Topography of vibration frequency responses on the bony tympano-periotic complex of the pilot whale Globicephala macrorhynchus.

Autor: Tsur I; Faculty of Biological and Environmental Sciences, University of Helsinki, 00014 Helsinki, Finland. Electronic address: itsur2@gmail.com., Shaviv N; Racah Institute of Physics The Hebrew University of Jerusalem, 91904 Jerusalem, Israel., Bronstein I; Department of Mechanical Engineering, Ben Gurion University, Beer Sheva, Israel., Elmakis D; Department of Mechanical Engineering, Ben Gurion University, Beer Sheva, Israel., Knafo O; Department of Mechanical Engineering, Ben Gurion University, Beer Sheva, Israel., Werner YL; Department of Ecology, Evolution and Behaviour, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel; Museum für Tierkunde, Senckenberg Dresden, Königsbrücker Landstrasse 159, D-01109 Dresden, Germany.
Jazyk: angličtina
Zdroj: Hearing research [Hear Res] 2019 Dec; Vol. 384, pp. 107810. Date of Electronic Publication: 2019 Oct 10.
DOI: 10.1016/j.heares.2019.107810
Abstrakt: In modern Cetacea, the ear bone complex comprises the tympanic and periotic bones forming the tympano-periotic complex (TPC), differing from temporal bone complexes of other mammals in form, construction, position, and possibly function. To elucidate its functioning in sound transmission, we studied the vibration response of 32 pairs of formaldehyde-glutaraldehyde-fixed TPCs of Globicephala macrorhynchus, the short-finned pilot whale (legally obtained in Taiji, Japan). A piezoelectric-crystal-based vibrator was surgically attached to a location on the cochlea near the exit of the acoustic nerve. The crystal delivered vibrational pulses through continuous sweeps from 5 to 50 kHz. The vibration response was measured as a function of frequency by Laser Doppler Vibrometry at five points on the TPC. The aim of the experiment was to clarify how the vibration amplitudes produced by different frequencies are distributed on the TPC. At the lowest frequencies (<12 kHz), no clear differential pattern emerged. At higher frequencies the anterolateral lip of the TP responded most sensitively with the highest displacement amplitudes, and response amplitudes decreased in orderly fashion towards the posterior part of the TPC. We propose that this works as a lever: high-frequency sounds are most sensitively received and cause the largest vibration amplitudes at the anterior part of the TP, driving movements with lower amplitude but greater force near the posteriorly located contact to the ossicular chain, which transmits the movements into the inner ear. Although force (pressure) amplification is not needed for impedance matching in water, it may be useful for driving the stiffly connected ossicles at the high frequencies used in echolocation.
(Copyright © 2019 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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