[Use of acoustic distortion products in clinical diagnosis. The site of origin of otoacoustic emissions in the inner ear].
Distorsion product otoacoustic emissions (DPOAE) are generated by a continuous bitonal stimulation of the cochlea. The resulting emissions are measurable in a definite mathematical function of the primaries (mf1 +/- nf2; f1 < f2). In humans sound emission at the frequency 2f1-f are usually detectable. To determine if a disturbance of DPOAE-amplitude is associated with a cochlear lesion in the frequency region of the evoked emissions or the primaries, we performed suppression experiments using normal-hearing, healthy probands (n = 14). DPOAE were measured in the frequency range between 800 Hz and 8 kHz with different sound-pressure levels for the primaries. Evoked emissions for each proband were measured with these different stimulus parameters to determine baseline values. In suppression experiments sound emissions were evoked continuously with different stimuli between 800 Hz and 8 kHz, disturbed simultaneously with a third tone of 1, 2 and 4 kHz and then compared with baselines. Suppressor tones (1, 2, 4 kHz) reduced significantly the DPOAE amplitudes in the frequency region of the geometric mean of the primaries. This indicates that a reduction of the emission amplitude in associated with a cochlear lesion near the generation site of the DPOAE. The suppression curves exhibit a sharp and steep graph, indicating their relation to cochlear frequency selectivity.
Universitäts-HNO-Klinik Tübingen.
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Plinkert
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Harris
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Probst
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D003051:Cochlea / Q000502:physiology*; D005260:Female; D006801:Humans; D008144:Loudness Perception / Q000502:physiology*; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D010469:Perceptual Distortion / Q000502:physiology*; D010898:Pitch Perception / Q000502:physiology*; D011571:Psychoacoustics; D012016:Reference Values; D013018:Sound Spectrography