The auditory brainstem electric response yields information on both the neurological and the audiological status of infants and adults. These early waves have particular properties as: non-habituation, absence of latency modifications between sleep, awake state, or under high doses of barbiturates. We have developed a procedure for extracting each type of information by measuring the latencies of wave I (auditory nerve) and wave V (inferior colliculus), then the speed of conduction between these two waves.