[Cochlear physiology and physiopathology. Recent data].

Our concept of cochlear physiology has changed so drastically over the last decade that most classical textbooks have become obsolete. This bibliographical inadequacy regarding the functioning of the normal cochlea is particularly disturbing when it comes to addressing patho-physiology problems (hearing loss or tinnitus). What drastic changes have there been, that can justify such need for information updating? These relate primarily to the role of one the two types of sensory cells of the cochlea; i.e., the outer hair cells (or OHC). These cells are endowed with contractile properties and react to tonal impulse by modifying the vibration of the cochlear partition. This "active mechanism" response provokes a localized amplification of the vibration imparting to these classical sensory transducers, or inner hair cells (IHC), their optimal frequency sensitivity and discrimination properties. This new concept alone would suffice to justify our present topic. We chose, however, to insert a general presentation of cochlear physiology, the intent of which is to briefly review the classical data and to analyze in some depth the issues that have drastically changed our knowledge.