Simultaneous recording of early and middle components of auditory electric response

The auditory brain stem response (ABR) and the auditory middle response (AMR) were simultaneously recorded in 19 normal adults and 29 patients with hearing loss. The test was performed using tone pips at 0.5, 1, 2, and 4 kHz with intensity levels of 0, 10, 20, and 30 dB above the individual's behavioral threshold. A wide pass-band of 0.5 Hz to 3 kHz was used for recording the response. The typical waveform of the response provided six peaks that were successively labeled as P10, N15, P20, N25, P35, and N45. P10 was a large positive deflection in the ABR. N15-P20-N25, P35, and N45 corresponded to the Na peak complex, Pa, and Nb of the AMR, respectively. Of all components recorded, P10 was detected most consistently. However, because N25 and P35 of the AMR also gave important information for the assessment of hearing, simultaneous recording of the ABR and AMR is considered a useful clinical technique for estimating hearing in normal as well as in hearing-impaired subjects.