Treating the spontaneous electrical activity (SEA) and the evoked potential due to a p pulse at the MES auditory cortex as random variables at 3-msec. epochs, an increase in standard deviation during the evoked potential was found suggesting the occurrence of two statistical processes. By suitable application of cocaine hydrochloride locally to the cortex, it was possible to suppress the standard deviation of SEA and obtain a potential with no or little variance. This potential was defined as the ‘afferent response’ representing the activity due to volleys from the ear. It was concluded that the locally arising SEA has connections to the nerve elements causing the afferent response, thus producing the variance of the evoked potential. The SEA, therefore, is an information destroying process, since it reduces the detectability of response from stimulation of the ear.