Scaling of the cetacean middle ear

Nummela, Sirpa; Wägar, Thomas; Hemilä, Simo; Reuter, Tom

doi:10.1016/s0378-5955(99)00054-4

Cited by 62 publications

(61 citation statements)

References 20 publications

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“…Mandibles from modern cetaceans were also studied. Comparative data on modern mammalian ears is based on Nummela (1995) and Nummela et al (1999bNummela et al ( , 2004a, as well as new measurements (Table 1). The analysis presented here for the pakicetid hearing mechanisms is based on a large collection of cranial material of pakicetids described by Nummela et al (2004aNummela et al ( , 2006; descriptions for mandibles can be found in Thewissen and Hussain (1998).…”

Section: Methodsmentioning

confidence: 99%

“…The contact between the tympanic bone and the periotic bone (Per) is reduced (PeTy), and thin bony ridges occur on the tympanic side (see computed tomography scans in Nummela et al 1999a). The whole tympanoperiotic complex is pachyosteosclerotic with a density higher than that found in any other mammal: 2.7 g/cm 3 (Giraud-Sauveur, 1969; Lees et al, 1983;Nummela et al, 1999b). This bony complex is acoustically isolated from the skull through air sinuses (Sin) between the periotic and the other skull bones (Sk).…”

Section: Modern Odontocete Ear and Hearingmentioning

confidence: 99%

“…The tympanic membrane and the tympanic plate area were determined using a method described by Nummela (1995) and Nummela et al (1999b), respectively. A Dyer gauge caliper (301-204) was used to measure thickness of the tympanic plate.…”

Section: Parameters Measuredmentioning

confidence: 99%

See 2 more Smart Citations

Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing

Nummela

Thewissen

Bajpai

et al. 2007

The Anatomical Record

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104

111

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The whale ear, initially designed for hearing in air, became adapted for hearing underwater in less than ten million years of evolution. This study describes the evolution of underwater hearing in cetaceans, focusing on changes in sound transmission mechanisms. Measurements were made on 60 fossils of whole or partial skulls, isolated tympanics, middle ear ossicles, and mandibles from all six archaeocete families. Fossil data were compared with data on two families of modern mysticete whales and nine families of modern odontocete cetaceans, as well as five families of noncetacean mammals. Results show that the outer ear pinna and external auditory meatus were functionally replaced by the mandible and the mandibular fat pad, which posteriorly contacts the tympanic plate, the lateral wall of the bulla. Changes in the ear include thickening of the tympanic bulla medially, isolation of the tympanoperiotic complex by means of air sinuses, functional replacement of the tympanic membrane by a bony plate, and changes in ossicle shapes and orientation. Pakicetids, the earliest archaeocetes, had a land mammal ear for hearing in air, and used bone conduction underwater, aided by the heavy tympanic bulla. Remingtonocetids and protocetids were the first to display a genuine underwater ear where sound reached the inner ear through the mandibular fat pad, the tympanic plate, and the middle ear ossicles. Basilosaurids and dorudontids showed further aquatic adaptations of the ossicular chain and the acoustic isolation of the ear complex from the skull. The land mammal ear and the generalized modern whale ear are evolutionarily stable configurations, two ends of a process where the cetacean mandible might have been a keystone character.

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Section: Methodsmentioning

confidence: 99%

Section: Modern Odontocete Ear and Hearingmentioning

confidence: 99%

See 1 more Smart Citation

Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing

Nummela

Thewissen

Bajpai

et al. 2007

The Anatomical Record

Self Cite

104

111

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show abstract

“…The density of all three ossicles has been previously measured by Nummela et al (1999) for six mysticete species (Balaenoptera borealis, Balaenoptera physalus, Balaenoptera musculus, Megaptera novaeangliae, Eubalaena glacialis, and Balaena mysticetus). Since the values do not change significantly between any of the species, an average value for each ossicle was used for each respective ossicle in the minke whale model.…”

Section: Densitymentioning

confidence: 99%

A prediction of the minke whale (Balaenoptera acutorostrata) middle-ear transfer function

Tubelli

Zosuls

Ketten

et al. 2012

The Journal of the Acoustical Society of America

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The lack of baleen whale (Cetacea Mysticeti) audiograms impedes the assessment of the impacts of anthropogenic noise on these animals. Estimates of audiograms, which are difficult to obtain behaviorally or electrophysiologically for baleen whales, can be made by simulating the audiogram as a series of components representing the outer, middle, and inner ear (Rosowski, 1991;Ruggero and Temchin, 2002). The middle-ear portion of the system can be represented by the middle-ear transfer function (METF), a measure of the transmission of acoustic energy from the external ear to the cochlea. An anatomically accurate finite element model of the minke whale (Balaenoptera acutorostrata) middle ear was developed to predict the METF for a mysticete species. The elastic moduli of the auditory ossicles were measured by using nanoindentation. Other mechanical properties were estimated from experimental stiffness measurements or from published values. The METF predicted a best frequency range between approximately 30 Hz and 7.5 kHz or between 100 Hz and 25 kHz depending on stimulation location. Parametric analysis found that the most sensitive parameters are the elastic moduli of the glove finger and joints and the Rayleigh damping stiffness coefficient b. The predicted hearing range matches well with the vocalization range.

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“…No published values for the bone densities of the tympanic bulla in the minke whale were found in literature; however, there are published values for all three ossicles for several other cetacean species [9]. The values used for the model were average density values of some rorquals (Balaenoptera borealis, Balaenoptera physalus, Balaenoptera musculus, and Megaptera novaeangliae).…”

Section: Densitymentioning

confidence: 99%

Biomechanical Analysis of Hearing in Whales Using Nanoindentation and the Finite Element Method

Tubelli¹,

Zosuls²,

Ketten³

et al. 2011

AIP Conference Proceedings

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Abstract. The detailed biomechanics of hearing in baleen whales are almost entirely unknown. As a first step to predicting the audiogram for these species, a linear three-dimensional finite-element model of the minke whale (Balaenoptera acutorostrata) middle ear was developed. A reconstruction of the ear was made from CT scans and imported into a finite element solver. Young's modulus of the bone was estimated via nanoindentation. The middle-ear transfer function was estimated by applying a pressure to the glove finger (the thick, everted equivalent of the tympanic membrane) with velocity calculated at the stapes footplate. It was found that the most sensitive frequencies corresponded with vocalization frequencies. For all frequencies tested, the malleus-incus complex flexed about the anterior process of the malleus and the stapes rotated within the oval window. Results indictae that finite element modeling is a useful approach for studying the mechanics of hearing in species that are difficult to study in vivo.

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Scaling of the cetacean middle ear

Cited by 62 publications

References 20 publications

Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing

Sound transmission in archaic and modern whales: Anatomical adaptations for underwater hearing

A prediction of the minke whale (Balaenoptera acutorostrata) middle-ear transfer function

Biomechanical Analysis of Hearing in Whales Using Nanoindentation and the Finite Element Method

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