Recording and Analysis of Dolphin Echolocation Signals

Diercks, K. J.; Trochta, R. T.; Greenlaw, Charles F.; Evans, William E.

doi:10.1121/1.1912569

Cited by 61 publications

(24 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In this study, we report a mean F c and mean F p of 101 and 95 kHz, respectively, which are well above most previously reported frequencies for boto echolocation clicks (Diercks et al, 1971;Nakasai and Takemura, 1975;Kamminga, 1979;Pilleri et al, 1979;Kamminga et al, 1993), but conform with the study by Penner and Murchison on a single boto in captivity (Penner and Murchison, 1970). Many of the previous studies may have suffered from equipment limitations, but even with adequate recording bandwidth, a lack of strict on-axis criteria may explain a large part of the remaining variation given how high frequencies are radiated in narrower beams than lower ones for the same aperture size (Au, 1993).…”

Section: High Frequencies Despite Low Output Levelssupporting

confidence: 77%

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar

Ladegaard

Jensen

Freitas

et al. 2015

Journal of Experimental Biology

View full text Add to dashboard Cite

Toothed whales produce echolocation clicks with source parameters related to body size; however, it may be equally important to consider the influence of habitat, as suggested by studies on echolocating bats. A few toothed whale species have fully adapted to river systems, where sonar operation is likely to result in higher clutter and reverberation levels than those experienced by most toothed whales at sea because of the shallow water and dense vegetation. To test the hypothesis that habitat shapes the evolution of toothed whale biosonar parameters by promoting simpler auditory scenes to interpret in acoustically complex habitats, echolocation clicks of wild Amazon river dolphins were recorded using a vertical seven-hydrophone array. We identified 404 on-axis biosonar clicks having a mean SL pp of 190.3±6.1 dB re. 1 µPa, mean SL EFD of 132.1±6.0 dB re. 1 µPa 2 s, mean F c of 101.2±10.5 kHz, mean BW RMS of 29.3±4.3 kHz and mean ICI of 35.1±17.9 ms. Piston fit modelling resulted in an estimated half-power beamwidth of 10.2 deg (95% CI: 9.6-10.5 deg) and directivity index of 25.2 dB (95% CI: 24.9-25.7 dB). These results support the hypothesis that river-dwelling toothed whales operate their biosonars at lower amplitude and higher sampling rates than similar-sized marine species without sacrificing high directivity, in order to provide high update rates in acoustically complex habitats and simplify auditory scenes through reduced clutter and reverberation levels. We conclude that habitat, along with body size, is an important evolutionary driver of source parameters in toothed whale biosonars.

show abstract

Section: High Frequencies Despite Low Output Levelssupporting

confidence: 77%

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar

Ladegaard

Jensen

Freitas

et al. 2015

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Changing sound speeds, refraction and reflective air sacs preclude straight line triangulation of sound source locations in the toothed whale forehead (Diercks et al, 1971) but the bilateral symmetry of the porpoise nasal complex (Huggenberger et al, 2009) increases the chance that laterally placed hydrophones in line with the phonic lips have the same sound paths to each of their phonic lip pairs. This implies that simultaneous actuation of both pairs in the formation of a click (Cranford et al, 1996;Lammers and Castellote, 2009) should lead to the same time of arrival at the two receiving hydrophones in porpoises.…”

Section: Discussionmentioning

confidence: 99%

“…To avoid the problem of interpreting far field recordings around the head, we used suction cup hydrophones for near-field sound recordings (sensu Diercks, et al, 1971;Au et al, 2006) to test if there were one or two pairs of phonic lips active during sound production. Changing sound speeds, refraction and reflective air sacs preclude straight line triangulation of sound source locations in the toothed whale forehead (Diercks et al, 1971) but the bilateral symmetry of the porpoise nasal complex (Huggenberger et al, 2009) increases the chance that laterally placed hydrophones in line with the phonic lips have the same sound paths to each of their phonic lip pairs.…”

Section: Discussionmentioning

confidence: 99%

Single source sound production and dynamic beam formation in echolocating harbour porpoises (Phocoena phocoena)

