Slide show: How you hear

The inner ear contains a group of interconnected, fluid-filled chambers. The snail-shaped chamber, called the cochlea (KOK-lee-uh), plays a role in hearing. Sound vibrations from the bones of the middle ear are transferred to the fluids of the cochlea. Tiny sensors (hair cells) lining the cochlea convert the vibrations into electrical impulses that are transmitted along the auditory nerve to your brain. This is where the initial damage and hearing loss occur due to age, noise exposure or medication.

The other fluid-filled chambers of the inner ear include three tubes called the semicircular canals (vestibular labyrinth). Hair cells in the semicircular canals detect the motion of the fluid when you move in any direction. They convert the motion into electrical signals that are transmitted along the vestibular nerve to the brain. This sensory information enables you to maintain your sense of balance.