Interfere with people's rest, study and work by the noise pollution caused by mechanical vibration or more due to the motion of fluid. Quiet environment, the sound is about 30 dB noise over 50 decibels will affect sleep and rest, 90 decibels or more, will damage people's hearing, affecting the efficiency of serious or induced hearing loss caused by other diseases.
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No. 2
Environmental pollution caused by the noise. Usually refers to industrial production, transportation, construction and social life, and man-made noise pollution. The masts of human hearing damage mainly affecting the rest and work, reduce labor productivity, hinder communication and liaison. No backwash effects, noise, once stopped, contamination immediately disappear.
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zào shēng wū rǎn
By the interference or harmful noise (such as cars or jet noise) the formation of environmental pollution
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No. 4
zàoshēngwūrǎn With the development of modern industry, environmental pollution also with produce, noise pollution is a kind of environmental pollution has become a major hazard to humans. The impact of noise on people and with the extent of damage is directly related to the strength of the noise. In buildings, the measures taken to reduce noise and sound insulation and sound absorption mainly. The acoustic sound source is isolated to prevent the propagation of noise generated by the sound source to the interior. In the street was lined with trees on both sides of the housing can play acoustic effect. In the dense material in the multi-storey buildings separated by a porous material made of a sandwich structure which will play a very good sound insulation effect. To eliminate noise, sound-absorbing materials are mainly used porous sound-absorbing material, such as glass wool, mineral wool, perlite, piercing sound-absorbing panels. Sound absorption properties of the material depends on its roughness, flexible, porous and other factors. In addition, the buildings around the lawn, trees, etc. are also very good sound-absorbing material, so we planted flowers and trees, not only beautify the environment we live and learn, but also prevention of noise pollution on the environment. Noise pollution and water pollution, air pollution is seen as the world three major environmental problems. Sound vibrations caused by the object, in the form of a wave propagated in a medium (such as solid, liquid, gas) in the. We often hear the sound of air. Generally, the human ear can hear the sound frequency is 20 ~ 20,000 hz, referred to audible sound; below 20hz, called infrasound; than 20,000 hz, called ultrasound. We hear the sound of the tone depends on the level of frequency sound waves, high-frequency sound sounds sharp, and low frequency sound feels more boring. The size of the sound is the strength of the decision by the sound. From a physical point of view, noise is generated by a variety of different frequencies, the sound of different intensity messy combination of erratic made; tones are harmonious sound. Determine whether a voice belonging to the noise, only from the physics point of judgment is not enough, the subjective factors often play a decisive role. For example, the wonderful music for people who are listening to music is a musical, but are learning, rest or concentrate think people may be a noise. Even with one voice, when people in different states, different mood, the sound will produce different subjective judgments, then the sound may become noise or tone. Therefore, from a physiological point of view, people who interfere with rest, learn and voice work that does not require voice, referred to as noise. When the noise adverse impact on people and the surrounding environment, the formation of noise pollution. Mechanical characteristics of noise pollution by sound source can be distinguished: the noise disturbance gas, vibration noise generated by the solid, and the electromagnetic noise generated by the impact effect of the liquid produced by the electromagnetic noise. Noise can be divided according to the frequency of the sound: <400hz frequency noise, frequency noise 400 ~ 1000hz and> 1000hz frequency noise. Time-varying noise properties can be divided into: steady noise, non-stationary noise, rolling noise, intermittent noise and impulse noise. The main source of urban environmental noise are: ⑴ traffic noise, including noise motor vehicles, ships, subways, trains, airplanes and the like. Due to the rapid increase in the number of motor vehicles, making traffic noise as a major source of noise of the city. ⑵ various industrial equipment factory noise generated noise. Industrial noise sound level is generally higher, bringing a greater impact on workers and surrounding residents. ⑶ construction noise emitted mainly from the noise of construction machinery. Construction noise is characterized by greater intensity and occurred in densely populated areas, thus seriously affecting the rest of the life of the residents. ⑷ community noise, including noise people's social activities and household appliances, audio equipment can emit. Although the noise level of these devices is not high, but because of people's daily lives and closely linked, so that people are not quiet at rest, is particularly