Echolocation signals of Heaviside's dolphins ( Cephalorhynchus heavisidii )

Field recordings of echolocation signals produced by Heaviside's dolphins ( Cephalorhynchus heavisidii ) were made off the coast of South Africa using a hydrophone array system. The system consisted of three hydrophones and an A-tag (miniature stereo acoustic data-logger). The mean centroid fre...

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Bibliographic Details
Published in:The Journal of the Acoustical Society of America 2011, Vol.129 (1), p.449-457
Main Authors: Morisaka, Tadamichi, Karczmarski, Leszek, Akamatsu, Tomonari, Sakai, Mai, Dawson, Steve, Thornton, Meredith
Format: Article
Language:English
Subjects:
Acoustic signal processing
Acoustics
Acoustics - instrumentation
Animals
Cephalorhynchus
Cephalorhynchus heavisidii
Cetacea
Dolphins - physiology
Echolocation
Exact sciences and technology
Fundamental areas of phenomenology (including applications)
Physics
Pressure
Signal Processing, Computer-Assisted
Sound
Sound Spectrography
Time Factors
Transducers
Underwater sound
Vocalization, Animal
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Summary:Field recordings of echolocation signals produced by Heaviside's dolphins ( Cephalorhynchus heavisidii ) were made off the coast of South Africa using a hydrophone array system. The system consisted of three hydrophones and an A-tag (miniature stereo acoustic data-logger). The mean centroid frequency was 125 kHz, with a −3 dB bandwidth of 15 kHz and −10 dB duration of 74 μ s. The mean back-calculated apparent source level was 173 dB re 1 μ Pa p.-p. . These characteristics are very similar to those found in other Cephalorhynchus species, and such narrow-band high-frequency echolocation clicks appear to be a defining characteristic of the Cephalorhynchus genus. Click bursts with very short inter-click intervals (up to 2 ms) were also recorded, which produced the "cry" sound reported in other Cephalorhynchus species. Since inter-click intervals correlated positively to click duration and negatively to bandwidth, Heaviside's dolphins may adjust their click duration and bandwidth based on detection range. The bimodal distribution of the peak frequency and stable bimodal peaks in spectra of individual click suggest a slight asymmetry in the click production mechanism.
ISSN:0001-4966
1520-8524
DOI:10.1121/1.3519401