In this study the cochlear microphonics were recorded from human subjects and guinea pigs on ECoG, and they were used to evaluate the relationship between two-tone suppression and the suppressor frequency and intensity.
The results are as follows: 1. The amplitude of the ECoG CM suppressed not only at higher frequency but also at lower frequency. At the higher frequency as 1 or 2 octave, CM suppression was usually evident. 2. Two-tone suppression measured with ECoG was observed in human subjects, and it was concluded that the basilar membrane of the human cochlea has the nonlinear characteristics.
The results of this study are consistent with the previous findings which were obtain by the use of CM, by a model of the basilar membrane and by the use of the Mössbauer effect, but some differences between our results. and the two-tone suppresion obtained from the acoustic nerve, cochlear nucleus and psychophysical observations were observed. This difference was thought to be caused by the difference of the intensity of the test and suppressing tones and by the existence of the different 2nd filter.
