How do we Hear?
The ear is made up of three main parts: the fleshy outer ear, the middle ear and the inner ear. Sound waves are funneled by the outer ear through the ear canal to set up vibrations in the eardrum, a thick, tightly stretched membrane. The vibrations are transferred to the three tiny bones of the middle ear: the hammer, anvil and stirrup and through them to the fluid of the shell-shaped part of the inner ear, the cochlea. In the cochlea, hair cells detect the motion in the fluid and translate it into nerve impulses they send via the auditory nerve to the brain, which interprets the impulses. One common form of hearing loss occurs when the hair cells in the cochlea gradually lose sensitivity or are destroyed through exposure to loud noise as they cannot be replaced.