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The 20-Hz Signals Of Finback Whales (Balaenoptera Physalus), William Watkins, Peter Tyack, Karen Moore, James Bird
The 20-Hz Signals Of Finback Whales (Balaenoptera Physalus), William Watkins, Peter Tyack, Karen Moore, James Bird
James E Bird
The 20-Hz signals of finback whales (Balaenoptera physalus) were analyzed from more than 25 years of recordings at a variety of geographic locations on near-surface hydrophones close to whales and on deep hydrophone systems. These signals were composed of 1-s pulses of sinusoidal waveform with downward sweeping frequency from approximately 23 to 18 Hz at variable source levels up to 186 dB (re: 1 microPa at 1 m), usually with slightly lower levels for the pulses at the beginning and end of sequences. These "20-Hz" pulses were produced in signal bouts (separated by more than 2 h) lasting as long …