The cochlea potentials are recorded in anesthetized guinea pigs. The effects of exposure tones and test tones on the recovery process are treated. The cochlear microphonic does not change its magnitude following the exposure to 8 KHz for a period of two minutes, when the exposure tone is kept below 100 dB SPL. The action potential is more vulnerable to overstimulation than cochlear microphonic. The suppression of action potential to low level of test tone is greater than to high level of test tone. A positive summating potential is observed during the recovery period.