Localization of dolphin whistles through frequency domain beamforming using a narrow aperture audio/video array

Abstract

Correlating the acoustic and physical behavior of marine mammals is an ongoing challenge for scientists studying the links between acoustic communication and social behavior of these animals. This talk describes a system to record and correlate the physical and acoustical behavior of dolphins. A sparse, short baseline audio/video array consisting of 16 hydrophones and an underwater camera was constructed in a cross configuration to measure the acoustic signals of vocalizing dolphins. The bearings of vocalizing dolphins were estimated using the broadband frequency domain beamforming algorithm for sparse arrays to suppress grating lobes of Thode et al. [J. Acoust. Soc. Am. 107 (2000)]. The estimated bearings from the acoustic signals were then converted to video image coordinates and a marker was placed on the video image. The system was calibrated both at an indoor tank and from an outdoor dock at UMass Dartmouth prior to field tests in a natural lagoon at the Dolphin Connection on Duck Key, FL. These tests confirmed that the system worked well within the limits of underwater visibility by consistently placing the marker on or near the whistling or echolocating dolphin. [Work supported by NSF Ocean Sciences.]