Finite Element Modeling of Effects of Acoustic Stimulation on Fish Otoliths

Early work has shown that exposure to high-intensity sounds can damage the sensory epithelia of fish ears and impair their hearing. However, experiments suggest that when the acoustic stimulus impinges on the ears from different directions, the damage level varies significantly. Therefore, it was hypothesized that the angle of the incident sound might play a part in the propensity to cause damage. To test the hypothesis and gain insight into the differential movement of the otolith relative to the epithelia, finite element models based on microCT data of the saccular otolith of a bight redfish (Centroberyx gerrardi) was built, which modeled the otolith motion to acoustic stimulations from the horizontal and vertical directions. Sound pressure level, relative displacement, acceleration, and shear stress at the surfaces of the otolith and macula (water-otolith boundary) were compared. The results suggest that the incident angle of the sound and the geometry of the sulcal groove play an important role in causing different damage levels to the fish ears.