High-frequency hearing impairment assessed with cochlear microphonics

Abstract

Conclusion: 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.

Keywords::

• Ear canal electrodes
• cochlear microphonic waveforms
• CMW
• otoacoustic emission
• OAE
• electrocochleography
• ECoG
• ECochG
• cochlear function
• auditory brainstem response
• ABR
• acoustic noise
• auditory neuropathy

Acknowledgments

Portions of this work were supported by grants from the Canada Foundation for Innovation (M.Z.), Glenrose Rehabilitation Hospital Foundation (M.Z.), and research funding from the University of Alberta (M.Z.). The author wishes to thank the subjects who participated in the experiment for their time and effort; Jane De Pauw for effective editing and proofreading; Pinky Raju, Amanda Lopez, Logan Horner, Jamie King, and Ann Varghese for participation in the study; Dr Vicky Zhao, Mr Brian Schmidt, and Melanie Campbell for insightful discussions of the manuscript; and anonymous reviewers for their very valuable comments.

Declaration of interest: The author reports no conflicts of interest. The author alone is responsible for the content and writing of the paper.