How the Ear Hears

Sound waves travel down the ear canal and make the eardrum vibrate. The vibration moves through three tiny bones in the middle ear that connect the eardrum to the spiral-shaped cochlea in the inner ear.

Tiny hair cells in the organ of Corti, which resides inside the cochlea, pick up the vibrations and start to move. That triggers electrical signals that get picked up by auditory nerve fibers and carried to the brain.

If hair cells are damaged or destroyed, electrical signals aren't generated, and sound waves can't connect to the brain's auditory processing center -- making it impossible to hear.

Credit: NPR