Physiology of the Developing Auditory System

The auditory system as a whole can only be studied by behavioral tests. When we speak of hearing, we are considering something that leads to a motor response, either an orientation toward the sound source or an answer to it. Hearing involves localization and identification of the sound. Electrophysiological methods can never describe the system completely, since it is impossible to determine with these methods whether a sound was actually heard. Thus, an electrophysiologically normal system is a necessary condition for normal hearing, but it is not a sufficient condition. Depending on the recording site, one can only test the system up to that point. By testing various stations along the auditory pathway, one may obtain time courses of development at all these points. This allows one, for example, to distinguish between maturation at the cochlear level and maturation of the central nervous system.