annoying, can easily cause neighborhood disputes. Noise pollution on humans, animals, instruments and building constitutes a hazard, the harm depends on the noise level of the frequency, intensity and exposure time. Noise hazards include: ⑴ noise on hearing damage Noise on the human body is the most direct harm hearing damage. When people enter the strong noise environment, exposure time, the ears will feel uncomfortable, even headaches and feeling. Leave the noise environment to a quiet place to rest for some time, the hearing will gradually return to normal. This phenomenon is called temporary threshold shift, also known as auditory fatigue. However, if people are long-term work in strong noise environment, auditory fatigue can not be restored in time, and the inner ear organ organic disease will occur, that the formation of permanent hearing threshold shift, also known as noise-induced hearing loss. If people suddenly exposed to very strong noise environment, auditory organ trauma occurs abruptly, causing the eardrum rupture, lost bleeding, acute stripped screw from the basement membrane, which may cause complete loss of hearing ear, deafness appears Shock. Studies have shown that noise pollution is a major cause of presbycusis. In addition, hearing damage also with the environment and living related occupations, such as rural presbycusis incidence is lower than the city, textile workers, blacksmith blacksmith and more hearing damage compared with their peers. ⑵ noise can induce a variety of diseases Because of noise in the brain via the auditory organ of the central nervous system, which affects various organs of the body, so the noise in addition to damage to human hearing, it will also bring harm to other body systems. Since the effect of noise, will produce headaches, brain swelling, tinnitus, insomnia, fatigue, weakness and general memory loss and other symptoms of neurasthenia. People working in long-term high-noise environments compared with the case of low-noise environments, the incidence of hypertension, atherosclerosis and coronary heart disease two to three times higher. Visible noise can cause cardiovascular disease. Noise can also lead to digestive disorders, causing indigestion, loss of appetite, nausea, vomiting, gastrointestinal problems and increased incidence of ulcer disease. In addition, noise, visual organs, endocrine function, and normal development of the fetus, etc. will have an impact. People work and live, and general health in the high noise levels fall gradually, weakened resistance to disease, induced a number of diseases, but also about the personal and physical factors, can not be generalized. ⑶ noise of a normal life and work The impact of noise on human sleep is great, people even in sleep, auditory stimulation should bear the noise. Noise can cause more than a dream, easily awakened, decreased sleep quality, etc., sudden impact of noise on sleep is more prominent. Noise can interfere with people's conversations, work and learn. Experiments show that when people suffer a sudden and noise disturbance, we should focus on the idea of losing four seconds. According to statistics, the noise will reduce productivity of 10 to 50%, with the increase of noise, the error rate rises. Thus, the noise will distract people's attention, resulting in slow response, fatigue, decreased productivity, error rate rise. Security will be masking noise signals such as alarm signals and vehicle signals, resulting in an accident. Effect of Noise on animals ⑷ Noise can be auditory organs of animals, visual organs, internal organs and central nervous system caused by pathological changes. Noise on animal behavior have a certain influence, can make the animal loses the ability to control behavior, irritability, loss of normal phenomena, strong noise will cause the animal to death. Bird feathers appear in the noise off, affecting spawning rate. ⑸ exceptionally strong noise on equipment and building structures harm Experimental studies have shown particularly strong noise can damage equipment, and even the equipment failure. Noise and other effects of structure and installation of equipment and noise intensity, frequency, and the equipment itself factors. When the noise level exceeds 150db, would seriously damage the resistors, capacitors, transistors and other components. When the noise is particularly strong effect on the rocket, spacecraft and other mechanical structures, due to repeated acoustic effect by alternating load, the material will produce fatigue and fracture, a phenomenon called acoustic fatigue. General noise almost no effect on the building, but the noise level exceeds 140db, construction began on the damaging effects of light. For example, when passing at low altitude supersonic aircraft, the head and tail of the aircraft will produce pressure and density of the mutation, the formation of n-shaped shock wave after ground reflection, sounds like explosions, this special sound when the noise is called boom to the ground . In the role of sound boom, buildings will be subject to different degrees of damage, such as damage occurs doors, broken glass, cracked walls, plaster crashing, chimneys collapsed and so on. Since the boom sound attenuation slow, so far spread, affecting a wider scope. In addition, the use of air hammer nearby buildings, piling or blasting, can lead to damage to the building.
