Influence of the flow field structure formed downstream of the human vocal cord model on the sound generated

Abstract

Loss of oral communication after total laryngectomy reduces the quality of life of the patient. Understanding the basic sound generation mechanisms in the larynx is necessary for the development of voice reconstruction. In this study, a model simulates the self-excited vibrations of the vocal cords in the larynx was constructed. Experimental measurements were performed on the model to identify the main factors and mechanisms of the sound generated by the model. The flow field downstream of the model was measured using PIV. Then, the sound pressure was estimated by applying the Ffowcs Williams-Hawking equation to the measured flow field. The estimated sound pressure was in good agreement with the actual sound pressure measured by the microphone. The main source of the generated sound was found to be the direct sound from an aerodynamic source in the downstream flow field of the model. The vortex structures in the vicinity of the slit are mainly related to this sound generation. As the slit opens and closes, the pressure near the slit fluctuates over time, and generates sound waves. This is related to the vortex structure identified by the Q-criterion occurring in the same region.

Keywords

• aeroacoustics
• particle image velocimetry
• tomographic piv
• larynx
• vocal cords
• self-excited vibration
• unsteady flow
• vortex