cochlea

Your inner ear contains roughly 15,500 hair cells — each one tuned to a specific frequency — and they do not grow back. Lose them to noise, age, or disease, and the corresponding frequencies are gone permanently. Here is how they work, and why that loss is irreversible in mammals.

How the ear turns air pressure waves into the experience of sound — outer, middle, and inner ear anatomy, cochlear mechanics, and hearing loss.