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A Portable Matched-Field Processing System Using Passive Acoustic Time Synchronization
"... Abstract—A portable matched-field processing (MFP) system for tracking marine mammals is presented, constructed by attaching a set of autonomous flash-memory acoustic recorders to a rope to form a four-element vertical array, or “insta-array.” The acoustic data are initially time-synchronized by per ..."
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Abstract—A portable matched-field processing (MFP) system for tracking marine mammals is presented, constructed by attaching a set of autonomous flash-memory acoustic recorders to a rope to form a four-element vertical array, or “insta-array.” The acoustic data are initially time-synchronized by performing a matched-field global inversion using acoustic data from an opportunistic source, and then by exploiting the spatial coherence of the ocean ambient noise background to measure and correct for the relative clock drift between the autonomous recorders. The technique is illustrated by using humpback whale song collected off the eastern Australian coast to synchronize the array, which is then used to track the dive profile of the whale using MFP methods. The ability to deploy autonomous instruments into arbitrary “insta-array ” geometries with conventional fishing gear may permit nonintrusive array measurements in regions currently too isolated, expensive, or environmentally hostile for standard acoustic equipment. Index Terms—Acoustic arrays, acoustic beam steering, marine animals, underwater acoustic arrays, underwater acoustics, underwater technology. I.
Blue Whale Calling In The Rottnest Trench
, 2001
"... Through January-April 2000 research was carried out off the Rottnest trench to search for blue or pygmy blue whales. A consortium of researchers carried out aerial surveys, boat surveys and acoustical measures. Historical records led us to believe that a Western Australian population of pygmy blue w ..."
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Through January-April 2000 research was carried out off the Rottnest trench to search for blue or pygmy blue whales. A consortium of researchers carried out aerial surveys, boat surveys and acoustical measures. Historical records led us to believe that a Western Australian population of pygmy blue whales (Balaenopteridae musculus brevicauda, sub species of the true blue whale, B. m. musculus) existed, while a preliminary boat survey in 1994 suggested that some of these animals aggregated in the Rottnest trench west of Perth. This was confirmed in the 2000 observations, aerial surveys sighted up to eight blue whales/flight within the trench and in 30 days boat searching 17 blue whales were sighted. Five thousand acoustic records were made, many of which had blue whale calling in, some having up to nine animals calling at once. Although of a slightly different format, the calls recorded were of a similar character to those described from other blue whale populations. A call comprised three components, the first (type I) dominated by a 19 Hz tone for 21 s followed by a jump to a 21 Hz tone for a further 22 s. Five to ten s later the second component (II) followed which was dominated by a long frequency upsweep, beginning near 20 Hz and increasing to 26 Hz over 23 s. Approximately 23 s later the third component followed, this dominated by a 20 s, 19 Hz tone. Harmonics were evident in each component. At least one secondary source was evident in all components, consisting of a pulsed 65 Hz signal. This was especially strong in the type III component. A call thus totalled around two minutes, repeated at intervals of 78 s. The type II component had the highest source level and was the most obvious signal received at long range. Propagation modelling indicated that the componen...
Ecosystem Scale Acoustic Sensing Reveals Humpback Whale Behavior Synchronous with Herring Spawning Processes and Re-Evaluation Finds No Effect of Sonar on Humpback Song Occurrence in the Gulf of Maine in Fall
"... We show that humpback-whale vocalization behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of Maine. With a passive, wide-aperture, densely-sampled, coherent hydrophone array towed north of Georges Bank in a Fall 2006 Ocean Acoustic Waveguide Remote Sensing (OA ..."
