RESUMO
Objective To compare the characteristics between two kinds of 40Hz auditory evoked potentials and provide suitable index for clinical auditory test of low-frequency. Methods The potentials including 40Hz auditory event related potential of middle latency response(40Hz AERP-MLR) and 40Hz auditory event related potential of early latency response(40Hz AERP-ELR) from window and vertex were recorded in guinea pigs. Results The common characteristics of the potentials were good frequency response,easy identification and lower responsive thresholds.Amplitude of 40Hz AERP-ELR was higher and threshold was lower than 40Hz AERP-MLR,especially 0.5kHz tone burst,which was (14.15?6.06)dBnHL.In vertex,the threshold of 40Hz AERP-MLR was (43.50?9.65)dBnHL,which was higher than that in round window(P