High-frequency hearing impairment assessed with cochlear microphonics.
CONCLUSIONS
Cochlear microphonic (CM) measurements may potentially become a supplementary approach to otoacoustic emission (OAE) measurements for assessing low-frequency cochlear functions in the clinic.


OBJECTIVE
The objective of this study was to investigate the measurement of CMs in subjects with high-frequency hearing loss. Currently, CMs can be measured using electrocochleography (ECochG or ECoG) techniques. Both CMs and OAEs are cochlear responses, while auditory brainstem responses (ABRs) are not. However, there are inherent limitations associated with OAE measurements such as acoustic noise, which can conceal low-frequency OAEs measured in the clinic. However, CM measurements may not have these limitations.


METHODS
CMs were measured in human subjects using an ear canal electrode. The CMs were compared between the high-frequency hearing loss group and the normal-hearing control group. Distortion product OAEs (DPOAEs) and audiogram were also measured.


RESULTS
The DPOAE and audiogram measurements indicate that the subjects were correctly selected for the two groups. Low-frequency CM waveforms (CMWs) can be measured using ear canal electrodes in high-frequency hearing loss subjects. The difference in amplitudes of CMWs between the high-frequency hearing loss group and the normal-hearing group is insignificant at low frequencies but significant at high frequencies.
Departments of Speech Pathology & Audiology and Surgery-Otolaryngology, University of Alberta and Glenrose Rehabilitation Hospital, Edmonton, Alberta, Canada. ming.zhang@ualberta.ca
Ming
M
Zhang
D000161:Acoustic Stimulation; D000328:Adult; D001300:Audiometry, Evoked Response; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold / Q000502:physiology; D001933:Brain Stem / Q000503:physiopathology; D003055:Cochlear Microphonic Potentials / Q000502:physiology; D004566:Electrodes; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005260:Female; D006316:Hearing Loss, High-Frequency / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D008297:Male; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D012984:Software; D055815:Young Adult