Transient-evoked stimulus-frequency and distortion-product otoacoustic emissions in normal and impaired ears.
Transient-evoked stimulus-frequency otoacoustic emissions (SFOAEs), recorded using a nonlinear differential technique, and distortion-product otoacoustic emissions (DPOAEs) were measured in 17 normal-hearing and 10 hearing-impaired subjects using pairs of tone pips (pp), gated tones (gg), and for DPOAEs, continuous and gated tones (cg). Temporal envelopes of stimulus and OAE waveforms were obtained by narrow-band filtering at the stimulus or DP frequency. Mean SFOAE latencies in normal ears at 2.7 and 4.0 kHz decreased with increasing stimulus level and were larger at 4.0 kHz than latencies in impaired ears. Equivalent auditory filter bandwidths were calculated as a function of stimulus level from SFOAE latencies by assuming that cochlear transmission is minimum phase. DPOAE latencies varied less with level than SFOAE latencies. The ppDPOAEs often had two (or more) peaks separated in time with latencies consistent with model predictions for distortion and reflection components. Changes in ppDPOAE latency with level were sometimes explained by a shift in relative amplitudes of distortion and reflection components. The pp SFOAE SPL within the main spectral lobe of the pip stimulus was higher for normal ears in the higher-frequency half of the pip than the lower-frequency half, which is likely an effect of basilar membrane two-tone suppression.
Konrad-Martin
Dawn
D
VA RR&D National Center For Rehabilitative Auditory Research, Portland VA Medical Center, Portland, Oregon 97239, USA. dawn.martin@med.va.gov
Keefe
Douglas H
DH
D000293:Adolescent; D000328:Adult; D001309:Auditory Threshold / Q000502:physiology; D005260:Female; D006311:Hearing Disorders / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008144:Loudness Perception / Q000502:physiology; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D010897:Pitch Discrimination / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012016:Reference Values; D013018:Sound Spectrography