Abstract: The present invention relates to a method for monitoring the brain's sub-cognitive activity through otoacoustic emissions. More specifically, the present invention deals with a method and device for monitoring the brain's functions that are manifested by sub-cognitive activities. The sub cognitive activities are monitored by matching to the spectrograms of a standard evoked oto-acoustic emissions signals to monitor mismatches as indicators of normal or malfunctioning sub cognitive neurological functions. The invention relates also to a device for monitoring the brain's sub-cognitive activity through otoacoustic emissions. More specifically, the present invention deals with a method and device for monitoring the brain's functions that are manifested by sub-cognitive activities. The sub cognitive activities are monitored by matching to the spectrograms of a standard evoked oto-acoustic emissions signals to monitor mismatches as indicators of normal or malfunctioning sub cognitive neurological functions.