Signal encoding in cochlear nucleus is one of the most important process in auditory electrophysiologic research, but little works were done in this field in Korea. Authors investigated pure tone and amplitude modulated(AM) tone encoding behavior of dorsal cochlear nucleus(DCN) and posteroventral cochlear nucleus(PVCN) neurons in unanesthetized decerebrate cats, and detected intrinsic oscillations in the responses of pause-build-type-III neurons of DCN and chopper-type-I or I/III neurons of DCN or PVCN. The intrinsic oscillations were observed in the neurons showing band-pass filter functions to AM tone. These intrinsic oscillations' frequency were not correlated to the chopping frequency, had linear correaltions with the modulating frequency. With increasing intensity of stimuli, these intrinsic oscillations' frequency also showed increasing tendency.