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The influence of signal parameters on the sound source localization ability of a harbor porpoise (Phocoena phocoena)

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Author: Kastelein, R.A. · Haan, D.de · Verboom, W.C.
Type:article
Date:2007
Institution: TNO Defensie en Veiligheid
Source:Journal of the Acoustical Society of America, 2, 122, 1238-1248
Identifier: 240134
doi: doi:10.1121/1.2747202
Keywords: Parameter estimation · Ports and harbors · Pulse width modulation · Transducers · Frequency-modulated signals · Narrowband frequency · Sound pressure level (SPL) · Signal analysis · Acoustic Stimulation · Echolocation · Hearing · Male · Phocoena · Seawater · Sound

Abstract

It is unclear how well harbor porpoises can locate sound sources, and thus can locate acoustic alarms on gillnets. Therefore the ability of a porpoise to determine the location of a sound source was determined. The animal was trained to indicate the active one of 16 transducers in a 16-m -diam circle around a central listening station. The duration and received level of the narrowband frequency-modulated signals (center frequencies 16, 64 and 100 kHz) were varied. The animal's localization performance increased when the signal duration increased from 600 to 1000 ms. The lower the received sound pressure level (SPL) of the signal, the harder the animal found it to localize the sound source. When pulse duration was long enough (≈1 s) and the received SPLs of the sounds were high (34-50 dB above basic hearing thresholds or 3-15 dB above the theoretical masked detection threshold in the ambient noise condition of the present study), the animal could locate sounds of the three frequencies almost equally well. The porpoise was able to locate sound sources up to 124° to its left or right more easily than sounds from behind it. © 2007 Acoustical Society of America.