Scaling of the marsupial middle ear and its functional significance

Title

Scaling of the marsupial middle ear and its functional significance

Creator

Nummela S; Sanchez-Villagra M R

Publisher

Journal of Zoology

Date

2006
2006-10

Description

The marsupial middle ear performs an anatomical impedance matching for acoustic energy travelling in air to reach the cochlea. The size of the middle ear sets constraints for the frequencies transmitted. For generalized placental mammals, it has been shown that the limit for high-frequency hearing can be predicted on the basis of middle ear ossicle mass, provided that the ears fulfil requirements of isometry. We studied the interspecific size variation of the middle ear in 23 marsupial species, with the following measurable parameters: skull mass, condylobasal length, ossicular masses for malleus, incus and stapes, tympanic membrane area, oval window area, and lever arm lengths for malleus and incus. Our results show that the middle ear size grows with negative allometry in relation to body size and that the internal proportions of the marsupial middle ear are largely isometric. This resembles the situation in placental mammals and allows us to use their isometric middle ear model to predict the high-frequency hearing limit for marsupials. We found that the isometry model predicts the high-frequency hearing limit for different marsupials well, indicating that marsupials can be used as auditory models for general therian mammalian hearing. At very high frequencies, other factors, such as the inner ear, seem to constrain mammalian hearing.

Subject

absolute; allometry; auditory characteristics; evolution; hearing; hearing sensitivity; impedance; mammal; marsupial; middle ear; mongolian gerbil; monodelphis-domestica; primitive mammals; pure-tone thresholds; size; trichosurus-vulpecula; Zoology

Format

Journal Article

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Rights

Article information provided for research and reference use only. All rights are retained by the journal listed under publisher and/or the creator(s).

Pages

256-267

Issue

2

Volume

270

Citation

Nummela S; Sanchez-Villagra M R, “Scaling of the marsupial middle ear and its functional significance,” NEOMED Bibliography Database, accessed October 18, 2021, https://neomed.omeka.net/items/show/6671.

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