Interrelationships between intranarial pressure and biosonar clicks in bottlenose dolphins (Tursiops truncatus)

Abstract

Recent advances in technology permitted the first simultaneous digital recording of intranarial pressure and on-axis acoustic data from bottlenose dolphins during a biosonar target recognition task. Analysis of pressurization events in the intranarial space quantifies and supports earlier work, confirming that intranarial pressure is increased when whistle vocalizations are emitted. The results show complex relationships between various properties of the biosonar click to the intranarial pressure difference at the time it was generated. The intranarial pressure that drives the production of clicks is not the primary determinant of many of the acoustic properties of those clicks. A simple piston-cylinder physical model coupled with a sound production model of clicks produced at the monkey-lips/dorsal bursae complex yields an estimate of mechanical work for individual pressurization events. Individual pressurization events are typically associated with a single click train. Mechanical work for an average pressurization event is estimated at 10 Joules.