Nonsimultaneous masking experiments (foward masking, pulsation threshold), using a 2-tone masker, shows effects similar to 2-tone inhibition in auditory nerve fibers. Backward masking was examined with 5 subjects [human] where the masker contained a 1000 Hz, 40 dB SPL [sound pressure level] masker and a 2nd tone of variable frequency at 70 dB SPL, called the suppressor. The test signal was 1000 Hz. For certain suppressor frequencies, the masker suppressor combinations produced less masking than the 40 dB SPL masker alone.