According to the mechanical characteristics of sound source, noise pollution can be divided into: noise caused by gas disturbance, noise caused by solid vibration, noise caused by liquid impact and electromagnetic noise caused by electromagnetic action.

Noise can be divided into:: 1000Hz high frequency noise.

According to the time-varying characteristics, noise can be divided into steady noise, unsteady noise, fluctuation noise, intermittent noise and impulse noise.

Noise is caused by natural phenomena (see natural noise) and man-made. Therefore, it is also divided into natural noise and man-made noise.

Noise source:

(1) Traffic noise: including noise generated by motor vehicles, ships, subways, trains and airplanes. Due to the sharp increase in the number of motor vehicles, traffic noise has become the main source of urban noise.

(2) Industrial noise: noise generated by various equipment in the factory. The sound level of industrial noise is generally high, which brings great shadow noise pollution to workers and surrounding residents.

(3) Construction noise: mainly from the noise generated by construction machinery. Construction noise is characterized by high intensity, which mostly occurs in densely populated areas, seriously affecting the rest and life of residents.

(4) Social noise includes people's social activities and noise emitted by household appliances and audio equipment. Although the noise level of these devices is not high, they are closely related to people's daily life, which makes people fidget during rest, which is particularly annoying and easily leads to neighborhood disputes.

(5) Noise pollution in family life.

Noise pollution is harmful to people, animals, instruments and buildings, and its degree of harm mainly depends on the frequency, intensity and exposure time of noise. Noise hazards mainly include:

Noise damages hearing, which can induce many diseases, interfere with normal life and work, cause pathological changes of animals, and extremely strong noise will do harm to instruments, equipment and building structures.

Noise source: (1) Traffic noise includes noise generated by motor vehicles, ships, subways, trains and airplanes. Due to the sharp increase in the number of motor vehicles, traffic noise has become the main noise source in cities.

(2) Industrial Noise Noise generated by various equipment in the factory. The sound level of industrial noise is generally high, which has a great impact on workers and surrounding residents.

(3) The construction noise mainly comes from the noise emitted by construction machinery. Construction noise is characterized by high intensity, which mostly occurs in densely populated areas, seriously affecting the rest and life of residents.

(4) Social noise includes people's social activities and noise emitted by household appliances and audio equipment. Although the noise level of these devices is not high, they are closely related to people's daily life, which makes people fidget during rest, which is particularly annoying and easily leads to neighborhood disputes.

Prevention and control: the impact and harm of noise on people are directly related to the intensity of noise. In buildings, the measures to reduce noise are mainly sound insulation and sound absorption. Sound insulation is to isolate the sound source and prevent the noise generated by the sound source from spreading indoors. Planting trees on both sides of the road can insulate the houses on both sides. The sandwich structure made of porous materials and dense materials will also have good sound insulation effect. In order to eliminate noise, commonly used sound-absorbing materials are mainly porous sound-absorbing materials, such as glass wool, mineral wool, expanded perlite, perforated sound-absorbing board and so on. The sound absorption performance of materials depends on its roughness, flexibility, porosity and other factors. In addition, lawns and trees around buildings are also good sound-absorbing materials, so we plant flowers and trees, which not only beautify our living and learning environment, but also prevent noise from polluting the environment.

Suggestion: (1) In order to protect people's hearing and health, the allowable value of noise is 75~90 dB.

(2) Ensure conversation and communication, and the allowable value of environmental noise is 45~60 decibels.

(3) It is recommended to sleep at 35~50 decibels.

I hope you are good to you.