What is it that makes your ears ring after something loud (like a private iPod concert turned up too high)? The highfalutin’ word for it is “tinnitus.” When your ear is exposed to sounds that are too loud, the hair cells in the inner ear that act as little sound sensors get damaged. In response to the damage, the brain “turns up the volume” as part of a feedback mechanism. That “increased gain” is what you hear as ringing. After a while the ringing goes away, because you get used to it, but the damage has still been done. So, ringing in your ears is a symptom that you’ve damaged your hearing.
I also had really strong tinnitus when I was on quinine after I contracted malaria — not a sign of hearing loss but just a side effect of the drug. It was so bad that my mother had to shout for me to hear her!
When you’re young, you’ve got lots of excess hair cells that compensate for the loss of the damaged ones. But as we get older, and lose hair cells through the natural process of aging, those of us with a lot of damaged hair cells don’t have any to replace those lost as we age. So we don’t notice the effects of those loud rock concerts until many years later. Isn’t that just the way with so many health problems? By age 25, the average carpenter has the hearing of a 50-year old. Wear your ear protection!
Another thing that happens as we age is that we don’t hear high frequencies as well — a factoid that has been made pretty well known by the new trend of young people having cell phones with high-pitched rings that adults can’t hear. I was in the audience once for a pretty neat demonstration of this effect. It was a physics show, with people ranging from 8 to 60 years old. The professor played an extremely high pitched sound that nobody could hear, and asked us to raise our hands when we heard it. He began to lower the frequency. All the kids’ hands shot up pretty quick, but us old farts had to wait until the sound got much lower before raising our hands. I was disturbed to see that my hand was one of the last up (and I’m not that old!).