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Proceedings Paper

Measurement of basilar membrane motion in the turtle with laser-feedback interferometry
Author(s): Michael P. O'Neill; Alan J. Bearden
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Paper Abstract

In mammalian hearing, the frequency-dependent spatial pattern of movement in the basilar membrane (BM) forms the basis of frequency discrimination (tuning). This is not necessarily the case in lower vertebrates; the turtle, for example, has an electrical resonance mechanism in its auditory receptor cells that varies in best frequency from cell-to-cell along the underlying BM. But how much, if any, of the frequency separation by this reptile is done mechanically by its BM? In other animals, vibrational analyses were indirect in that they required the placement of nonphysiological objects on the BM (e.g., the radioactive source of the Mossbaurer technique or the mirror of traditional laser interferometry). Our attempt to find an alternative approach led to the rediscovery of laser-feedback interferometry (LFI), here applied for the first time to vibration analysis in a biological system. LFI is an ideal method to directly measure the nanometer motion (amplitude and phase) of diffuse scattering surfaces such as the BM because of its simple geometry, ease of alignment, and its ability to respond to surfaces with a broad range of reflectances (10-6 to 1). Preliminary LFI investigations of BM motion in the turtle reveal that its BM is broadly tuned and mainly reflects middle ear filter characteristics. No evidence for frequency-selective spatial BM mechanical tuning was found.

Paper Details

Date Published: 3 September 1993
PDF: 11 pages
Proc. SPIE 1889, Holography, Interferometry, and Optical Pattern Recognition in Biomedicine III, (3 September 1993); doi: 10.1117/12.155724
Show Author Affiliations
Michael P. O'Neill, Univ. of California/Berkeley (United States)
Alan J. Bearden, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 1889:
Holography, Interferometry, and Optical Pattern Recognition in Biomedicine III
Halina Podbielska M.D., Editor(s)

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