Middle and Inner Ear
Sound waves travel through the ear canal to the eardrum, a thin membrane that separates the middle ear from the external ear, causing the eardrum to vibrate. These vibrations set in motion a chain of three tiny bones in the middle ear, respectively known as the hammer (malleus), anvil (incus), and stirrup (stapes). The vibrations from these bones are transmitted to the cochlea, a hollow tube in the inner ear coiled in the shape of a snail’s shell. This motion stimulates hair cells within the cochlea, which in turn produce nerve impulses that travel up the auditory nerve, ultimately to the brain.