A theoretical description of the tree cricket ear as a highly phase sensitive biomechanical interferometer.

Sound localization is essential for insect survival, enabling them to pinpoint predators and conspecifics. However, their minute size hinders the use of inter-aural time or intensity differences, a strategy employed by mammals for localizing sound. In this study, we numerically demonstrate that tree cricket hearing systems can act as an interferometer to support sound localization by first splitting the sound wave into two parts, sending one wave to an anterior tympanic membrane and sending the second to a posterior tympanic membrane. The membranes then carry the split waves to a common point, the tracheal wall, where the re-assembly of the wave causes mechanical interference that is sensitive to microsecond time delays. This principle, interferometry, is usually thought of in terms of light and can measure extremely small time delays. Tree cricket ears are equipped to use the same principle as the light interferometer, except with sound, to measure extremely precise locations.