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The booming of America has many causes. Population growth in city centers, loss of rural land to suburban sprawl, and the soaring number and size of cars on the highways all play a role. So too does the entertainment industry, with Walkmans, iPods and surround-sound theaters pouring noise into consumers' ears. Even sports stadiums, always noisy places, have got louder as earsplitting commercials fill the comparatively quiet interludes that used to prevail during pauses in the action. Also to blame are moves made in Washington more than a generation ago. In 1972, the Office of Noise Abatement and Control (ONAC) was created to identify sources of noise and combat them. But in 1981, Congress and the Reagan Administration eliminated ONAC funding, removing one federal blanket that had been thrown over the din.
Whatever the roots of the problem, the clamor is now everywhere--and the workplace may be the worst place of all. At least 20% of U.S. workers do their jobs in environments that could endanger their hearing, according to NIOSH. The U.S. government estimates that more than 90% of coal miners suffer hearing impairment by age 50. Even farms are not exempt: according to the New York Center for Agricultural Medicine and Health, a staggering 75% of farmers now exhibit some hearing impairment, mostly as a result of noisy equipment. "Hearing loss is one of the most common workplace conditions," says audiologist Ted Madison, president of the National Hearing Conservation Association.
For kids, the racket starts in the cradle. A squeaky toy held close to the ear--which is precisely where babies may put them--can reach 94 db. A toy xylophone can ring in at 92 db. And since babies' ear canals are so small, a sound that gets in them may knock around harder than it does in an adult's ears and do commensurately more damage. When these battered baby ears make it to high school they only suffer more abuse as kids start listening to music at full volume and going to dance clubs where wall-to-wall reverberation is the point.
Noise can be controlled to an extent, depending on the source. Some of the biggest sources of ambient noise are highways and roads, but the cause is less honking horns or gunning engines--though those play a role--than tires hitting pavement. Pliable rubber making contact with asphalt doesn't seem as if it would produce a lot of noise but in fact it does, and in a lot of ways. As any spot on the tire strikes the highway, it hits with the thunk of a little rubber hammer. Also, the patch of tire that's in contact with the ground at any instant--the so-called tread block--can squeak like a sneaker on a gym floor and pop like a suction cup when it pulls back off the surface. Air pumping through tire grooves makes noise of its own.
The solution, says engineer Bob Bernhard, co-director of Purdue University's Institute for Safe, Quiet and Durable Highways, is to change not the tires but the road surface. "You can make the pavement porous," he says, "which affects the air-pumping mechanism. You can also mix a little rubber in with the asphalt, which changes the road's stiffness." Porous surfaces are already being rolled out in parts of Georgia, Florida and Arizona, as well as in Europe.