After five years' efforts, the noise sources of 1 1794 from 1034 factories in China were tested and analyzed, and the noise exposure of 62726 workers was investigated. The physiological effects of noise are deeply discussed, especially the influence of noise on heart and brain is analyzed by computer, and the linear relationship between noise level and EEG function index is obtained. The relationship between occupational noise exposure deafness positive rate and noise level, occupational noise exposure neurasthenia syndrome and noise level, linear relationship between noise annoyance and noise level, and noise and telephone interference. On this basis, the noise standards and noise limits at the factory boundary of industrial enterprises (including production workshops, control rooms, offices, clinics and schools) are given. On the basis of summarizing the experience of noise control technology and engineering practice at home and abroad since 1980s, the specifications of overall noise control design, sound insulation design, noise elimination design, sound absorption design and vibration isolation design for industrial enterprises are given. In order to provide a basis for the formulation of noise standards, with the support of relevant departments in the State Council, a specification compilation group was organized by 40 enterprises in 13 provinces and cities in the first half of 1980s.
Nearly 100 noise control pilot projects have been carried out. The practice of control engineering involves aerodynamic noise sources such as fans, compressors, internal combustion engines and boiler exhaust, as well as mechanical noise sources such as air hammer, tooth cutter, winding machine, jade cutting grinder, manual grinder, bearing steel ball filing machine and ball polishing machine. 95% of the projects meet the requirements of 90dBA, of which 90% meet the requirements of 85dBA. This large-scale engineering practice not only provides an example for noise control design and implementation of this specification, but also verifies that most industrial enterprises can meet the noise limit requirements set by this specification through their efforts.
In this way, the standard specification 1985 12 was approved and promulgated by the State Planning Commission of People's Republic of China (PRC). It is named as People's Republic of China (PRC) national standard GBJ 87- 1985 "Code for Design of Noise Control in Industrial Enterprises". The approval and promulgation of this design code marks the birth of noise control project. Since then, noise is no longer a subject of noise science or noise control within the scope of physical acoustics, but a subject field in engineering and industry. This subject has not only theory, but also engineering design and product design, which has really become an integral part of engineering discipline. It can be said that noise control engineering is a new science and technology field which is intersected by physics, acoustics, mechanical engineering, architectural engineering, material science, chemical engineering, computer, mathematics, physiology and psychology. In 1980s, another important comprehensive noise standard-Urban Regional Environmental Noise Standard was edited by Institute of Acoustics, Chinese Academy of Sciences, jointly compiled by Beijing Labor Insurance Institute, Tongji University and Beijing Environmental Monitoring Station, and promulgated by the State Council Environmental Protection Leading Group.
In particular, Professor Ma, as a consultant, gave strong guidance to the above several important comprehensive noise standards.
During this period, some noise limit standards for transportation and general machinery were also promulgated. For example, motor vehicle noise allowable standard, marine ship noise level regulation, inland river ship noise level regulation, marine diesel engine radiated air noise limit, aircraft noise airport ambient noise standard, general small gasoline engine noise limit, rotating motor noise limit, earth-moving machinery driver seat vibration test method and limit, and so on. During this period, the Environmental Vibration Standard for Urban Areas was promulgated.
This series of large-scale activities in the field of noise since the 1980s, accompanied by the birth of noise control project, has made China's noise control work enter a new stage of comprehensive management of the whole plant and regional environment from a single machine, and a few scientific research and design units have spontaneously studied and entered a new stage of government management with rules to follow. Noise control has developed from scientific research in a few acoustic units to engineering practice and product design. The noise team in China has also developed from a few units with more than a dozen people in the early 1960s to twenty or thirty units, with thousands of scientific and technical personnel, including a group of accomplished senior researchers and senior engineers and technicians. These years of in-depth research work has also made China enter the international advanced ranks in the fields of sound absorption structure, airflow noise and muffler, physiological effect of noise, noise standard and noise control engineering. What is more exciting is that China's noise control equipment manufacturing industry has grown from scratch. By the end of 1980s, a noise control equipment and instrument manufacturing industry with hundreds of factories and tens of thousands of employees had been formed, producing various mufflers, sound absorbers, sound insulation components, shock absorbers and acoustic measuring instruments.
