Dolphin Vocalization Mechanisms

Mackay, R. Stuart; Liaw, H. M.

doi:10.1126/science.212.4495.676

Cited by 53 publications

(32 citation statements)

References 9 publications

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“…Similarly, in their ultrasound Doppler study of bottlenose dolphins, Mackay and Liaw observed vibrations mainly in the right side of the nasal complexes during clicking (Mackay and Liaw, 1981). These earlier findings and the ones made here thus challenge the hypothesis advanced by Lammers and Castellote (Lammers and Castellote, 2009) that double pulse production is universal among echolocating toothed whales.…”

Section: Discussioncontrasting

confidence: 50%

“…They proceed to advance the hypothesis that the double source sound production may be found in all echolocating toothed whales. However, these conclusions are at odds with previous findings (Dormer, 1979;Mackay and Liaw, 1981;Amundin and Andersen, 1983) and modeling efforts (Aroyan et al, 2000) whose results indicate that the right pair of phonic lips is primarily used to produce echolocation clicks. Further, the intrapulse intervals in the Lammers and Castellote study are very long, and hence difficult to reconcile with the physical separation of the two pairs of phonic lips of some 10-15cm and the speed of sound in tissue around 1500ms -1 .…”

Section: Introductioncontrasting

confidence: 56%

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

Madsen

Wisniewska

Beedholm

2010

Journal of Experimental Biology

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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.

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Section: Discussioncontrasting

confidence: 50%

Section: Introductioncontrasting

confidence: 56%

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

Madsen

Wisniewska

Beedholm

2010

Journal of Experimental Biology

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“…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

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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.

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“…In an attempt to investigate whether echolocating porpoises actuate two sources simultaneously for clicking, we used three suction cup hydrophones on the nasal complex of three porpoises to show that they consistently clicked with their right pair of phonic lips, as has been reported from many studies on both porpoises (Amundin and Andersen, 1983;Au et al, 2006) and delphinids (Norris et al, 1971;Dormer, 1979;Mackay and Liaw, 1981;Amundin and Andersen, 1983;Au et al, 2010;Dubrovskiy and Giro, 2004). The melon recordings that we obtained ) also strongly suggested that porpoises can modulate their sound beams with just one source active, presumably by changing the conformation of the nasal soft structures and air sacs.…”

Section: Introductionmentioning

confidence: 99%

Nasal sound production in echolocating delphinids (Tursiops truncatus and Pseudorca crassidens) is dynamic, but unilateral: clicking on the right side and whistling on the left side

Madsen

Lammers²,

Wisniewska

et al. 2013

Journal of Experimental Biology

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SUMMARYToothed whales produce sound in their nasal complex by pneumatic actuation of phonic lip pairs within the blowhole. It has been hypothesized that dual actuation of the phonic lip pairs can generate two pulses that merge to form a single echolocation click with a higher source level, broader bandwidth and larger potential for beam steering than if produced by a single pair of phonic lips. Here, we test that hypothesis by measuring the sound production of five echolocating delphinids using hydrophones around the animals and imbedded in on-animal suction cups. We show that the studied animals click with their right pair of phonic lips and whistle with their left pair. We demonstrate that, with just a single pair of phonic lips, they can change the click energy levels over five orders of magnitude, change the click centroid frequencies over more than two octaves, and modulate the sound radiation from the melon for beam steering. We conclude that all of the click dynamics ascribed to dual actuation of two phonic lip pairs can be achieved with actuation of just the right pair of phonic lips, and we propose that the large dynamic range of source outputs is achieved by highly controlled modulation of the pneumatic driving pressure, the tension of the phonic lip labia and the conformation of the fatty melon and associated air sacs.

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Dolphin Vocalization Mechanisms

Cited by 53 publications

References 9 publications

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

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

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Nasal sound production in echolocating delphinids (Tursiops truncatus and Pseudorca crassidens) is dynamic, but unilateral: clicking on the right side and whistling on the left side

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