Electrical Recording of Otoacoustic Emission.

概要

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Many lines of evidence support the hypothesis that spontaneous otoacoustic emissions (SOAE) are produced by spontaneous mechanical oscillation within the cochlea, and perhaps motile properties of the outer hair cells. If this is the case, SOAE, emitted acoustically in the external auditory meatus, could also be recorded electrically as cochlear AC-potential. In the present study, SOAE were recorded both acoustically and electrically in the guinea pigs to examine the correlation between electrically recorded SOAE (ER-SOAE) and acoustically recorded SOAE (AR-SOAE).1) In 4 out of 20 guinea pigs (20%), SOAE could be detected both acoustically and electrically.2) Electrical signals of SOAE had a better S/N ratio than acoustical signals. Generally, only some ER-SOAE could be detected acoustically.3) Almost without exception, the prominent frequencies (PF) of multiple ER-SOAE correspond to the intermodulation distortion product, or harmonics.4) ER-SOAE were suppressed by asphyxia or intense sound exposure and reappeared upon re-breathing or discontinuation of the external tone. During recovery PF showed a transient downward shift in frequency.5) SOAE were synchronized in phase with the external tone in the spectral neighborhood of SOAE. The averaged waveform of SOAE synchronized with the external tone was the same with either acoustic or electrical signals.