Fluid-structure-interaction and aero-acoustic simulations of vocal membrane vibration in the larynx of echolocating bats*

Echolocating bats, despite their millimeter-size mammalian larynges, can produce ultrasound emissions with very high frequency and intensity. Bat larynges have a bilateral tissue structure called vocal membranes which are unique among mammals. Previous studies have argued that this structure might be responsible for the ultrasound generation and closely related to the ability of bats to precisely modulate the frequency of emitted signals. In the current study, a canonical bat larynx computational model is developed based on high-resolution micro-CT scans of a bat larynx. Fluid-structure-interaction simulations are carried out to study the effects of the vocal membranes on the flow field. Results of the energy extraction from the flow to the vocal membranes will be presented and the influence of the vibrating frequency and amplitude on the acoustic signals will be discussed. Implications of the vocal membrane vibration for the acoustic signal emission will also be examined.