Noise control and noise reduction equipment
Noise control, soundproof room, soundproof room, soundproof door, soundproof window, exhaust muffler, soundproof room, all kinds of sound-absorbing materials, sound-absorbing boards, sound-absorbing bricks, sound-absorbing boards, soundproof curtains, soundproof barriers and new technology electronics for reducing noise are applied to entertainment centers, power plant fans, generator sets, air compressors, air hammers, central air conditioners and cooling water towers.
Noise problem has long been the biggest culprit of environmental pollution, which is a patented technology invented by German physicist Paul Ruger in 1933. As we all know, noise propagates in the form of sound waves in the atmosphere. The noise that people usually hear is a combination of high-amplitude and low-amplitude sound waves. If two sound waves meet and overlap, the noise will be cancelled out.
19 10 German doctor robert koch, the founder of world bacteriology, predicted: "One day, in order to survive, human beings will have to fight against noise, just like cholera and plague." His words became a reality in just a few decades. Noise is very harmful to human health. According to the data of Beijing CDC, 0/0% of occupational diseases in Beijing are caused by noise, ranking first in the city. Director Jin told reporters that it is now recognized internationally that noise has four major impacts: 1. Nervous system-insomnia, trance; 2。 Cardiovascular system-hypertension, leading to acute attack in patients with heart disease; 3。 Immunity-decreased immunity increases the incidence of various diseases; 4。 Hearing-Long-term high noise leads to hearing loss. Recently, scientists in the United States, Japan, France and other countries have also found that when the noise intensity exceeds 90 decibels, people's vision will be weakened. Experts said that every 3 decibels reduction in traffic noise is equivalent to 1 times the distance from the sound source, and the noise reduction effect is obvious. How do ordinary people avoid the harm of noise in their lives? According to experts, according to national regulations, the noise standard of residential areas is below 50 decibels during the day and below 40 decibels at night. If it exceeds this standard, you can find relevant departments to solve it. In addition, with regard to indoor noise, we can make the walls of our homes rough, use wooden furniture, cotton curtains and carpets, or install sound-proof doors and windows-or use vacuum technology to reduce noise, all of which can play a role in reducing noise.
"Static Island" is to install a circle of speakers around the island and a circle of microphones around the external speakers (seven were used in the experiment, but there are actually 50) to let the noise fully come in. Then the noise is analyzed by computer, and the anti-noise wave with appropriate frequency is mathematically calculated, which is emitted by the inner ring horn to reduce the noise by noise. The higher the noise frequency, the more speakers are needed.
It is reported that during the experiment, "Quiet Island" reduced the surrounding noise by 20 decibels, while the noise people felt was almost reduced by half. The system is especially suitable for installation on the roadside with high noise. Due to the cost problem, it is estimated that it will take several years for "Quiet Island" to be put into practical use.
Acoustic causes of noise
There are all kinds of sound waves in the environment of human life, some of which are used to transmit information and carry out social activities, which are needed by people; Some will affect people's work and rest, and even endanger people's health. This is what people don't need, called noise. In order to improve the sound environment of human beings and ensure that the language is clear and easy to understand and the music is beautiful. Since 1950s, with the rapid development of industrial production and transportation, the urban population has increased dramatically, and there are more and more noise sources, resulting in increasingly intense noise pollution in human living environment. Therefore, it is necessary not only to improve the sound quality in the building, but also to control the noise in a certain spatial range inside and outside the building to prevent the harm of noise. The study of these problems involves physics, physiology, psychology, biology, medicine, architecture, music, communication, law, management and many other disciplines, thus producing environmental acoustics.
Study the generation, transmission and reception of sound and its physiological and psychological effects on human body; Study the technology and management measures to improve and control the quality of acoustic environment.
Sound quality design: theaters, cinemas, concert halls, conference halls and other buildings are places where people gather for cultural entertainment and social activities. The sound quality problems in these buildings are related to both reverberation time and so-called "sound field diffusion" (see sound field). On the one hand, the sound quality control should strengthen the effective sound reflection in the sound propagation path, make the sound energy evenly distributed and diffused in the building, and ensure that the direct sound heard by the receiver has appropriate loudness; On the other hand, it is necessary to adopt various sound-absorbing materials or structures to eliminate unfavorable sound reflection and sound energy concentration in buildings and control reverberation time. In addition, internal and external noise interference should be reduced (see room acoustics).