Madsen

Wisniewska

Beedholm

2010

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYEcholocating toothed whales produce high-powered clicks by pneumatic actuation of phonic lips in their nasal complexes. All non-physeteroid toothed whales have two pairs of phonic lips allowing many of these species to produce both whistles and clicks at the same time. That has led to the hypothesis that toothed whales can increase the power outputs and bandwidths of clicks, and enable fast clicking and beam steering by acutely timed actuation of both phonic lip pairs simultaneously. Here we test that hypothesis by applying suction cup hydrophones on the sound-producing nasal complexes of three echolocating porpoises (Phocoena phocoena) with symmetrical pairs of phonic lips. Using time of arrival differences on three hydrophones, we show that all recorded clicks from these three porpoises are produced by the right pair of phonic lips with no evidence of simultaneous or independent actuation of the left pair. It is demonstrated that porpoises, despite actuation of only one sound source, can change their output and sound beam probably through conformation changes in the sound-producing soft tissues and nasal sacs, and that the coupling of the phonic lips and the melon acts as a waveguide for sound energy between 100 and 160kHz to generate a forward-directed sound beam for echolocation.

show abstract

“…Later, it was shown that most soundsare produced in the nasal region (Diercks et al, 1971;Hollien et al, 1976;Dormer, 1979;Mackay and Liaw, 1981;Amundin and Andersen, 1983), but the exact location and mechanism remained unknown. In 1997, Cranford and colleagues described results of using an endoscopy to examine sound generation in a bottlenose dolphin (Tursiops truncatus).…”

Section: Echolocation and Sound Sourcesmentioning

confidence: 99%

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Barroso¹,

Cranford²,

Berta³

2012

Journal of Morphology

View full text Add to dashboard Cite

Odontocete mandibles serve multiple functions, including feeding and hearing. One hypothesis is that sound enters the hearing apparatus via the pan bone of the posterior mandibles (Norris, 1968). Another viewpoint, based on computer models, suggests that sound enters primarily through the gular apparatus and the opening created by the absent medial wall of the posterior mandibles. The posterior region of each mandibular ramus has a large, hollow cavity called the mandibular foramen that contains a bulging mandibular fat body (MFB), which terminates on the bony tympanoperiotic complex. The acoustic properties of these fat bodies suggest that they refract sound. This unambiguous link between form and function has catalyzed this current study of mandibular shape. Previous studies have described odontocete mandibles using linear morphometrics and focused on multiple populations within single genera. Geometric Morphometrics (GM) is used to avoid some limitations of linear morphometric studies, using relative 3-D landmark positions instead of lengths. This technique measures shape only, excluding any scaling, rotational, and positional effects.The primary objective of this study is to use GM to quantify mandibular shape across all major lineages of Odontoceti. Eighty-five mandibles, comprised of 40 species, representing all major lineages were included in the shape analysis. Twelve landmarks found on each mandible represent regions of the symphysis and mandibular foramen. The majority of shape variation was found in Jaw Flare and Symphysis Elongation (85.5%). Shape differences in the mandibular foramen also accounts for a portion the total variation (10.9%). The mandibles are an integral component of the sound reception apparatus in toothed whales and the geometry of the mandibular foramen likely plays a role in hearing.The second objective of this study is to assess correlates of hearing and mandibular foramen geometry derived from the GM shape analysis, as well as from linear morphometrics. Echolocation peak frequency (EPF) was used as a measure of sound reception. Odontocete anatomy may emphasize frequencies they need to hear and suppress others in a returning echo during echolocation. Frequencies can be characterized by corresponding wavelengths. Surface area between the four landmarks that represent the mandibular foramen was calculated to assess the relationship between EPF and dimensions of a receiving structure (i.e. mandibular foramen and corresponding MFB). A significant relationship between size of the foramen and EPF was found, suggesting that size of the foramen may limit lower frequencies (longer wavelengths) from propagating through the mandibular fat body.

show abstract

Recording and Analysis of Dolphin Echolocation Signals

Cited by 61 publications

References 0 publications

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar

Amazon river dolphins (Inia geoffrensis) use a high-frequency short-range biosonar

Single source sound production and dynamic beam formation in echolocating harbour porpoises (Phocoena phocoena)

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Contact Info

Product

Resources

About