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What is noise pollution
With the development of modern industry, environmental pollution also with produce, noise pollution is a kind of environmental pollution has become a major hazard to humans. Noise pollution and water pollution, air pollution is seen as the world three major environmental problems. Noise is the sound made when issuing the random vibration shedder. Sound vibrations caused by the object, in the form of a wave propagated in a medium (such as solid, liquid, gas) in the. We often hear the sound of air. Generally, the human ear can hear the sound frequency is 20 ~ 20,000 Hz, is called an audible sound; below 20Hz, called infrasound; higher than 20,000 Hz, is called ultrasound. We hear the sound of the tone depends on the level of frequency sound waves, high-frequency sound sounds sharp, and low frequency sound feels more boring. The size of the sound is the strength of the decision by the sound. From a physical point of view, noise is generated by a variety of different frequencies, the sound of different intensity messy combination of erratic made; tones are harmonious sound. Determine whether a voice belonging to the noise, only from the physics point of judgment is not enough, the subjective factors often play a decisive role. For example, the wonderful music for people who are listening to music is a musical, but are learning, rest or concentrate think people may be a noise. Even with one voice, when people in different states, different mood, the sound will produce different subjective judgments, then the sound may become noise or tone. Therefore, from a physiological point of view, people who interfere with rest, learn and voice work that does not require voice, referred to as noise. When the noise adverse impact on people and the surrounding environment, the formation of noise pollution.
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Classification noise
Mechanical characteristics of noise pollution by sound source can be distinguished: the noise disturbance gas, vibration noise generated by the solid, and the electromagnetic noise generated by the impact effect of the liquid produced by the electromagnetic noise. Noise can be divided according to sound frequency: <400Hz low frequency noise, frequency noise 400 ~ 1000Hz and> 1000Hz frequency noise. Time-varying noise properties can be divided into: steady noise, non-stationary noise, rolling noise, intermittent noise and impulse noise. Noise caused by natural phenomena (see natural noise), it was for the cause. It is also divided into natural and man-made noise is noise.
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The main sources of noise
⑴ traffic noise: noise, including motor vehicles, ships, subways, trains, airplanes, etc. issued. Due to the rapid increase in the number of motor vehicles, making the traffic noise become a major source of noise in the city. ⑵ industrial noise: a variety of equipment noise generated by the plant. Industrial noise sound level is generally higher, bringing a greater impact on workers and surrounding residents. ⑶ construction noise: noise construction machinery mainly from the issue. Construction noise is characterized by greater intensity and occurred in densely populated areas, thus seriously affecting the rest of the life of the residents. ⑷ community noise, including noise people's social activities and household appliances, audio equipment can emit. Although the noise level of these devices is not high, but because of people's daily lives and closely linked, so that people are not quiet at rest, is particularly annoying, can easily cause neighborhood disputes. Characteristics of noise Both a nuisance noise, it has the characteristic of pollution, and as a sound, but also has acoustic properties. Pollution Characteristics (1) noise Since the noise nuisance are feeling, so it is different from other harmful pollution caused by toxic substances. First, it does not pollutants, namely noise propagation in the air did not leave anything to the surrounding environment of toxic substances; secondly, the impact of noise on the environment does not accumulate, not lasting, propagation distance is limited; noise source dispersion, And once the sound source stops sounding, the noise disappears. Therefore, the noise can not focus, require special methods to control it. Acoustic properties (2) noise Simply put, the noise is the sound, it has all the characteristics and laws of acoustics. But the impact of noise on the environment and the strength of its related noise stronger, the greater the impact. Measure the physical strength of noise is the noise level.
