The four levels of noise are slight noise, moderate noise, severe noise and extreme noise.
1, minor noise
Minor noise refers to the sound of small, short, intermittent noise, such as minor car horns, short firecrackers, etc.. This kind of noise generally does not affect people's lives too much.
2. Medium noise
Medium noise refers to noise that lasts for a longer time and is louder, such as the noise of transportation and the sound of machinery in construction sites. This kind of noise may disturb people's normal life and work, but usually does not cause much harm to health.
3. Serious noise
Serious noise refers to noise that is loud, lasts a long time and is close by, such as the sound of airplanes taking off and landing at airports and large-scale concerts. This kind of noise not only interferes with people's normal life and work, but also may cause health problems.
4, extreme noise
Extreme noise refers to the sound is very big, the duration is very long, the distance is very close to the noise, for example, the sound of explosions, large-scale machine roar and so on. This kind of noise can cause great harm to people.
Sources of noise
1, transportation: transportation is one of the most important sources of noise in the city, including cars, buses, trains, airplanes and so on. The engines of these vehicles, the friction between the tires and the ground, and the brakes all produce noise.
2, construction sites: construction sites are another important source of noise. Pile drivers, excavators, concrete mixers and other construction machinery will produce high noise during use.
3, industrial production: industrial production process, the operation of various mechanical equipment will produce noise, such as machine tools, pumps, fans and so on. These noises will affect the health of workers and surrounding residents.
4, social activities: social activities will also produce noise, such as square dancing, concerts, rallies and so on. These noises will have an impact on the life and rest of the surrounding residents.