Beaked and Baleen Whale Hearing: Modeling Responses to Underwater Noise

Abstract : Ultimately this research is to provide proof of concept for using modeling techniques to provide reliable hearing estimates for species thought to be most liable to impacts from oceanic sound sources. To address this, preliminary data were acquired that may later be applied toward calculating a model audiogram of large whale hearing that demonstrates the ability to accurately estimate hearing ranges and peak sensitivities using current anatomical and biomedical engineering techniques. The model proposed is to be created from neuroanatomical data combined with direct measures of middle and inner ear stiffness. For now, preliminary data have been collected, with anatomical measures obtained for the heads and inner ears of two beaked and two minke whales, as well as for 10 ears from these and additional animals. A partial frequency range map for the minke has been completed via CT and histologic data. Specimens have been used to redesign a piezo electric system to accommodate baleen ears, and point stiffness measures have been accomplished for the middle ears of some of the test minke specimens. These data have been compared with earlier results from multiple odontocete and land mammal ears.