Abstract: Recordings of pure tone response, 40Hz auditory event－ related potential (40Hz AERP) and auditory brainstem response (ABR) were obtained for 74 ears of 42 cases (32 normal ears, 42 injured ears). 40Hz AERP(0.5～ 2kHz) of 20 ears was tested under natural sleep and awake conditions. The results showed that the threshold of 40Hz AERP was higher than that of tone pip, with the difference of 12.7± 6.4dBnHL at 0.5kHz, 14.7± 6.3dBnHL at 1kHz, and 15.6± 5.6dBnHL at 2kHz respectively. The threshold of 40Hz AERP increased in natural sleep compared with that in awake state. The threshold of ABR was higher than the behavioral. The data suggests that jointly using several tests get more accurate and objective results in evaluating hearing loss.

Key words: 40Hz auditory event－ related potential, auditory brainstem response, hearing loss