Cortical Auditory Evoked Potential (CAEP) and the chirp Auditory Steady State Response (ASSR) in predicting behavioural hearing thresholds in adults with sensorineural hearing loss

Abstract

Abstract

Purpose: To compare the frequency specific Cortical Auditory Evoked Potential (CAEP) and the chirp-evoked 40 Hz Auditory Steady State Response (ASSR) with equivalent residual noise levels for behavioural threshold prediction in adults with normal hearing and with SNHL.

Method: The study tested 23 adults with normal hearing and 20 adults with SNHL. The participants were aged between 18–65 years. A repeated measures within- participant descriptive design was used to collect the quantitative data. The participants underwent behavioural pure tone, CAEP and ASSR testing on the same day.

Results: Similar CAEP difference scores across frequencies for the participants with normal hearing (mean=12.32-14.40 dB) and with SNHL (mean=10.00-16.47 dB) were measured. However, for the ASSR difference scores across frequencies slightly smaller difference scores were measured for the participants with SNHL (mean=10.17-17.30 dB) than for the participants with normal hearing (mean=11.74- 17.14 dB). CAEP thresholds were significantly closer to the behavioural pure tone thresholds at 500 (p=0.028; mean absolute difference 14.40 dB) and 2000 (p=0.016; mean absolute difference 12.56 dB) Hz for participants with normal hearing. In participants with sensorineural hearing loss, CAEP and ASSR thresholds were measured at similar sensation levels and were not statistically different (p>0.05).

Conclusion: For the purpose of threshold estimation, representing the auditory function to the level of the auditory cortex the CAEP was closer to the behavioural hearing thresholds than the 40 Hz ASSR at all frequencies except at 4000 Hz, regardless of the hearing sensitivity.

Keywords: Auditory steady state response (ASSR), Cortical auditory evoked potential (CAEP), Auditory evoked potential (AEP), Residual noise, Signal to noise ratio (SNR), objective threshold estimation, awake adults.