Sound is made up of vibrations that strike the eardrum to make it move. The eardrum then makes the middle ear bones move, sending energy into the cochlea of the inner ear. There are tiny cells within the cochlea called hair cells because of the hair-like structures (called hair bundles) on top of them. Each ear has 18,000 hair cells, which are so tiny they could all fit on the head of the pin. Sounds move the hair bundles, which changes the movement into electrical energy, stimulating the auditory nerve. The signal travels up the nerve to the brain, which recognizes the sound. These hair cells are critical to hearing. Too much sound results in too much movement, which pushes the hair cells over, and loud, prolonged noise can cause the hair cells to break off. When many hair cells are damaged, the whole cell dies, leading to hearing loss.
Imagine that hair cells are a patch of grass. When you walk lightly and infrequently across that patch of grass, the grass bends but recovers to stand up straight again. But if you march heavily and frequently across the grass – or you drive a heavy vehicle over it – not all the grass will be able to withstand the trauma, and many blades will be broken. Just as the vehicle can irrevocably damage the blades of grass, loud sounds can similarly damage the hair cells within the ear. The death of the cell is permanent, as no hair cells will grow back to replace the broken ones. When you lose enough of those cells, you’ll wind up with permanent hearing loss.
Therefore, it’s critical to protect the hair cells so they’ll last for a lifetime. Even if you have some hearing loss, protect your ears so you don’t lose even more hair cells and, subsequently, more hearing.
Tinnitus: hearing ringing or whistling sounds
Have you ever been to a loud rock concert, standing close to the stage, and then had ringing in your ears for several hours afterwards? That’s called tinnitus, and some people experience this condition before they even notice a hearing loss. While many people experience a ringing sensation associated with tinnitus, some people hear other sounds – including hissing, roaring, whistling, chirping or clicking. In fact, 40 to 50 million Americans have tinnitus, and for 25% of those people, the condition is so severe or long-lasting that they need medical help.