With the birth of noise control engineering, academic activities in the field of noise control engineering are extremely active. 1982, the first national conference on noise control engineering was held in Huangshan, with 70 papers/kloc-0. 1984, 2nd National Noise Control Engineering Conference (Hangzhou Conference), 180 paper, 1986, 3rd National Noise Control Engineering Conference (Xi 'an Conference), 200 paper, 1988. 1987, the 16th International Symposium on Noise Control Engineering was held in Beijing, and experts from all over the world gathered in Beijing to exchange the research progress of noise control engineering. China's achievements in noise control engineering have attracted the attention and attention of peers all over the world.
A number of books on noise control were published in 1980s, such as Noise and Vibration Control by L.L.Beranek,1971; Faulkner, Handbook of Industrial Noise Control,1976; Harris, noise control manual,1979; China also has his own books, such as, edited by Ma, Noise Control,1987; Fang Danqun, Aerodynamic Noise and Muffler,1978; Fang Danqun, Wang Wenqi, Sun Jiaqi, noise control,1986; Zhao Songling noise reduction and isolation,1985; Zheng Changju, Hong, et al., Environmental Noise Control Project,1988; Lv Yuheng et al., Selection Manual of Noise and Vibration Control Equipment.1988; Ren Wentang, Industrial Noise and Vibration Control Technology,1989; Sun Jiaqi et al., Harm of Vibration and Control Technology, 1989. The professional publication Noise and Vibration Control edited by Yan Jikuan was also officially published. Whether in Europe, America or China, the 1980s witnessed the prosperity of noise control and ushered in the birth and development of noise control engineering. Since 1990s, noise control engineering has been developing vigorously in the world.
The noise control project gives "noise control" to industry. In the past 20 years, countries all over the world have made outstanding achievements in noise reduction. Taking aircraft noise as an example, the reduction from 120 WECPNdB in the 1960s to 80 WECPN dB now is the comprehensive result of investing a lot of manpower, material resources and financial resources, and adopting many technologies such as strengthening noise elimination, sound insulation, active noise control, and optimizing body design. It's not easy.
However, with the increasingly strict restrictions on aircraft noise in various countries and fierce commercial competition, in recent years, both the United States and Europe have launched new silent aircraft plans. For example, Lockheed Martin of the United States is developing a "quiet supersonic transport aircraft" with a maximum flight speed of 1.6 times the speed of sound. It will adopt a series of newly developed aerodynamic technologies, especially the special nose and inverted V-shaped tail rudder design. The noise level of this plane will be 20 decibels lower than that of Concorde. It will not disturb the residents on the ground during the flight. It is expected that this new type of aircraft will be put into use before 20 12.
Another group of R&D work is carried out by Cambridge-Massachusetts Institute of Technology (CMI). This is a new design of efficient wing-body integrated passenger aircraft. The goal of SAX40 wing-body fusion silent aircraft is that the weighted average noise level around the airport is 63 dB (dBA), which is lower than the road traffic noise level, and the noise generated by the aircraft is almost inaudible in the surrounding areas of ordinary airports. SAX40 has taken various measures to reduce noise, and its key technologies include: curved central lifting body, which can make low-speed approach and efficient cruise; Embedded distributed propulsion system, including super Gao Han ratio engine and adjustable thrust vector nozzle; There is no conventional flap on the wing, and its downward curved leading edge can be deployed smoothly. The aileron is equipped with a trailing edge brush to reduce the noise when entering the field. The rectified landing gear can eliminate noise sources and so on. "Silence" is the first key of the research plan of SAI civil large aircraft, which shows that noise is the key problem of new large civil passenger aircraft in recent 20 years.
The primary task of American "sea wolf" class attacking nuclear submarines is anti-submarine, and noise reduction is very important for it. The noise control methods mainly include: adopting a new type of "pump jet propeller" for the first time to solve the propeller noise problem; Natural circulation reactor is adopted in nuclear power plant to reduce loop noise; ; The high noise reduction gearbox is replaced by steam turbine electric propulsion; It is the first time to adopt "active noise control technology", and all units adopt effective noise and vibration control technology. It is the first time to adopt "active noise control technology". As a result, the noise of the "sea wolf" is lower than that of the ocean background, making it a real "quiet" submarine.
