Dolphin target detection processes investigation using finite element model

Abstract

Dolphins and porpoises use their sophisticated biosonar systems for targets detection, within a range of a few meters to about 200 m, there is not a better sonar on the planet. In this study, the high resolution computer tomography (CT) scan data were used to create the detecting click signal propagation models of Atlantic bottlenose dolphins (Tursiops truncatus) and harbor porpoise (Phocoena phocoena). The finite element methods (FEM) were used to simulate the processes of the clicks emitted from phonic lips and transmit to the water through animals’ heads. The biosonar beam forming in the nearfield and farfield including the amplitude contours were determined and compared to the prior measurement results. There were no evidences of convergence in the farfield, which were consistent with measurement results for Tursiops truncatus. Additionally, in a cross-modal matching experiments with Tursiops, we found that the accuracy of the successive match was significantly different when the following subjects with same shape were used (water-filled PVC pipes, air-filled PVC pipes, foam ball array, and PVC pipes wrapped by foam) the results of FE model shed some light on the reasons why the animal has significant difference in performances when detecting different targets in the experiments.