The main measures are: ① sound in the propagation of energy is with the increase in distance and attenuation, so the noise source away from the need to be quiet place, can achieve the purpose of noise reduction. ② sound radiation is generally directional, in the same distance from the source and the direction of the different places, the received sound intensity is different. However, most of the sound source to low-frequency radiation noise, directionality is very poor; with the increase in frequency, directionality is enhanced. Therefore, controlling the propagation direction of noise (including changing the emission direction of sound sources) is an effective measure to reduce noise, especially high-frequency noise. ③Establish sound insulation barriers, or utilize natural barriers (earth slopes, hills), as well as utilize other sound insulation materials and sound insulation structures to block the propagation of noise. ④ Apply sound-absorbing materials and sound-absorbing structures to convert the sound energy of the propagating noise into heat energy, etc. ⑤ Adopt reasonable urban noise prevention planning in urban construction. In addition, take vibration isolation measures for noise generated by solid vibration to attenuate the propagation of noise. In order to prevent noise, Prof. Ma Dayou, a famous acoustician in China, has summarized and studied the hazards and standards of all kinds of noises existing at home and abroad, and put forward three suggestions:
1) In order to protect people's hearing and health, the permissible values of noises are 75~90 decibels.
②To safeguard conversation and communication, the permissible ambient noise level is 45~60 dB.
③The recommended noise level for sleeping time is 35~50dB.
China's psychological community believes that the control of noise environment, in addition to considering the human factor, must also take into account the economic and technical feasibility. Adequate noise control must take into account the entire system consisting of the noise source, the path of transmission, and the recipient. Measures to control noise may address all or any of these three components. Noise control includes:
①Control of noise sources. Reduce the noise of the source, industry, transportation industry can choose low-noise production equipment and improve the production process, or change the movement of the noise source (such as damping, vibration isolation and other measures to reduce the vibration of the solid sound-emitting body) Most of the city's sound source comes from the highway traveling bus car whistles and large squares Chinese amazons dance square dance playback of sound, are to the surrounding residential areas rest residents caused a certain The impact of the sound of the square dancers on the residents in the surrounding residential areas. We can take to each woman to wear a headset to play music, to be able to reduce the noise from the root.
②Block the spread of noise. Reduce noise in the transmission pathway, control the spread of noise, change the sound source has been issued by the noise transmission pathway, such as the use of sound absorption, sound insulation, sound barriers, vibration isolation and other measures, as well as rational planning of urban and building layout.
3) At the human ear to attenuate noise. Noise protection of the recipient or the recipient organ, in the sound source and transmission pathway can not take measures, or to take acoustic measures still can not achieve the desired effect, it is necessary to take protective measures for the recipient or the recipient organ, such as long-term occupational noise exposure of workers can wear ear plugs , ear muffs or helmets and other ear protectors.
Noise control is technically mature, but because of the modern industry, transportation industry is very large, to take the noise control of the number of enterprises and places, so in the prevention of noise problems, must be from the technical, economic and effect of the aspects of a comprehensive trade-off. Of course, specific issues should be specifically analyzed. Outside the control room, design room, workshop or long-term work of employees, the intensity of noise to be low; warehouse or less people to go to the workshop or open space, the noise is slightly higher can be. In short, the treatment of different times, different locations, different nature and different duration of the noise, there should be some difference.