In order to contribute to knowledge of the elementary auditory functions in infancy, a group of normally hearing children below the age of four years was examined using advanced tests for cochlear (remote masking, brief-tone audiometry, critical ratio) and central auditory functions (masking-level difference). The results showed that both cochlear and central auditory functions were almost the same in three-year-olds as they were in adults, if not better. This behavior is similar to that recorded with electrophysiological methods and leads to the conclusion that at age three years the auditory system has completed its neurofunctional maturation and it is therefore completely efficient in its elementary psychosensorial functions.