Voice production model employing an interactive boundary-layer analysis of glottal flow

A voice production model has been studied by considering essential aerodynamic and acoustic phenomena in human phonation. Acoustic voice sources are produced by the temporal change of volume flow passing through the glottis. A precise flow analysis is therefore performed based on the boundarylayer approximation and the viscous-inviscid interaction between the boundary layer and core flow. This flow analysis can supply information on the separation point of the glottal flow and the thickness of the boundary layer, which strongly depend on the glottal configuration, and yield an effective prediction of the flow behavior. When the flow analysis is combined with a mechanical model of the vocal fold, the resulting acoustic wave travels through the vocal tract and a pressure change develops in the vicinity of the glottis. This change can affect the glottal flow and the motion of the vocal folds, causing source-filter interaction. Preliminary simulations were conducted by changing the relationship between the fundamental and formant frequencies and their results were reported.