Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of E.N.T

Background: Various auditory evoked potential techniques have been used as means of objective estimation of the behavioural audiogram in subjects who cannot provide reliable or accurate behavioural results. Objectives: To assess the ability of the N1-P2 cortical auditory evoked potential (CAEP) to estimate the hearing threshold level at different frequencies, in normal hearing adults and adults with different degrees of sensorineural hearing loss (SNHL); and to compare it to the auditory steady state response (ASSR). Methods: This study included 90 subjects (180 ears), grouped according to the degree of hearing obtained by pure tone audiometry (PTA), into 6 groups. Hearing threshold was then measured with using N1P2 and ASSR. Results:N1P2 and ASSR were highly correlated to PTA at all frequencies. However, CAEP predicted the behavioral thresholds more accurately than ASSR at all frequencies especially at 500& 1000Hz in the normal hearing group and in in all degrees of SNHL. N1P2 was equally accurate in all frequencies and predicted the behavioral thresholds better at more severe degrees of SNHL at 1, 2 &4 kHz. ASSR was closer to PTA at 2000Hz than other frequencies in all groups. Conclusion: BothN1P2 CAEP and the ASSR can be reliably used as objective methods in estimating the behavioral hearing thresholds, with the N1P2 yielding more accurate results than the ASSR especially at lower frequencies and at more severe degrees of hearing loss. So, we recommend using these tests, and preferably the N1P2, in estimating the behavioral threshold in difficult to test adults

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