ASA 125th Meeting Ottawa 1993 May

4aAB3. Transmission beam pattern of a false killer whale.

Whitlow W. L. Au

Jeffrey L. Pawloski

Ted W. Cranford

Robert C. Gisner

Paul E. Nachtigall

Naval Command Control and Surveillance Ctr., P.O. Box 997, Kailua, HI 96734

The echolocation transmission beam pattern of a false killer whale (Pseudorca crassidens) was measured in the vertical and horizontal planes. A vertical array of seven broadband miniature hydrophones was used to measure the beam pattern in the vertical plane and a horizontal array of the same hydrophones was used in the horizontal plane. The measurements were performed in the open waters of Kaneohe Bay, Oahu, Hawaii, with the whale performing a discrimination task. The width of the beams in both planes were similar to those of the Atlantic bottlenose dolphin (Tursiops truncatus), and broader than those of the beluga whale (Delphinapterus leucas). The major axis of the vertical beam was directed slightly downwards between 0(degrees) and -5(degrees), in contrast to the +5 to 10(degrees) for Tursiops and Delphinapterus. The beam in the horizontal plane was directed forward. Differences in the fatty structure of the melon of Pseudorca, Tursiops, and Delphinapterus could explain differences in the elevation angle of the vertical beam axis. [sup a)]At SAIC, Kailua, HI 96734.