Mechanism of sound production and air recycling in delphinids: Cineradiographic evidence

Dormer, Kenneth J.

doi:10.1121/1.382240

Cited by 75 publications

(70 citation statements)

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“…During a typical click train, the subject's source levels followed a stereotypical pattern, starting at low source levels, increasing to a maximum, and then decreasing towards the end of the click train (Fig.3). This pattern is common for echolocating odontocetes (Au et al, 1974;Au et al, 1987) and is thought to be a result of the pneumatic generating process (Norris and Harvey, 1972;Dormer, 1979;Ridgway et al, 1980;Amundin and Andersen, 1983). The whale also used a scanning motion with her head and echolocation beam, clicking first off-axis, then directly on the target, and again scanning off-axis.…”

Section: Methodsmentioning

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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Section: Methodsmentioning

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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“…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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“…Whistles and burst-pulsed sounds can be produced simultaneously (Janik, 2009). This corresponds with the generally accepted concept that there are two sites of sound production that can be controlled independently (Dormer, 1979). They are composed of two identical sound producing structures consisting of fatty dorsal bursae within a pair of phonic lips, one in the left and one in the right nasal passage (Cranford et al, 1996).…”

Section: Behavioral Data On Auditionmentioning

confidence: 99%

Sensory Perception in Cetaceans: Part I—Current Knowledge about Dolphin Senses As a Representative Species

et al. 2016

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A large part of the literature on sensory perception and behavior in dolphins is devoted to its well-developed vocal and echolocation abilities. In this review, we aim to augment current knowledge by examining the literature on dolphins' entire "Merkwelt" (which refers to everything a subject perceives, creating a crucial part of the subject's Umwelt). We will show that despite extensive knowledge on audition, aspects such as context relatedness, the social function of vocalizations or socio-sexual recognition, remain poorly understood. Therefore, we propose areas for further lines of investigation. Recent studies have shown that the sensory world of dolphins might well be much more diverse than initially thought. Indeed, although underwater and aerial visual systems differ in dolphins, they have both been shown to be important. Much debated electro-and magnetoreception appear to be functional senses according to recent studies. Finally, another neglected area is chemoreception. We will summarize neuroanatomical and physiological data on olfaction and taste, as well as corresponding behavioral evidence. Taken together, we will identify a number of technical and conceptual reasons for why chemosensory data appear contradictory, which is much debated in the literature. In summary, this article aims to provide both an overview of the current knowledge on dolphin perception, but also offer a basis for further discussion and potential new lines of research.Keywords: cetaceans, Delphinidae, Tursiops truncatus, audition, vision, electroreception, magnetoreception, chemoreception DOLPHIN'S UMWELT Sensory perception is essential for the survival of organisms, be it for the detection of (un)favorable physical conditions, the presence/absence of food or predators, the detection of communication signals or the recognition of social partners. It is crucial for any species to perceive regularities and changes in the properties of their abiotic and biotic environment.

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Mechanism of sound production and air recycling in delphinids: Cineradiographic evidence

Cited by 75 publications

References 0 publications

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

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

Shape analysis of odontocete mandibles: Functional and evolutionary implications

Sensory Perception in Cetaceans: Part I—Current Knowledge about Dolphin Senses As a Representative Species

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