Propagation of Beluga Echolocation Signals

Au, Whitlow W. L.; Penner, Ralph H.; Turl, Charles W.

doi:10.1007/978-1-4684-7493-0_4

Cited by 20 publications

(42 citation statements)

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“…Given the narrow beam TABLE IV. Acoustic transmission characteristics of P. phocoena (Au et al, 1999), H. ampullatus (Wahlberg et al, 2011), M. densirostris (this paper), Z. cavirostris , Pseudorca crassidens (Au et al, 1995;Au, 1993), Tursiops truncatus (Au, 1993) and Delphinapterus leucas (Au, 1993;Au et al, 1987). H. ampullatus, M. densirostris, and Z. cavirostris DI and beam width estimated by fitting piston model to measured ASL.…”

Section: Discussionmentioning

confidence: 83%

Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring

Shaffer

Moretti

Jarvis

et al. 2013

The Journal of the Acoustical Society of America

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The presence of beaked whales in mass-strandings coincident with navy maneuvers has prompted the development of methods to detect these cryptic animals. Blainville's beaked whales, Mesoplodon densirostris, produce distinctive echolocation clicks during long foraging dives making passive acoustic detection a possibility. However, performance of passive acoustic monitoring depends upon the source level, beam pattern, and clicking behavior of the whales. In this study, clicks recorded from Digital acoustic Tags (DTags) attached to four M. densirostris were linked to simultaneous recordings from an 82-hydrophone bottom-mounted array to derive the source level and beam pattern of the clicks, as steps towards estimating their detectability. The mean estimated on-axis apparent source level for the four whales was 201 dB rms97 . The mean 3 dB beamwidth and directivity index, estimated from sequences of clicks directed towards the far-field hydrophones, were 13 and 23 dB, respectively. While searching for prey, Blainville's beaked whales scan their heads horizontally at a mean rate of 3.6 /s over an angular range of some þ/À10 . Thus, while the DI indicates a narrow beam, the area of ensonification over a complete foraging dive is large given the combined effects of body and head movements associated with foraging.

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Section: Discussionmentioning

confidence: 83%

Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring

Shaffer

Moretti

Jarvis

et al. 2013

The Journal of the Acoustical Society of America

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show abstract

“…Unfortunately, for NBHF clicks, it is not always possible to tell whether a click was indeed recorded on-axis, and the actual aspect angle may therefore be underestimated when making such a plot. To address that problem and compare with the present data, we therefore carried out a Monte Carlo simulation of the process to estimate the theoretical distribution as it would have looked if the whales were indeed theoretical piston transducers with a 4cm diameter [as is found using values from Au and colleagues (Au et al, 1999) and the circular piston model of Au et al (Au et al, 1987)]. In the Monte Carlo simulation, a theoretical 4cm diameter piston transducer transmitted clicks at angles up to 50 degrees off the acoustic beam and at ranges of 2-15 meters from the array, matching the distances to the recorded animals.…”

Section: Estimation Of Beam Patternmentioning

confidence: 99%

Echolocation in sympatric Peale's dolphins (Lagenorhynchus australis) and Commerson's dolphins (Cephalorhynchus commersonii) producing narrow-band high-frequency clicks

Kyhn

Jensen

Beedholm

et al. 2010

Journal of Experimental Biology

112

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SUMMARY (177±5dB re 1Pa p.-p.). The mean directivity indexes were 25dB for both species. The relatively low source levels in combination with the high directivity index may be an adaptation to reduce clutter when foraging in a coastal environment. We conclude that the small species-specific shifts in distribution of centroid frequencies around 130kHz may reflect character displacement in otherwise-stereotyped NBHF clicks.

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“…Beam patterns have been directly measured under laboratory conditions for Tursiops truncatus (Au et al, 1978;Au et al, 1980;Au et al, 1986), Delphinapteus leucas (Au et al, 1987), Pseudorca crassidens (Au et al, 1995) and Phocoena phocoena (Au et al, 1999), and have been estimated from field recordings of Lagenorhynchus albirostris (Rasmussen at al., 2004), Platanista gangetica (Bahl et al, 2007), Physeter macrocephalus (Mohl et al, 2003) and Ziphius cavirostris (Zimmer et al, 2005a). Most odontocete signals measured thus far have 3dB beamwidths (the angle at which the beam's power is half the maximum power of the signal) between 8 and 15deg, with interspecific and intraspecific variation (Au, 1993).…”

Section: Introductionmentioning

confidence: 99%

Active echolocation beam focusing in the false killer whale, Pseudorca crassidens

Kloepper

Nachtigall

Donahue

et al. 2012

Journal of Experimental Biology

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SUMMARYThe odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete echolocation signals are variable and the emitted click frequency greatly affects the echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.

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Propagation of Beluga Echolocation Signals

Cited by 20 publications

References 0 publications

Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring

Effective beam pattern of the Blainville's beaked whale (Mesoplodon densirostris) and implications for passive acoustic monitoring

Echolocation in sympatric Peale's dolphins (Lagenorhynchus australis) and Commerson's dolphins (Cephalorhynchus commersonii) producing narrow-band high-frequency clicks

Active echolocation beam focusing in the false killer whale, Pseudorca crassidens

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