Measurement of Basilar Membrane Vibration Using a Scanning Laser Interferometer

Ren, Tao; Zhang, Yan; Zheng, Juanjuan; Nuttall, Alfred L.; Porsov, Edward; Matthews, S.

doi:10.1142/9789812704931_0031

Cited by 3 publications

(3 citation statements)

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“…4). This result is consistent with the experimental observations at the base (18,37). However, this simple upward transverse movement of the BM is associated with a complex vibrational mode of the TM-RL gap at high frequency (Fig.…”

Section: Resultssupporting

confidence: 93%

“…We use ␤ in the following two ways: first, to determine whether a wave propagates, and second, to estimate the characteristic frequency of a cross section. The wave propagates when ␤ is much smaller than 40-50 dB͞mm reported at the cut-off region of the traveling wave (36,37) or the 58 dB͞mm reported for the click response in the hemicochlea (36). The frequency at which ␤ approaches the cut-off value provides an estimate for the characteristic frequency.…”

Section: Resultsmentioning

confidence: 89%

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Evidence of tectorial membrane radial motion in a propagating mode of a complex cochlear model

Cai

Shoelson

Chadwick

2004

Proc. Natl. Acad. Sci. U.S.A.

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Knowledge of vibratory patterns in the cochlea is crucial to understanding the stimulation of mechanosensory cells. Experiments to determine the motion of the cochlear partition and surrounding fluid are extremely challenging. As a result, the motion data are incomplete and often contradictory. The bending mechanism of hair bundles, thought to be related to the shear motion and endolymphatic flow between the tectorial membrane (TM) and reticular lamina (RL), is controversial. We, therefore, extend the frequency range of our previous hybrid analytical-finite-element approach to model the basal as well as apical regions of the guinea pig cochlea. We solve the fluid-solid interaction eigenvalue problem for the axial wavenumber, fluid pressure, and vibratory relative motions of the cochlear partition as a function of frequency. A simple monophasic vibratory mode of the basilar membrane is found at both ends of the cochlea. However, this simple movement is associated with a complex frequency-dependent relative deformation between the TM and the RL. We provide evidence of a radial component of TM motion that is out of phase with the RL and that facilitates the bending of outer hair cell stereocilia at appropriate frequencies at both the cochlear base and apex.A dynamic fluid-structure interaction occurs when the cochlea is stimulated by environmental sounds. This interaction elicits a transverse wave on the cochlear partition (CP), which travels from the base to the apex of the spiral-shaped hearing organ. Details of the vibratory mode shape of this traveling wave are directly related to the bending of hair bundles and, therefore, are very important to the understanding of the stimulation of inner hair cells (IHCs) and outer hair cells (OHCs), which lies at the very core of hearing transduction (1, 2). The tectorial membrane (TM) radial resonance is thought to be one potential bending mechanism of the stereocilia. The origin and evolution of ideas concerning the radial motion of the TM is discussed fully in Zwislocki's recent monograph (3). In short, new ideas were needed to resolve discrepancies in both amplitude and phase of the tuning of mechanical, neural, and cellular responses. TM radial motion, consequently, was incorporated in mathematical models of cochlear micromechanics by using the lumped-parameter approach (1, 3-9). Although indirect evidence inferred from frequency tuning of otoacoustic emissions (10, 11) and cochlear microphonics (12) lent support to the idea of radial TM motion, direct evidence awaited the measurements of Gummer et al. (13) and Hemmert et al. (14). These latter findings contrast those of Ulfendahl et al. (15), who reported almost no radial motion of the TM. Preliminary observations of TM motion in the hemicochlea preparation also do not yet show a significant TM radial motion (16,17). It seems that the local excitation in that preparation has difficulty in exciting a significantly propagating mode, which could affect the TM motion.Another controversy involves the transverse mode shape...

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 89%

Evidence of tectorial membrane radial motion in a propagating mode of a complex cochlear model

Cai

Shoelson

Chadwick

2004

Proc. Natl. Acad. Sci. U.S.A.

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“…Although each OHC acts as a circular wave source, their linear arrangement effectively produces a nearly linear wavefront parallel to the OHC rows, and in this way an escaping wave propagates at right angles to the rows and towards the IHCs. Some experiments 18,19 have seen large phase variations across the partition ͑up to 180°between points 10 m apart 18 ͒, which can be interpreted as good evidence for short wavelength radial wave motion; however others 20 have seen no radial phase variability, so that more work is needed to clarify this behavior.…”

Section: The Cochlear Amplifier As a Standing Wave?mentioning

confidence: 99%

The cochlear amplifier as a standing wave: “Squirting” waves between rows of outer hair cells?

Bell

Fletcher

2004

The Journal of the Acoustical Society of America

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This paper draws attention to symmetric Lloyd-Redwood (SLR) waves-known in ultrasonics as "squirting" waves-and points out that their distinctive properties make them well-suited for carrying positive feedback between rows of outer hair cells. This could result in standing-wave resonance-in essence a narrow-band cochlear amplifier. Based on known physical properties of the cochlea, such an amplifier can be readily tuned to match the full 10-octave range of human hearing. SLR waves propagate in a thin liquid layer enclosed between two thin compliant plates or a single such plate and a rigid wall, conditions found in the subtectorial space of the cochlea, and rely on the mass of the inter-plate fluid interacting with the stiffness of the plates to provide low phase velocity and high dispersion. The first property means SLR wavelengths can be as short as the distance between rows of outer hair cells, allowing standing wave formation; the second permits wide-range tuning using only an order-of-magnitude variation in cochlear physical properties, most importantly the inter-row spacing. Viscous drag at the two surfaces potentially limits SLR wave propagation at low frequencies, but this can perhaps be overcome by invoking hydrophobic effects.

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Sensors, motors, and tuning in the cochlea: interacting cells could form a surface acoustic wave resonator

Bell

2006

Bioinspir. Biomim.

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The outer hair cells of the cochlea occur in three distinct and geometrically precise rows and, unusually, display both sensing and motor properties. As well as sensing sound, outer hair cells (OHCs) undergo cycle-by-cycle length changes in response to stimulation. OHCs are central to the way in which the cochlea processes and amplifies sounds, but how they do so is presently unknown. In explanation, this paper proposes that outer hair cells act like a single-port surface acoustic wave (SAW) resonator in which the interdigital electrodes--the three distinctive rows--exhibit the required electromechanical and mechanoelectrical properties. Thus, frequency analysis in the cochlea might occur through sympathetic resonance of a bank of interacting cells whose microscopic separation largely determines the resonance frequency. In this way, the cochlea could be tuned from 20 Hz at the apex, where the spacing is largest, to 20 kHz at the base, where it is smallest. A suitable candidate for a wave that could mediate such a short-wavelength interaction--a 'squirting wave' known in ultrasonics--has recently been described. Such a SAW resonator could thereby underlie the 'cochlear amplifier'--the device whose action is evident to auditory science but whose identity has not yet been established.

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Measurement of Basilar Membrane Vibration Using a Scanning Laser Interferometer

Cited by 3 publications

References 0 publications

Evidence of tectorial membrane radial motion in a propagating mode of a complex cochlear model

Evidence of tectorial membrane radial motion in a propagating mode of a complex cochlear model

The cochlear amplifier as a standing wave: “Squirting” waves between rows of outer hair cells?

Sensors, motors, and tuning in the cochlea: interacting cells could form a surface acoustic wave resonator

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