Effect of High Pass Filtered Masking Noise on SP in Man

Effects of high pass filtered masking noise on the amplitude and sign of SP were studied using the E Coch. G technique. SP and AP were recorded from eight subjects with normal hearing by means of the transtympanic electrodes using 2kHz-8kHz tone bursts as acoustic stimuli. The following results were obtained. 1) The effect of masking on the SP amplitude was less significant for the decrease in amplitude than that on the AP amplitude. 2) As the cut-off frequency of high pass filtered masking noise was approximated to the frequency of tone burst stimulus, SP amplitude became remarkably decreased. 3) The change in sign of SP was not observed using the high pass filtered masking noise. It is concluded that the SP recorded by the transtympanic technique in human is specific to the frequency of tone bursts with higher stimulus frequency than 2kHz. Furthermore the SP in man seems to have different characteristici from the AVE-SP in animals.