The use of simulation techniques to investigate the effects of conductive hearing loss on the auditory brainstem response

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Date

2018-11-06

Department

Towson University. Department of Audiology, Speech-Language Pathology and Deaf Studies

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Abstract

A click-evoked Auditory Brainstem Response (ABR) was recorded on 28 normal hearing adult participants to determine the effects of different degrees of conductive hearing loss on the response properties of the ABR. Participants were divided at random into two groups: the normal hearing group and the simulated conductive hearing loss group. In the normal hearing group, baseline behavioral pure tone audiometry from 250-8000 Hz and acoustic immittance testing (tympanometry and contralateral acoustic reflex thresholds from 500-2000 Hz) were performed to ensure normal hearing and middle ear function. Then, ABR testing was performed in both right and left ears to click stimuli beginning at 80 dBnHL. Stimulus intensity was decreased in 10 dB increments until a stimulus intensity of 30 dBnHL was reached. At stimulus intensities less than 30 dB nHL, stimulus intensity was decreased in 5 dB increments until the participant's ABR threshold was determined. In the simulated conductive hearing loss group, baseline behavioral pure tone audiometry from 250-8000 Hz and acoustic immittance testing (tympanometry and contralateral acoustic reflex thresholds from 500-2000 Hz) were performed to ensure normal hearing and middle ear function. Then, 5 mm of moleskin was placed in the tubing for the ER3A insert receivers and pure tone air conduction thresholds were re-measured in each ear. For the conductive group, the ABR was recorded using the ER3A insert receivers with moleskin. The ABR was recorded in both right and left ears to click stimuli beginning at 80 dBnHL. Stimulus intensity was decreased in 10 dB increments until a stimulus intensity of 60 dBnHL was reached. At stimulus intensities less than 60 dBnHL, stimulus intensity was decreased in 5 dB increments until the participant's ABR threshold was determined. For both groups, results revealed an increase in the mean absolute latencies of waves I, III, and V as stimulus intensity decreased. In contrast, results showed a decrease in the mean peak-to-peak amplitudes for waves I-I’ and V-V’ as a function of stimulus intensity. Mean interpeak latency values were consistent across stimulus intensities. Mean absolute latency values for all waves were greater for the simulated hearing loss group than the normal hearing group. In contrast, the mean peak-to-peak amplitude values for waves I-I’ and V-V’ were smaller for the simulated hearing loss group than the normal hearing group. These results were compared to previous data collected in the ABR literature on both normal hearing and conductive hearing loss participants. Results for both groups in the current study were in good agreement with the ABR literature as seen in the mean ABR values and the variability represented by standard deviation measurements. The data collected from this study will be used to develop a parametric approach to generating simulated responses for the commercially available Auditory Brainstem Response (ABR) recording simulator, ISAO by Intelligent Hearing Systems. This data will serve as basis for developing functions of response characteristics such as peak latency and amplitude as well as recording parameters like intensity, rate and stimulus characteristics. Further research should be conducted to determine the effects of other stimulus parameters on the ABR. These stimulus parameters include rate, polarity, and frequency.