Date of Graduation

Spring 2022

Degree

Doctor of Audiology

Department

Communication Sciences and Disorders

Committee Chair

Abdullah Jamos

Abstract

Noise exposure has been known to cause both temporary and permanent shifts in hearing thresholds in humans. Animal and human studies have shown noise exposure to lead to damage to the ribbon synapses of the cochlea. This damage, referred to as noise induced hidden hearing loss (NIHHL), is not detectable with standard hearing assessments, though can be the cause of difficulties understanding speech in the presence of background noise. Recent studies have begun to explore the use of electrocochleography (ECochG) to detect this neural damage in humans. Such studies strive to aid in the development of a clinical tool for the diagnosis of NIHHL in humans. To investigate the effects of stimulus intensity and presentation rate on ECochG responses, male and female participants were recruited and separated into high and low noise exposure groups based off noise exposure questionnaires. Individuals then underwent audiometric testing, speech-in-noise testing, and ECochG testing. All participants had hearing thresholds within normal limits. Speech testing was not found to be clinically significantly different between groups. While both the stimulus rate and intensity significantly affected the AP amplitude, there was only a borderline significant difference between effects of the stimulus intensity on the AP amplitude of the low-risk group as compared to the high-risk group. These results agree with previous human studies and indicate ECochG may be a potential diagnostic tool for NIHHL. No significant difference in SP amplitude was seen between groups with changes in stimulus intensity or rate was seen between groups. Stimulus intensity did, however, have an effect on SP amplitude. While ECochG shows promise as a potential diagnostic tool for NIHHL, further research is necessary both to confirm the usefulness of the measure and to develop a clinical diagnostic protocol.

Keywords

noise induced hidden hearing loss, electrocochleography, noise exposure, cochlear synaptopathy, ribbon synapse, electrophysiology, hearing loss

Subject Categories

Speech and Hearing Science | Speech Pathology and Audiology

Copyright

© Amanda E. McCarthy

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