Background:
Various auditory evoked potential techniques have been explored as a means of objectively predicting the behavioral audiogram in groups of subjects who cannot provide reliable or accurate behavioral results. The tone-evoked auditory brainstem response (ABR) cannot differentiate between severe and profound SNHL, whereas the auditory steady state response (ASSR) can provide threshold information in a frequency-specific manner at intensity levels of 120 dBSPL. The cortical auditory evoked potential (N1P2 CAEP) has shown advantages over the ABR and ASSR.

Objectives:
To assess the ability of the N1P2 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 into 6 groups according to the degree of hearing obtained by pure tone audiometry (PTA). Hearing threshold was then measured using N1P2 CAEP and ASSR.

Results:
N1P2 CAEP and ASSR were highly correlated to PTA at all frequencies. However, N1P2 CAEP predicted behavioral thresholds more accurately than ASSR at all frequencies, especially at 500 and 1000 Hz in the normal hearing group and for all degrees of SNHL. N1P2 CAEP was equally accurate at all frequencies and predicted behavioral thresholds better at more severe degrees of SNHL at 1, 2, and 4 kHz.

Conclusions:
The N1P2 CAEP can be reliably used as an objective method for estimating the behavioral hearing threshold, yielding more accurate results than the ASSR, especially at lower frequencies and with more severe degrees of hearing loss. We therefore recommend using the N1P2 CAEP in estimating the behavioral threshold in difficult-to-test adults.