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Noise hazards
Noise pollution on humans, animals, instruments and building constitutes a hazard, the harm depends on the noise level of the frequency, intensity and exposure time. Noise hazards include: ⑴ noise on hearing damage Noise on the human body is the most direct harm hearing damage. When people enter the strong noise environment, exposure time, the ears will feel uncomfortable, even headaches and feeling. Leave the noise environment to a quiet place to rest for some time, the hearing will gradually return to normal. This phenomenon is called temporary threshold shift, also known as auditory fatigue. However, if people are long-term work in strong noise environment, auditory fatigue can not be restored in time, and the inner ear organ organic disease will occur, that the formation of permanent hearing threshold shift, also known as noise-induced hearing loss. If people suddenly exposed to very strong noise environment, auditory organ trauma occurs abruptly, causing the eardrum rupture, lost bleeding, acute stripped screw from the basement membrane, which may cause complete loss of hearing ear, deafness appears Shock. Studies have shown that noise pollution is a major cause of presbycusis. In addition, hearing damage also with the environment and living related occupations, such as rural presbycusis incidence is lower than the city, textile workers, blacksmith blacksmith and more hearing damage compared with their peers. ⑵ noise can induce a variety of diseases Because of noise in the brain via the auditory organ of the central nervous system, which affects various organs of the body, so the noise in addition to damage to human hearing, it will also bring harm to other body systems. Since the effect of noise, will produce headaches, brain swelling, tinnitus, insomnia, fatigue, weakness and general memory loss and other symptoms of neurasthenia. People working in long-term high-noise environments compared with the case of low-noise environments, the incidence of hypertension, atherosclerosis and coronary heart disease two to three times higher. Visible noise can cause cardiovascular disease. Noise can also lead to digestive disorders, causing indigestion, loss of appetite, nausea, vomiting, gastrointestinal problems and increased incidence of ulcer disease. In addition, noise, visual organs, endocrine function, and normal development of the fetus, etc. will have an impact. People work and live, and general health in the high noise levels fall gradually, weakened resistance to disease, induced a number of diseases, but also about the personal and physical factors, can not be generalized. ⑶ noise of a normal life and work The impact of noise on human sleep is great, people even in sleep, auditory stimulation should bear the noise. Noise can cause more than a dream, easily awakened, decreased sleep quality, etc., sudden impact of noise on sleep is more prominent. Noise can interfere with people's conversations, work and learn. Experiments show that when people suffer a sudden and noise disturbance, we should focus on the idea of losing four seconds. According to statistics, the noise will reduce productivity of 10 to 50%, with the increase of noise, the error rate rises. Thus, the noise will distract people's attention, resulting in slow response, fatigue, decreased productivity, error rate rise. Security will be masking noise signals such as alarm signals and vehicle signals, resulting in an accident. Effect of Noise on animals ⑷ Noise can be auditory organs of animals, visual organs, internal organs and central nervous system caused by pathological changes. Noise on animal behavior have a certain influence, can make the animal loses the ability to control behavior, irritability, loss of normal phenomena, strong noise will cause the animal to death. Bird feathers appear in the noise off, affecting spawning rate. ⑸ exceptionally strong noise on equipment and building structures harm Experimental studies have shown particularly strong noise can damage equipment, and even the equipment failure. Noise and other effects of structure and installation of equipment and noise intensity, frequency, and the equipment itself factors. When the noise level exceeds 150dB, would seriously damage the resistors, capacitors, transistors and other components. When the noise is particularly strong effect on the rocket, spacecraft and other mechanical structures, due to repeated acoustic effect by alternating load, the material will produce fatigue and fracture, a phenomenon called acoustic fatigue. General noise almost no effect on the building, but the noise level exceeds 140dB, construction began on the damaging effects of light. For example, when passing at low altitude supersonic aircraft, the head and tail of the aircraft will produce pressure and density of the mutation, the formation of N-shaped shock wave after ground reflection, sounds like explosions, this special sound when the noise is called boom to the ground . In the role of sound boom, buildings will be subject to different degrees of damage, such as damage occurs doors, broken glass, cracked walls, plaster crashing, chimneys collapsed and so on. Since the boom sound attenuation slow, so far spread, affecting a wider scope. In addition, the use of air hammer nearby buildings, piling or blasting, can lead to damage to the building. Noise is caused by a class of people agitated voice, or the volume is too strong and endanger