Narrow-Band Sonar Signals of Small Cetaceans

The sonar signals of some of the smallest cetaceans are very similar to each other and very different than that of mid-sized cetaceans. Signals of Cephalorhynchus hectori, Cephalorhynchus commersonii (genus Cephalorhynchus), Phocoena phocoena, Neophocoena phocoena and Phocoenoides dalli (family phoc...

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Bibliographic Details
Main Author: Au, Whitlow W.
Other Authors: NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
Format: Text
Language:English
Published: 1991
Subjects:
Biology
*MARINE BIOLOGY
*SONAR SIGNALS
RESOLUTION
PULSES
SIGNALS
PRESSURE
BAYS
ANIMALS
BANDWIDTH
SONAR
HAWAII
ENERGY
ACOUSTICS
CETACEANS
REPRINTS
PE62435N
WUDN688674
Delphinapterus leucas
Phocoena phocoena
Online Access:http://www.dtic.mil/docs/citations/ADA248359
http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA248359
Description
Summary:The sonar signals of some of the smallest cetaceans are very similar to each other and very different than that of mid-sized cetaceans. Signals of Cephalorhynchus hectori, Cephalorhynchus commersonii (genus Cephalorhynchus), Phocoena phocoena, Neophocoena phocoena and Phocoenoides dalli (family phocoenidae) are compared with those of some larger dolphins. Signals of Tursiops truncatus, Delphinapterus leucas and Pseudorca crassidens, housed in Kaneohe Bay, Oahu, Hawaii, have peak frequencies between 100-200 kHz, with high amplitudes (210-225 dB re 1 microPa), short durations (50-70 micro s), and wide bandwidths (30-40 kHz). Some of the smaller cetaceans emit signals having peak frequencies between 120 and 140 kHz, with low amplitudes (< 170 dB re 1 microPa) , long durations (170-430 micro s) and narrow bandwidths (7-11 kHz). Double pulses are also emitted regularly by some of the smaller dolphins and very infrequently by the larger dolphins. Signals used by the smaller animals may reflect constraints associated with their small size and differences in generation mechanisms. For a given peak acoustic pressure, there is 3 to 4 times more energy in the signals of the smaller cetaceans. However, because of the narrower bandwidths, the distance resolution capability of the small cetacean signals is between 2 to 3.5 times inferior to that of the larger animals. Furthermore, the narrow bandwidth signals do not possess any doppler resolution properties. Marine biosystems, Marine biology. Published in the program of the Biennial Conference on the Biology of Marine Mammals (9th), held in Chicago, IL on 5-9 December 1991.

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