Flow-Structure-Acoustic Interaction in a Prestressed Human Larynx Model

Abstract

For investigating the fluid-structureacoustic coupled (FSA) process of human phonation, synthetic models of the vocal folds (VF) were designed which showed flow-induced oscillations and the sound production process. The models were developed to analyse the flow-induced vibration depending on the prestress similar to human vocal folds. They consisted of a silicon rubber whose Young’s moduli corresponds to those found in human vocal folds between 3 and 13.2 kPa.

The major aim of this work was to to observe the whole FSA process and to determine the acoustic sources. Therefore two approaches were applied: Firstly the vibration of the VFs was recorded using a high-speed camera triggered by the subglottal pressure to determine the phase shift between the two signals. Secondly synchronous measurements of the subglottal pressure, the flow velocity behind the VFs and the acoustic pressure were performed. In all investigations the influence of tension and stiffness of the VFs were analysed.

The results shows that the vibration frequency and the phase shift between the subglottal pressure and the glottal width depended on different boundary conditions. The synchronous measurements determined the pressure fluctuations of the pulsating flow rate as main acoustic source.