Modeling Otoacoustic Emission Group Delays in the Lizard Auditory Periphery
Otoacoustic emissions (OAEs) are sounds generated and subsequently emitted by a healthy ear (detectable using a sensitive microphone) which appear in a wide range of vertebrate species. While the exact generation mechanisms remain unclear, OAEs evoked using an external stimulus exhibit significant group delays across a wide frequency range, on the order of 1-2 ms or greater. In mammals such as humans, these delays are generally thought to arise due to the presence of cochlear traveling waves. However, in classes such as lizards, such waves are noticeably absent. The present study hypothesizes that these delays are in fact associated with the sharp tuning manifested in the auditory periphery and represent the build-up time of highly tuned coupled oscillators. Preliminary model results for the gecko ear show remarkable agreement with empirical data and predict that emission group delays increase with increasing sharpness of tuning (as typically measured via auditory nerve fiber responses).

