottal movement. Based on the model presented here, some vowels have actually been synthesized by computer programs written in C which generate WAV-format files on MS Windows. Furthermore, using the new model, reasonable explanations are provided for boththe issue of duty ratio of the glottis' opening and closing movement and the nonlinear nature of the vocal phenomenon, in particular the mechanism of the falsetto.