Keywords: cochlear transduciton, cochlear discrimination, cochlear amplification, otoacustic emissions, cochlear physiology, hair cells, electromotility

Abstract: This paper describes the inner cochlear structure. The passive mechanism of progressive waves is revised A structural and physiological description is done with emphasis in differences of outer and inner hair cells systems, and the capacity of contraction of the outer hair cells as well the codification of the sound message of inner hair cells. The importance of afferent and efferent innervation of outer and inner hair cells are stressed specially their actions in the electrical biomechanical process of the outer hair cells. The importance of this process is to increase the capacity of cochlear amplification. It is emphatized the outer and inner hair cells stimulation. Finally, the three steps of the cochlear transduciton, are describe.