Self-Excitation Vocalization Analyses of Vocal Chord Under Breathing Flow and Wide Frequency Change by Muscle Activation

This paper presents some analyses and experiments on vocalizing mechanics in vocal chord due to the breathing flow, and their wide range of frequency change by varing the interior muscle activations. Three dimensional dynamic response of the hyperelastic and finite deformation body of the vocal chord and the interior muscles have been analysed at first and the exclusive FEM system has been developed. The eigen frequencies and vibration characteristics of the vocal chord are analysed by varing the activation level of the interior muscles. The Helmholtz equation of the breathing flow under transient state has been analysed to obtain the pressure pulsation characteristics behind the vocal chord during vocalizing of the source voice. Combining both approaches stated aboves, the mechanics of the self-exciting vibration of the vocal chord have been studied in detail using the root-locus approach. It is also found in the analysis and experiments that the frequency of the self-exciting vibration can be widely varied with the activation level of the interior muscle of the vocal chord, giving rise to a variety of frequency level of the source voice.