Physicians might say it's none too soon. The health effects of inescapable noise have long been known to the medical profession. The most obvious effect is hearing loss. According to the National Institute for Occupational Safety and Health, a federal agency that investigates workplace hazards, more Americans suffer from work-related hearing loss than from any other occupational impairment. In addition, the National Campaign for Hearing Health, a public-service effort sponsored by the Deafness Research Foundation, reported in August 2000 that one-third of all cases of hearing loss in the United States are caused by noise in the workplace.

But noise doesn't have to be ear-shattering to be harmful. Any unwanted sound that continues indefinitely and is beyond a person's control can have effects on health. The U.S. Environmental Protection Agency has reported that constant noise may contribute to high blood pressure and heart disease. Noise can also hamper the immune system's ability to fight infection and disease, and it can cause psychological problems such as fatigue and irritability.

These reactions to noise are a biological inheritance from our prehistoric ancestors. To survive, early humans had to respond quickly to threats in the environment, such as dangerous animals. Often, the first warning of such a threat was the sound it made. For example, a person who heard the roar of a dangerous animal had to be instantly ready to engage in a fight to the death or run for safety. To spur this “fight or flight” response, the human body evolved to suddenly produce large amounts of adrenalin, a substance that increases heart rate and elevates blood pressure to provide muscles with additional oxygen. In our modern society, noises are usually more annoying than threatening, but our physical responses have not changed.

Because noise can be stressful—or at the very least, distracting—reducing noise has long been important in places such as libraries and art museums. But the quest for quiet is spreading, in part because people put a value on peaceful surroundings. For example, houses located close to busy highways are usually worth substantially less than ones in quiet neighborhoods. Prospective buyers are usually willing to pay more to avoid being subjected to the constant drone of traffic.

(Source: How stuff works?)