The process of hearing involves sound waves creating mechanical motions that cause fluid in the ear to move in waves and trigger nerve impulses that the brain interprets as sound.
The outer ear functions to funnel sound waves. The vibrations from these waves reach the middle ear and move the tympanic membrane, often called the eardrum. This causes three bones, called the auditory ossicles, to also move. The bones make contact with a fluid filled structure in the inner ear called the cochlea. The mechanical movements of the auditory ossicles move fluid inside the cochlea. Fluid waves move hair cells that line the cochlea. The movement of these cells activates nervous system receptors. Signals are carried through the vestibulocochlear nerve, cranial nerve VIII, to the temporal lobe of the brain, where they are interpreted as sound.