Noise pollution is not a necessary price to pay for living in an industrial society. Much

can be done to reduce the severity of the problem. For example, vehicles and other machines can be built to produce less noise. Four-cycle engines can replace much noisier two-cycle engines in such products as lawnmowers, motorboats, and jet skis. Labels that indicate the noise levels of appliances and tools can help consumers avoid noisy products and choose quieter alternatives.

Even after noise is generated, steps can be taken to reduce human exposure to it. At homes or in offices, insulation of walls and double-glazing of windows can decrease sound from traffic, neighbors, and other sources from the outside world. Sound walls along highways can shield nearby neighborhoods from traffic noise. Individuals should protect themselves with earplugs or ear protectors, particularly when noise levels exceed 85 decibels (分贝).

In the industrialized nations, governments have laws and policies to counter noise pollution. In the United States, at least six federal agencies are involved in controlling noise pollution. Since 1969 the Federal Aviation Administration (FAA) has monitored and controlled noise from airplanes, The agency requires that new aircraft meet specified noise standards and that old ones be retrofitted (翻新) or retired. Local airport authorities, with FAA approval, reduce the impacts of noise pollution by routing flights over water or unpopulated areas on takeoff and landing, and by limiting traffic at night. The FAA also encourages airports and local governments to take steps on the ground, such as constructing sound barriers, insulating buildings, and restricting residential development in noisy areas. In extreme eases, airports have relocated people living under flight paths.

In the last 30 years, the United States and other countries have expended considerable efforts to control noise pollution. Most vehicles and many other noise producers are quieter than they used to be. On the other hand, there are more noise-making machines than ever, operating mare of the time. In the United States, most of the roles governing noise pollution were established at least two decades ago, and critics are calling for new, stronger measures, as well as for better enforcement of the old ones. What is true of most other kinds of pollution is also true of noise: Our best efforts against it tend merely to keep matters from getting dramatically worse.

The first paragraph tries to tell us how to control noise pollution by ______.

A．taking measures to reduce human exposure to noise

B．using or replacing with quieter products

C．appealing to Government to set up laws

D．people's serf consciousness