human health. Noise pollution comes mainly from transportation, vehicle horns, industrial noise, construction, community noise such as concert halls, loudspeakers, loud morning and people and so on. Noise brings physical and psychological harm on the following main aspects: damage hearing. There are test showed: When people hear the continuous sound of a motorcycle, after eight hours of hearing will be impaired; If the rock concert, half an hour later, people will be hearing impaired. Harmful to the cardiovascular system, Chinese survey of urban noise and the health of residents showed that: noise areas every increase of 1 dB incidence of hypertension increased by 3%. Affect the nervous system, people impatient, irritable. Affect sleep, causing fatigue. From a psychoacoustic perspective, also known as noise noise generally refers to inappropriate or uncomfortable auditory stimuli. It is a composite having a non-periodic sounds and the frequency of vibration of a large number thereof. In short, the noise is aperiodic sound vibrations. Its irregular waveform sonic sounds harsh feel. From the social and psychological sense, all hinder people learn, work and rest and engender a feeling of uncomfortable sounds, called noise. As the sound of water, beat sound, rustle, the roar of machinery, etc., are noise. It is measured in decibels. Zero dB is the lowest intensity audible sound. Noise with high intensity and low intensity of the points. Low-intensity noise in general physical and mental health of the people there is no harm, but in many cases also help improve work efficiency. The main high-intensity noise from industrial machinery (such as weaving machines, lathes, air compressors, picks, blower, etc.), modern means of transport (such as cars, trains, motorcycles, tractors, airplanes, etc.), tweeter, construction sites as well as shopping malls, sports and entertainment venues, such as the noise. These high-intensity noise harm people's body, people feel tired, negative emotions, or even cause disease. High-intensity noise, only damage human hearing, and have varying degrees of impact on the nervous system, cardiovascular system, endocrine system, digestive system and vision, intelligence and so on. If people living in long-term work and 95 dB noise environment, about 29% will lose hearing; Even if only 85 db noise of people, there are 10% of people would deafness occurs; 120 to 130 decibels of noise, can make people feel ear pain; stronger noise causes hearing organ damage. In the nervous system, the noise will make people strong headache, dizziness, fatigue, insomnia, restlessness, memory loss and other syndromes, EEG slow wave increases, the autonomic nervous system dysfunction; in the cardiovascular system, strong noise will makes the pulse and heart rate change occurs, blood pressure, cardiac arrhythmia, conduction block, peripheral blood flow changes; in the endocrine system, strong noise will make people appear hyperthyroidism, adrenal enhanced basal metabolic rate up high, sexual dysfunction, menstrual disorders; in the digestive system, the noise will make people appear strong digestive hypothyroidism, stomach disorders, gastric acid reduction, loss of appetite. In short, strong noise causes the body to a series of physiological and pathological changes. Some 202 people had to work up to 95 db in noise environment conducted surveys, dizziness, accounted for 39%, accounting for 32% of insomnia, headaches, 27%, 27% stomach, accounting for 27% of flustered, memory recession accounted for 27%, accounting for 22% of the up_set_, poor appetite, 18%, 12% hypertension. Therefore, we can not be taken lightly and strong noise, measures should be taken to prevent it. Of course, people are more sensitive to noise, there is a big difference between the individual, some people are more sensitive to noise, and some people have strong adaptability to the noise, but also with people's needs, emotions and other psychological factors. Regardless of the differences between people of strong noise will always need to be prevented. Long-term pregnant women over 50 db noise in the environment, make the endocrine glands dysfunction and mental stress and endocrine system disorders. Causes severe high blood pressure, fetal hypoxia ischemia, leading to miscarriage or fetal malformation. The high-decibel noise can damage the fetal auditory organs, resulting in some of the affected area. Affect brain development, resulting in children with mental retardation. Malignant stimulus noise, seriously affecting the quality of our sleep and can cause dizziness, headache, insomnia, dreams, memory loss, inability to concentrate, nausea and other symptoms of neurasthenia, Yu Tu, stomach pain, bloating, loss of appetite and other gastrointestinal sluggish symptoms. Nutritionists study found that noise can make the body of vitamins, trace elements amino acid consumption, Valley nitric acid, nitric acid, etc. must rely on nutrients increases affect health; noise makes the adrenal glands increased heartbeat, increased blood pressure, easily lead to a heart attack; make noise while human saliva, gastric secretion, reduce gastric acid, thus suffering from gastric ulcer and duodenal ulcer. Harmful to the cardiovascular system, the noise of the city and the residents of the health survey showed that: noise area increases by 1 dB incidence of hypertension increased by 3%. · Affect the nervous system, people impatient, irritable. · Affect sleep, causing fatigue.