Look at car noise, which is the most important part of traffic noise. In Europe and America, the provisions of automobile noise standards are more and more strict. At the same time, noise, vibration, comfort and other factors have also become important indicators of automobile product quality. In order to meet the higher requirements of customers, it is also a thorny issue for automobile manufacturers. Because the noise of cars has been reduced many times. Since 1970s, people have adopted many methods to reduce automobile noise, such as automobile exhaust muffler, improvement of automobile mechanical structure, optimized vibration isolation design of engine and vehicle, etc. On this basis, it is much more difficult to reduce it by several decibels than the original reduction of 10 decibels. After the car noise drops to 75 decibels, there is no main noise source, and all parts are similar. Through testing and analysis, the noise of each part, such as exhaust noise, tire noise, engine noise, gear noise, exhaust noise, transmission noise, etc. After careful calculation, how much noise contribution of each part should be reduced to reduce the noise of the whole vehicle by several decibels. This is a very meticulous and arduous work, and it is also the main goal that the European and American automobile industries are going all out to tackle key problems. In recent years, road noise has also attracted people's attention. It is estimated that noise costs the EU 654.38+000 billion annually? 40 billion dollars, about half of which comes from road noise. One way to solve the road/tire noise is to build a single-layer porous road on asphalt concrete subgrade, which has been laid for hundreds of miles in Europe. In addition to reducing noise, porous surfaces also help to drain water, potentially reducing traffic accidents.
For general machinery and household appliances, ISO also gives a "Guide to Low Noise Machine Design". In the past twenty years, low-noise machines have become fashionable goods in all countries of the world, and manufacturers are scrambling to develop low-noise equipment as bargaining chips in the market. In recent years, China has also made great achievements in the research and development of low-noise machinery and equipment, such as the low-noise cooling tower developed by Shanghai Jiaotong University, Tsinghua University, the Fourth Research Institute of the Ministry of Machinery, Beijing Labor Insurance Institute and Zhejiang Lianfeng Group, the low-noise axial fan developed by Shanghai Jiaotong University, CSSC 7 1 1, Shangyu Fan Factory, and the low-noise woodworking machinery developed by CSSC No.9 Institute.
Noise reduction of sound source greatly enriches the knowledge treasure house of noise control engineering. The research and application of active noise control, that is, electronic muffler, has also made important progress. The excellent work of P.A.Nelson of Southampton University in England has turned the idea of many years into reality in the cockpit of an airplane and brought active noise control into a practical stage. After that, active noise control has achieved remarkable noise reduction effect in ships, carriages and central air conditioning pipes. In this field, Institute of Acoustics, Chinese Academy of Sciences, Nanjing University and Northwestern Polytechnical University have published a series of theories and works.
In the field of noise control engineering theory, great progress has been made in the theory of vibration, sound radiation, sound field distribution and their coupling, especially in the rapid progress of computer and information technology. Statistical energy analysis (SEA) and finite element method have successfully entered the field of noise control engineering theory, which simplifies many quite complicated acoustic calculations, such as missile and aircraft noise. The computer calculates autocorrelation function, cross-correlation function and coherence function by using fast Fourier integral, which enables people to identify noise sources and measure sound intensity to a new height. The prediction and pre-evaluation of urban traffic noise have also achieved important results.
Since the 1990s, due to the wide application in architectural acoustics and other fields, such as the successful application of transparent microperforated board developed by Cha Xueqin, the sound absorption materials and technology of microperforated board have been highly valued by colleagues at home and abroad again. Zhao Songling and Liu Ke have done a lot of research work on the nonlinearity of microperforated plates. Jing Tian, Li Xiaodong, Mao Dongxing and Zhang Bin. The application of micro-perforated plate has been deeply studied. According to the development of materials and production technology, many researchers put forward a variety of micro-hole processing methods, such as laser drilling, electro-etching, chemical etching, high-speed injection and so on. New products such as transparent microplate and variable aperture microplate have been produced. Other new sound-absorbing materials are constantly emerging, such as foam glass, foam plastic, metal sintered plate, foam metal and so on.
In recent years, Zhejiang University's research on the subjective annoyance of discontinuous sound sources and low-frequency environmental noise, China National Environmental Monitoring Center, Environmental Engineering Evaluation Center of the Ministry of Environmental Protection and many other units' research work on traffic noise monitoring and prediction, and the work of the Ministry of Railways system on railway and train noise have all promoted the development of noise control engineering.
