Published in:
Open Access
01-03-2008 | Otology
Changes in CMDP and DPOAE during acute increased inner ear pressure in the guinea pig
Authors:
W. L. Valk, H. P. Wit, F. W. J. Albers
Published in:
European Archives of Oto-Rhino-Laryngology
|
Issue 3/2008
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Abstract
During and after an increase of inner ear pressure, induced by injection of artificial perilymph, the 2f
1 − f
2 and f
2 − f
1 distortion products (DPs) in cochlear microphonics (CM) and otoacoustic emissions (OAE) were recorded in the guinea pig. An inner pressure increase of ∼600 Pa gave only small changes in CMDP and DPOAE. Along with a decrease in f
1 amplitude, a small decrease in amplitude of the 2f
1 − f
2 and a small increase in the f
2 − f
1 were measured in CM. This matches a shift from a symmetrical position of the operating point for hair cell transduction, leading to an increase in even-order distortion and a decrease in odd-order distortion. Similar, a decrease in 2f
1 − f
2 DPOAE was expected. This might be the case at the generation sites but this effect was then more than compensated for by a better middle ear transfer, accounting for the increase of 0.4 dB of the 2f
1 − f
2 DPOAE amplitude. In conclusion, changes of overall inner ear fluid pressure have minor effects on cochlear function. This is a relevant finding for further understanding of diseases with changed inner ear fluid volumes, as Ménière’s.