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Prevention of noise pollution
To prevent noise, the sound of the famous scientist Professor Ma Taiyou was summarized and studied the existing types of hazards and noise standards at home and abroad, put forward three suggestions: (1) In order to protect people's hearing and physical health, noise allowable value at 75 to 90 decibels. (2) protect conversations and communications liaison, environmental noise allowable value at 45 to 60 decibels. (3) proposed in the sleep time of 35 to 50 db. The impact of noise on people and with the extent of damage is directly related to the strength of the noise. In buildings, the measures taken to reduce noise and sound insulation and sound absorption mainly. The acoustic sound source is isolated to prevent the propagation of noise generated by the sound source to the interior. In the street was lined with trees on both sides of the housing can play acoustic effect. In the dense material in the multi-storey buildings separated by a porous material made of a sandwich structure which will play a very good sound insulation effect. To eliminate noise, sound-absorbing materials are mainly used porous sound-absorbing material, such as glass wool, mineral wool, perlite, piercing sound-absorbing panels. Sound absorption properties of the material depends on its roughness, flexible, porous and other factors. In addition, the buildings around the lawn, trees, etc. are also very good sound-absorbing material, so we planted flowers and trees, not only beautify the environment we live and learn, but also prevention of noise pollution on the environment. Our psychology profession that control noise environment, in addition to considering the human factor beyond the economic and technical feasibility must take into account. Adequate noise control, noise sources must be considered, acoustic way, by the tone of the entire system consisting of persons. Noise control measures can be against any part of the three parts or one. Noise control include: (1) reduce the sound source noise, industrial, transportation can use low noise production equipment and improve production processes, or change the noise source of exercise (such as damping, vibration isolation and other measures to reduce the solid body sound). (2) to reduce acoustic noise in the way, to control the spread of noise, change the route of transmission noise source has been made, such as the use of sound-absorbing, sound insulation, sound barriers, isolation and other measures, and the rational planning of urban and architectural layout. When the acoustic measures (3) by the sound or noise protection by organ sound, you can not take steps on the sound source and route of transmission, or take still can not achieve the desired results, you need to sound by sound or by an organ to take protective measures such as long-term occupational noise exposure workers can wear earplugs, earmuffs or ear protection helmet. While noise control is now technically mature, but because of modern industry, transport large, noise control to take quite a large number of companies and establishments, and therefore prevent noise problems, we must respect the technical, economic, and effects comprehensive trade-offs. Of course, the specific issues should be specific analysis. In the control room, design room, local shop or long-term workers, the intensity of the noise is lower; Treasury less people go to shop or open areas, a number slightly higher noise is possible. In short, the treatment of different times, different places, different properties and different durations of noise, there should be a difference. [Some] approach to combat noise pollution : ① in the propagation of acoustic energy is attenuated with distance, so far away from the noise source needs a quiet place, you can achieve the purpose of noise reduction. ② General acoustic radiation directivity, at the same distance from the sound source direction is different locations, the received sound intensity is different. However, most of the radiation source to the low frequency noise, poor directivity; with increasing frequency, the directivity enhanced. Therefore, the control of noise propagation direction (including changes in the emission direction of the sound source) are particularly effective measures to reduce noise of high frequency noise. ③ build noise barriers, or the use of natural barriers (slopes, hills), and the use of other insulation materials and insulation structure to block noise transmission. ④ application of sound-absorbing material and absorbing structure, the propagation of noise sound energy into heat energy and so on. ⑤ in urban construction, the use of anti-noise sound urban planning. Moreover, the vibration noise generated by the solid vibration isolation measures to attenuate noise transmission.