The development of noise control engineering has greatly promoted the industrialization of noise control. Nowadays, the noise control industry has been formed in the world. In Europe and America, you can buy high-quality sound absorbers, silencers, sound insulation components, shock absorbers and acoustic measuring instruments from many manufacturers and suppliers of noise control equipment and acoustic measuring instruments. There are also many consulting companies to design and solve the noise problem for you. In China, the general noise control equipment industry has made great progress, forming a series of standardized production bases for general noise control equipment and acoustic measuring instruments, and more than 500 enterprises specializing in noise and vibration control products manufacturing and engineering technical services. There are tens of thousands of employees. In particular, mufflers matched with automobiles and some mechanical equipment have been produced on a large scale. For example, some enterprises in car muffler have an annual production capacity of more than 654.38+10,000 sets, with an annual output value of several hundred million yuan. At present, the annual output value of car muffler in China has reached more than one billion yuan. In recent years, the scale of noise control projects has become larger and larger. In European and American countries, the overall noise control of airports and the noise barrier in expressway will cost millions, tens or even hundreds of millions of dollars. In China, there are also tens of millions of noise control projects, such as Beijing Luchuang Acoustics Co., Ltd., 1) Beijing Taiyanggong gas-fired thermal power plant noise control project of 45 million yuan; 2) The noise control project of Zhengchangzhuang Thermal Power Plant is 53 million yuan; 3) The noise control project of Capital Airport Terminal is 20 million yuan. Shenzhen Electromechanical Industry Co., Ltd., 1) GE Xiamen aero-engine test bench, 3 1 10,000; 2) Shenzhen Metro Phase I 1, Line 3#, Guangzhou Metro Line 3#, Line 5# and Chongqing Metro Line 2#, all of which are more than170,000; Shanghai Shenhua Acoustics Equipment Co., Ltd., Shanghai Xinhuanet Environmental Protection Company and a series of road noise barriers are also large-scale noise control projects with more than 10 million yuan. In these projects, noise control engineering has fully played its role.
In China, there are more than 50 units engaged in noise and vibration control research, design, teaching and monitoring, with thousands of technicians. Form a strong technical team. As the backbone of the noise control project, the team has established a relatively complete system of noise control regulations and standards in China. For example, People's Republic of China (PRC) Law on the Prevention and Control of Environmental Noise Pollution, Environmental Noise Quality Standard, Noise Emission Standard, Emission Standard of Various Noise Sources, Technical Standard of Various Noise Control Equipment, Noise Test and Prediction Evaluation Standard, and Noise Control Technical Standards and Specifications are more than 100. A considerable number of papers have been published, systematically summarizing and introducing the latest achievements and development trends of noise and vibration noise technology at home and abroad, which has played an important role in promoting the development of noise control engineering. In 2008, the Ministry of Environmental Protection approved Beijing Labor Insurance Institute to build "National Environmental Noise Control Engineering Technology Center", which is also a major event in the field of noise control engineering and will certainly play an important role in noise control.
Following 1987 held the International Conference on Noise Control Engineering in China, the 37th International Conference on Noise Control Engineering was held in Shanghai in June 2008. The contents of the conference mainly involve environmental noise, architectural acoustics, noise and vibration control, noise policy and management, numerical model and simulation calculation, signal processing and measuring instruments, soundscape, sound quality, active control of noise and vibration, influence of vibration and shock, structural acoustics, aviation acoustics, occupational noise and its protection, noise mapping, aircraft and vehicle noise, beamforming and acoustic holography. Jing Tian, the president of this conference, gave a report on the research progress of microperforated board at the conference, and at the same time reported a lot of the latest domestic research results at the conference, so that scholars all over the world can further understand the research characteristics of China in this field. Two international noise control engineering conferences were held in China, which was the recognition of the development and progress of noise control technology in China by the international noise community, and also marked a new milestone in noise control in China, which promoted the development and perfection of noise control engineering in China.
In 2009, the National Symposium on Noise Control Engineering has entered the 1 1 session, which was jointly organized by nine societies and associations related to noise control engineering, marking the success and prosperity of noise control engineering in China.