In this collaborative research with San Diego State University’s Department of Biology and with Scripps Institution of Oceanography, a finite element vibroacoustic toolkit was applied to the sound transmission in the head of a beaked whale. The model is based on CT data sets as well as physical measurements of sound-propagation characteristics of actual tissue samples. FEM results concern pathways by which sounds reach the ears.
Simulations are revealing a previously undescribed ‘gular pathway’ for sound reception in this species. Propagated sound pressure waves enter the head from below and between the lower jaws, pass through an opening created by the absence of the medial bony wall of the posterior mandibles, and continue toward the bony ear complexes through the internal mandibular fat bodies. This new pathway has implications for understanding the evolution of underwater hearing in beaked whales; this model also provides evidence for receive beam directionality, off-axis acoustic shadowing and a plausible mechanism for the long-standing orthodox sound reception pathway.