[Evaluation of hearing thresholds of 40Hz auditory event related potential and auditory brainstem response].
Recordings of pure tone response, 40 Hz auditory event-related potential (40 Hz AERP) and auditory brainstem response (ABR) were obtained for 74 ears of 42 cases (32 normal ears, 42 injured ears). 40 Hz AERP (0.5-2 kHz) of 20 ears was tested under natural sleep and awake conditions. The results showed that the threshold of 40 Hz AERP was higher than that of tone pip, with the difference of 12.7 +/- 6.4 dBnHL at 0.5 kHz, 14.7 +/- 6.3 dBnHL at 1 kHz, and 15.6 +/- 5.6 dBnHL at 2 kHz respectively. The threshold of 40 Hz 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.