|Title:||Anatomy of the odontocete tympano-periotic complex in regard to sound conduction|
|Authors:||March, Duan Tomas|
Bone conducted vibrations
|Publisher:||University of Sydney.|
Faculty of Veterinary Science.
|Abstract:||This aim of this thesis was to examine the auditory anatomy of odontocetes, with a particular focus on Cuvier’s beaked whale (Ziphius cavirostris) to determine if there are any anatomical features unique to this species that may be of functional significance. Cuvier’s beaked whale was the prime species of interest in this study given the over representation of this species at atypical stranding events associated with the use of naval sonar. Features traditionally described in odontocete sound reception and anatomical features that are involved with cochlear stimulation via bone conducted vibrations in terrestrial mammals were examined with computed and micro-computed tomography. The morphology of the Z. cavirostris varied from other odontocetes examined, with a decrease in the size of the tympanic plate and medial sulcus of the mallear ridge. Given the role credited to these structures in odontocete sound conduction, this diminution may decrease the efficiency at which vibrations are transferred via these structures. There was also an increased degree of osseous contact between the tympanoperiotic complex and the skull and an increase in the diameter, and decreased impedance, of the cochlear aqueduct. These features may increase the sensitivity of the cochlea of Z. cavirostris to stimulation via bone conducted vibrations via the direct transfer of cranial vibrations to the periotic bone and the conduction of audio-frequency pressure waves from the cerebrospinal fluid to the cochlea via the cochlear aqueduct. The simultaneous presence and phase differences of these routes of BCV may provide a supra sensitivity to cochlear stimulation at low and mid frequencies and create an interaural intensity difference that may form the basis for an exciting novel hypothesis to explain directional hearing via bone conducted vibrations.|
|Type of Work:||Masters Thesis|
|Type of Publication:||M.V. Sc.|
|Appears in Collections:||Sydney Digital Theses (Open Access)|
|march_dt_thesis.pdf||Thesis||1.39 MB||Adobe PDF|
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