The cochlea is the auditory center of the inner ear, a fluid-filled organ that translates the vibrations of auditory sound into impulses that the brain can understand.
The walls of cochlea are made of bone with a thin lining of tissue encompassing three chambers. The two large chambers include the upper vestibular canal and lower tympanic canal, which both contain fluid called perilymph. The two canals are separated by a smaller chamber called the cochlear duct, which is lined with the basilar membrane and filled with fluid called endolymph. In biology, the prefix peri- means around, and the prefix endo- means within. At the floor of the cochlear duct is the organ of Corti, which is lined with hair cells that act as receptors. Just above the organ of Corti is the tectorial membrane.