The Vibratory Pattern of the Round Window in Cats
作者:
Shyam M. Khanna,
Juergen Tonndorf,
期刊:
The Journal of the Acoustical Society of America
(AIP Available online 1971)
卷期:
Volume 50,
issue 6B
页码: 1475-1483
ISSN:0001-4966
年代: 1971
DOI:10.1121/1.1912801
出版商: Acoustical Society of America
数据来源: AIP
摘要:
Round‐window displacements were recorded by means of time‐averaged holography in live cats and in fresh animal cadaver specimens. Considerable technical difficulties had to be overcome first, before such recordings became feasible. In the majority of cases, the displacement pattern was complex, even at low frequencies, with the maximum displacement occurring in the anterio‐superior region. Between‐animal variations were relatively large. From the reconstructions, volume displacements and eventually volume velocities were calculated for given frequencies. Since the sound pressures had been directly applied to the stapes footplate, the volume velocities for given sound‐pressure levels (SPLs) could be converted into inner‐ear impedance values, the assumption being that, for a given situation, volume displacements of the round window should equal those of the oval window. Inner‐ear impedances were in the low megohm range; in this respect the results confirm those of an earlier study from this laboratory. However, while in cadaver specimens the results were reasonably uniform, in live animals impedance appeared to increase with exposure to high SPLs. This increase in impedance appears to exert a protective function for the inner ear. Experiments to explore this latter function in more detail are being planned.
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