Abstract:

The penetration of dolphin sonar clicks into the ocean sediment is modeled using Biot's theory of sound propagation in porous media. A range of sediment types are considered, from soft mud to sand. The expected signal loss as a function of depth and grazing angle are computed. At any given value of loss, the penetration may vary by more than an order of magnitude depending on sediment type. The penetration is modified by critical angle effects and interference between different sediment acoustic waves. In modeling the acoustic scattering from buried objects, it is not sufficient to compute the net acoustic pressure, but also the pressures of each contributing sediment acoustic wave component. [Work supported by ONR code 342.]