Sound localization of fish calls recorded by two stereo-underwater-recorders

Abstract

Some fish produce sounds during the spawning and ramping behaviors. These sounds have been used for discrimination of fish species. Recently, the method was proposed to estimate the direction of fish call by using the arrival time difference between two hydrophones. However, it was difficult to estimate sound localization in the case of using the measured data from two hydrophones, that is, one stereo recorder. In this presentation, we used two stereo recorders, including four hydrophones for sound localization. The sound data were measured during spawning at fish, Hexagrammos otakii, in the littoral region of Usujiri-cho, Hakodate, Hokkaido, Japan (N41°56'11", E140°56'41"). First, the fish calls were automatically detected by using the sound features including duration, max frequency, and amplitude. These features were determined by analyzing the sound data manually. Second, the arrival directions of detected fish calls were estimated in terms of each stereo recorder. Then, the fish calls were localized by using two arrival directions. As a result, it was clear that there were fishes producing call sounds around the spawning bed.