Auditory Localization of Ground-Borne Vibrations in Snakes

Abstract

Interaural time differences allow many animals to perform azimuthal sound localization. Snakes lack a tympanic membrane, external ear openings, and any other superficial indication of an auditory mechanism. They do, however, possess an inner ear with functional cochlea. The oval window is connected through a loss-free osseous lever system to the two, de facto independent, sides of the lower jaw, which typically rest on the substrate. The footfall of prey generates small-amplitude, low propagation velocity, Rayleigh waves in the soil. This type of wave can be described as fluid motion. Accordingly we apply naval-engineering techniques to show that lower-jaw motion gives rise to a neuronal representation of the auditory world with realistic sensitivity and stereo precision.