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The use of noise
While noise is one of the world's four major hazards, but it is useful to: Noise weed scientists found that different plants for different noise is not the same degree of sensitivity. According to this reasoning, people produce noise Zapper. This noise is the noise emitted by weeding weed seeds can germinate in advance, so that you can use to get rid of weeds before the drug crop, use the "murderer" of medication to ensure the smooth growth of the crop. Noise medical consultation wonderful, sweet music can heal, which has been known to everyone. But how noise can be used for medical consultation it? Recently, scientists have made a laser diagnostic hearing device, which consists of a light source, a noise generator and the computer test three parts. When used, it first by weak short mini-noise generator noise, vibration of the eardrum, and micro-computers will be based on the echo, the data is displayed eardrum function for doctors to diagnose. It tests quickly, will not damage the eardrum, no pain, especially for children. In addition, you can also use noise thermometry to detect human lesions. Active Noise Reduction Measures Three commonly used, namely the sound source at the noise, noise and noise reduction at the human ear, are passive in the communication process. In order to be proactive in eliminating noise, people invented the "Active Noise Control," this technology. Its principle is: All of the sound by a certain spectral composition, if you can find a voice, to eliminate the spectrum and the noise exactly the same, just the opposite phase (a difference of 180 °), the noise can be completely off_set_ these . The key lies in how to get that counteract noise sound. The approach is practical: to proceed from the noise source itself, trying to pass the original electronic circuits reversed phase noise. Seen in this light, Active Noise this technology actually "fire with fire." Noise can inhibit cancer cell growth rate by a German scientist was found in a noisy environment will slow down the growth rate of cancer cells. This discovery may open up a new way for the treatment of cancer. Freiburg School of Medicine, Oncology, Heidelberg, Germany, in cooperation with Music Therapy Research Center successfully carried out preliminary experiments in this area. Scientists in the laboratory dish placed on cultured cancer cells in a micro-speaker sound environment laws found that the growth rate of cancer cells than in normal conditions, 20% slower. In order to verify the reliability of the test, the scientists also no sound through the speaker but only with its magnetic field, another group of cancer cells in the laboratory dish influence, experiments show that the growth rate of cancer in this group did not slow down . Scientists have also found through experiments that can inhibit cancer cell growth rate is not music contains a sense, but "has a certain tone, volume, speed, and acoustic pulse interval common voice." At present, the German scientist also consider the use of large-scale experiments controlled sound stimulation inhibition of tumor cell growth, in order to further validate the reliability and value of this discovery is available. U.S. scientists recently invented a new type of thermometer that can take advantage of the noise temperature measurement. Published in the latest issue of the journal "Science" in this study reported that this instrument can be accurately measured between room temperature and -272.15 degrees Celsius. Researchers at Yale University in the interval with a period of two layers of alumina into aluminum this thermometer. Voltage is applied to the instrument, the electrons generated through the middle compartment, so as to form a current. Voltage relationship between the magnetic field and the amount of noise, or magnetic variation, is based on the current temperature changes. Therefore, if the applied voltage is known, this temperature is called the collection of noise (SNT) of the instrument can measure the temperature. The researchers said, SNT -272.15 degrees Celsius when accurate to a thousandth of accuracy that is now used to measure nearly five times the absolute zero of the thermometer. The biggest advantage of this new design is that it is an original thermometer: the need for external calibration. This is because the relationship between voltage, noise and temperature depend on only the most basic physical constants. Furthermore, the exact temperature range of this instrument is also much larger than the other thermometer. Therefore, the researchers say they developed SNT "than it is now commonly used may have a direct thermometer broader range of uses." Noise impacts on different levels of the human: Intolerable: 150dB ~ 130dB Pain: 130dB ~ 110dB Noisy: 110dB ~ 70dB Quieter: 70dB ~ 50dB Quiet: 50dB ~ 30dB Very quiet: 30dB ~ 10dB Silent: 0d
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Decibel noise standard
★ 10 ~ 20 分贝 almost feel. ★ 20 ~ 40 分贝 equivalent to speak softly. ★ 40 ~ 60 分贝 equivalent room conversation. ★ 60 ~ 70 分贝 detrimental nerves. ★ 70 ~ 90 分贝 noisy. Long-term study and live in this environment, people will gradually damage nerve cells. ★ 90 ~ 100 分贝 cause hearing damage. ★ 100 ~ 120 分贝 people unbearable, a few minutes you can temporarily deafened. Generally about 30 db sound when not affect normal life and rest. And when you reach 50 dB or more, people have a greater sense, it is difficult to fall asleep.
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Wikipedia Encyclopedia
zaosheng wuran Noise Pollution noise pollution Noisy cacophony, a wider scope, the impact was greater.
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English Expression
n.: noise pollution
Related Phrases
Qín huáng dǎo shì city Municipal
notify
administer plan
Containing Phrases
noise pollution level (NPL)
industry noise pollution
Community noise pollution
environment noise pollution
mush Pollution monitoring
noise pollution divination
Noise pollution synthesis prevention and cure
Environment noise pollution Prevention and cure law
Jiangsu Province Environment noise pollution prevention and cure Act
Canton Municipal Environment noise pollution prevention and cure allot
Guangdong province execute The people's republic of china Environment noise pollution prevention and cure plan
Qín huáng dǎo shì city Municipal Environment noise pollution prevention and cure Measures for administration try
the People's Republic of China Environment noise pollution prevention and cure law
The people's republic of china Environmental noise pollution prevention Act
Guangdong province execute The people's republic of china Environment noise pollution prevention and cure plan