Middle Ear Mechanics in the Barn Owl

Abstract

The barn owl is a common research subject in auditory science due to its exceptional capacity for high frequency hearing and superb sound source localization capabilities. Despite longstanding interest in the auditory performance of barn owls, the function of its middle ear has attracted remarkably little attention. Here, we report the middle ear transfer function measured by laser Doppler vibrometry and direct measurements of inner ear pressures. Our results illustrate that the barn owl middle ear produces a pressure gain between the ear canal and the inner ear vestibule of up to 35 dB, which is comparable to that seen in mammals. The footplate velocity transfer function magnitudes overlap with those measured in other bird species, however the differences in phase between the footplate velocity and the sound pressure stimulus indicate a middle ear group delay that is notably shorter than other birds. This work brings us closer to a more complete understanding of the physiology of hearing in a model organism in auditory science.