Acoustic Propagation Investigation of a Dolphin Echolocation Pulse at Water-Sediment Interface Using Finite Element Model

Dolphins use their sophisticated biosonar to achieve complex underwater detection tasks, and it has been proved that dolphin can prey small fish, hidden in the sediment, by using dolphin echolocation pulses. Dolphin echolocation pulses (click) is a kind of broadband and short acoustic signal, produced by echolocation dolphins when they detect, recognize and classify target. In this study, the acoustic transmission performance of a dolphin click was evaluated by using Finite element method. Using Biot's theory, the sandy sediment was built in poroelasticity material. The water-sediment boundary was established by the module of multi-physics coupling. The reflection and refraction coefficients of dolphin click were calculated by Fourier synthesis method. Based on refraction coefficient, the critical angle was estimated. The results of finite element model shed some light on the reasons why the dolphin can prey the small fish hidden in sediment, and it also shows a promising way to design a bio-inspired sonar for buried target detection.