[The mechanisms of hearing and hearing loss].

The ear is constituted of an apparatus for transmission, the external ear and the middle ear, and of an apparatus for perception, the inner ear or cochlea and the acoustic nerves. A disorder can occur at each of these levels, leading to different types of hearing loss: defective transmission through a disorder of the external canal and/or by disorder of the tympanic-middle ear bone apparatus; endocochlear hearing loss through disorder of the ciliary cells of the Corti ganglion and/or by metabolic disorder or by pressure modification (such as Meniere's disease) of the endolymph compartment of the inner ear; retrocochlear hearing loss through disorders of the 8th nerve; central hearing loss through disorder of the temporal cortex.