Abstract: Two-tone suppression (2TS) was studied in AC receptor potentials recorded from scale media in the third turn of guinea pig cochlea. Electrode of round window was used to monitor the CAP threshold. Amplitude-intensity functions for AC component were obtained before and after white-noise exposure. Results indicated that the phenomenon of 2TS wasrelated with nonlinearity of cochlea, and suppressed amplitude decreased with diminish of these high-level nonlinearities. The probability that 2TS caused by media ear and homophonic was diminished. A computer controlled sound stimulator and signal recording system was used in the study, in which FFT was also used to calculate the amplitude of receptor potentials.