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We show that humpback-whale vocalization behavior is synchronous with peak annual Atlantic herring spawning processes in the Gulf of Maine. With a passive, wide-aperture, densely-sampled, coherent hydrophone array towed north of Georges Bank in a Fall 2006 Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment, vocalizing whales could be instantaneously detected and localized over most of the Gulf of Maine ecosystem in a roughly 400-km diameter area by introducing array gain, of 18 dB, orders of magnitude higher than previously available in acoustic whale sensing. With humpback-whale vocalizations consistently recorded at roughly 2000/day, we show that vocalizing humpbacks (i) were overwhelmingly distributed along the northern flank of Georges Bank, coinciding with the peak spawning time and location of Atlantic herring, and (ii) their overall vocalization behavior was strongly diurnal, synchronous with the formation of large nocturnal herring shoals, with a call rate roughly ten-times higher at night than during the day. Humpback-whale vocalizations were comprised of (1) highly diurnal non-song calls, suited to hunting and feeding behavior, and (2) songs, which had constant occurrence rate over a diurnal cycle, invariant to diurnal herring shoaling. Before and during OAWRS survey transmissions: (a) no vocalizing whales were found at Stellwagen Bank, which had negligible herring populations, and (b) a constant humpback-whale song occurrence rate indicates the transmissions had no effect on humpback song. These measurements contradict the conclusions of Risch et al. Our analysis indicates that (a) the song occurrence variation
and Indian Ocean stocks
, 2013
"... ePublications@SCU is an electronic repository administered by Southern Cross University Library. Its goal is to capture and preserve the intellectual output of Southern Cross University authors and researchers, and to increase visibility and impact through open access to researchers around the world ..."
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ePublications@SCU is an electronic repository administered by Southern Cross University Library. Its goal is to capture and preserve the intellectual output of Southern Cross University authors and researchers, and to increase visibility and impact through open access to researchers around the world. For further information please contact
Source levels of social sounds in migrating humpback whales (Megaptera novaeangliae)
"... The source level of an animal sound is important in communication, since it affects the distance over which the sound is audible. Several measurements of source levels of whale sounds have been reported, but the accuracy of many is limited because the distance to the source and the acoustic transmi ..."
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The source level of an animal sound is important in communication, since it affects the distance over which the sound is audible. Several measurements of source levels of whale sounds have been reported, but the accuracy of many is limited because the distance to the source and the acoustic transmission loss were estimated rather than measured. This paper presents measurements of source levels of social sounds (surface-generated and vocal sounds) of humpback whales from a sample of 998 sounds recorded from 49 migrating humpback whale groups. Sources were localized using a wide baseline five hydrophone array and transmission loss was measured for the site. Social vocalization source levels were found to range from 123 to 183 dB re 1 lPa @ 1 m with a median of 158 dB re 1 lPa @ 1 m. Source levels of surface-generated social sounds ("breaches" and "slaps") were narrower in range (133 to 171 dB re 1 lPa @ 1 m) but slightly higher in level (median of 162 dB re 1 lPa @ 1 m) compared to vocalizations. The data suggest that group composition has an effect on group vocalization source levels in that singletons and mother-calf-singing escort groups tend to vocalize at higher levels compared to other group compositions.
Humpback Whale Song or Humpback Whale Sonar? A Reply to Au et al.
"... Abstract—Au and colleagues ’ arguments against the hypothesis that humpback whale songs function as long-range sonar are based on questionable assumptions rather than on empirical data. Like other echolocating mammals (e.g., bats), singing humpback whales: 1) localize targets in the absence of visua ..."
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Abstract—Au and colleagues ’ arguments against the hypothesis that humpback whale songs function as long-range sonar are based on questionable assumptions rather than on empirical data. Like other echolocating mammals (e.g., bats), singing humpback whales: 1) localize targets in the absence of visual information; 2) possess a highly innervated peripheral auditory system; and 3) modulate the temporal and spectral features of their sounds based on environmental conditions. The sonar equation is inadequate for determining whether humpback whale songs generate detectable echoes from other whales because it does not account for temporal variables that can strongly affect the detectability of echoes. In particular, the sonar equation ignores the fact that much of the noise encountered by singing humpback whales is spectrally and temporally predictable, and that audition in mammals is a dynamic and plastic process. Experiments are needed to test the hypothesis that singing humpback whales listen for and respond to echoes generated by their songs. Index Terms—Baleen whale, cetacean, environmentally-adaptive sonar, low-frequency sonar, mysticete.
iii
, 2013
"... Site specific passive acoustic detection and densities of humpback whale calls off the coast of California ..."
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Site specific passive acoustic detection and densities of humpback whale calls off the coast of California
unknown title
, 2011
"... Quantifying year around changes in a humpback whale (Megaptera novaeangliae) song sound using multivariate statistics and artificial neural networks ..."
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Quantifying year around changes in a humpback whale (Megaptera novaeangliae) song sound using multivariate statistics and artificial neural networks
