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  • 1
    Online Resource
    Online Resource
    The Company of Biologists ; 2007
    In:  Journal of Experimental Biology Vol. 210, No. 1 ( 2007-01-01), p. 56-64
    In: Journal of Experimental Biology, The Company of Biologists, Vol. 210, No. 1 ( 2007-01-01), p. 56-64
    Abstract: Field recordings of harbour porpoises (Phocoena phocoena) were made in the inner Danish waters with a vertical array of three or four hydrophones. The back-calculated source level ranged from 178 to 205 dB re 1μPa pp @ 1 m with a mean source level of 191 dB re 1 μPa pp @ 1 m. The maximum source level was more than 30 dB above what has been measured from captive animals, while the spectral and temporal properties were comparable. Calculations based on the sonar equation indicate that harbour porpoises,using these high click intensities, should be capable of detecting fish and nets and should be detectable by porpoise detectors over significantly larger distances than had previously been assumed. Harbour porpoises in this study preferred a relatively constant inter-click interval of about 60 ms, but intervals up to 200 ms and down to 30 ms were also recorded.
    Type of Medium: Online Resource
    ISSN: 1477-9145 , 0022-0949
    Language: English
    Publisher: The Company of Biologists
    Publication Date: 2007
    detail.hit.zdb_id: 1482461-9
    SSG: 12
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  • 2
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 130, No. 4 ( 2011-10-01), p. 2263-2274
    Abstract: The Indian Ocean and Atlantic bottlenose dolphins (Tursiops aduncus and Tursiops truncatus) are among the best studied echolocating toothed whales. However, almost all echolocation studies on bottlenose dolphins have been made with captive animals, and the echolocation signals of free-ranging animals have not been quantified. Here, biosonar source parameters from wild T. aduncus and T. truncatus were measured with linear three- and four-hydrophone arrays in four geographic locations. The two species had similar source parameters, with source levels of 177–228 dB re 1 μPa peak to peak, click durations of 8–72 μs, centroid frequencies of 33–109 kHz and rms bandwidths between 23 and 54 kHz. T. aduncus clicks had a higher frequency emphasis than T. truncatus. The transmission directionality index was up to 3 dB higher for T. aduncus (29 dB) as compared to T. truncatus (26 dB). The high directionality of T. aduncus does not appear to be only a physical consequence of a higher frequency emphasis in clicks, but may also be caused by differences in the internal properties of the sound production system.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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