Named after the Latin word for snail shell, the cochlea is a coiled, tapered tube inside the mammalian inner ear, responsible for transmitting sound to the auditory nerve. Georg von Békésy won the Nobel Prize for Physiology or Medicine in 1961 for his work elucidating the workings of the cochlea.

The cochlea consists of three fluid-filled chambers - scala tympani and scala vestibuli (both of which contain perilymph ), and scala media (which contains endolymph). The stapes transmits vibrations to the fenestra ovalis (oval window) on the outside of the cochlea, which vibrates the perilymph in scala vestibuli. This in turn vibrates the endolymph in scala media, which causes movement of the basilar membrane between scala media and scala tympani. When the basilar membrane moves, it stimulates hair cells in the organ of Corti, which are connected to the auditory nerve via cochlea nerve fibres. The auditory nerve transmits sound data to the brain as electrical impulses.

See also: Cochlear implant