The scientific definition of noise is noise. From the physiological point of view, all the voices that interfere with people's rest, study and work, as well as the voices that interfere with people's listening, that is, unwanted voices, are collectively referred to as noise.When the noise affects people andsurrounding environmentWhen adverse effects are causednoise pollution。
In physics, noise refers to all irregular signals (not necessarily sound), such as electromagnetic noise,thermal noise, noise during radio transmission, laser noise, optical fiber communication noise, image noise when camera takes pictures, etc.[1]
Chinese name
noise[1]
Foreign name
noise
Alias
Noise
Definition
A kind of sound that causes people to be agitated, or the sound volume is too strong and is harmful to human health
Class I causes people to be agitated, or the volume is too strong to be harmfulhuman health 's voice[1]。
Noise not only affects hearing, but also affects people'scardiovascular system, nervous systemendocrine systemIt has adverse effects, so some people call noise "chronic poison that can kill people".[2]
Noise is a kind ofsubjectiveEvaluation criteria, that is, all voices that affect others are noise, even music.[1]
From the perspective of environmental protection, all "unwanted sounds" that affect people's normal study, work and rest in some occasions are collectively referred to as noise.Such as machineburningSound, the whistling of various vehicles, the noise of people and various sudden sounds are all called noise.[1]With the development of industrial production, transportation, urban buildings, and the increase of population density, family facilities（TelevisionWith the increase of environmental noise, it has become a major public hazard that pollutes the human social environment.[3]
From a physical point of view, noise is irregularMechanical wave。[1]
Class 0 standard is applicable to sanatorium area, senior villa area, senior hotel area and other areas that need special peace.Such areas located in suburban areas and rural areas shall be subject to 5 decibels stricter than Class 0 standards respectively.[7]
two
Class 1 standards are applicable to the areas dominated by residential, cultural and educational institutions.The rural residential environment can refer to these standards.[8]
three
Class 2 standards are applicable to residential, commercial and industrial mixed zone.[9]
four
Class 3 standards apply to industrial areas.[10]
five
The Class 4 standard is applicable to the areas on both sides of trunk roads in urban roads and inland waterways crossing urban areas.The background noise (refers to the noise level when the train does not pass) limits of the areas on both sides of the main and secondary trunk lines of the railway passing through the urban area shall also comply with this standard.[11]
Sudden noise at night
MaximumDo not exceed the standard value by 15 decibels.[6]
Industrial enterprise standards
Applicable scope of the standard
This standard is applicable to factories and those that may cause noise pollutionenterprises and institutionsBoundary of[7]
Standard value
The standard values of various plant boundary noise are as follows:
Category Daytime Night
Class I 55dB 45dB
Class II 60dB 50dB
Category III 65dB 55dB
Class IV 70dB 55dB
Delimitation of application scope of various standards(The scope of application of various standards shall be determined by the local people's government)
one
Class I standards are applicable to the areas dominated by residential, cultural and educational institutions.[14]
two
Class II standard is applicable to residential, commercial, industrial mixed zone and commercial center.[15]
three
Class III standards are applicable to industrial areas.[16]
four
Class IV standards are applicable to areas on both sides of trunk roads.[17]
Noises at night
The peak value of noise (such as exhaust noise) that frequently breaks out at night shall not exceed the standard value by 10 dB
The peak value of occasional sudden noise at night (such as short whistle sound) shall not exceed the standard value by 15 decibels.
Relevant standards
one
In China, relevant standards stipulate that the noise in residential areas shall not exceed 55 decibels in the daytime and shall be lower than 45 decibels at night.
two
In order to prevent noise, Professor Ma Dayou, a famous Chinese acoustician, summarized and studied the hazards and standards of various kinds of noise at home and abroad, and put forward three suggestions:
① In order to protect people's hearing and health, noiseAllowable valueAt 75-90 decibels.
② Ensure conversation and communication, and the allowable value of environmental noise is 45~60 decibels.
③ ForSleep timeIt is recommended to be 35~50 decibels.
Supplement:
① 30-40 decibels is an ideal quiet environment.
② 70 decibels will affect the conversation.
③ If you live in an environment above 90 decibels for a long time, your hearing will be seriously affected andNeurasthenia, headachehypertensionAnd other diseases.
④ If suddenly exposed to noise up to 150 dBTympanic membraneIt will rupture and bleed, and both ears will lose hearing completely;Severe cases can lead to heart disease and death.[8]
Wide band noise (fromshortwavereachlong waveRelatively uniform noise), narrow band noise (the main components are concentrated in narrowwavelengthNoise within the range), modulated noise (existing continuouswavelength, but also discretewavelengthComponent).[1]
By urban noise category
traffic noise
It mainly refers to vehicles such as motor vehicles, aircraft, trains and shipsRuntimeNoise emitted.Of these noisesnoise sourceIt is mobile and has a large interference range.
Industrial noise
Mainly refers to industryproductive laborNoise generated in.Mainly from machines and high-speed running equipment.
Construction noise
Mainly refers to buildingsConstruction siteNoise generated.In construction, a large number ofPower machineryIt is necessary to excavate, drill holes, mix, and frequently transport materials and components, thus generating a lot of noise.
4. Decoration, crane, elevator, etc. shall not exceed 65 dB in daytime and 55 dB at night
Social noise
It mainly refers to people's activities in commercial transactions, sports competitions, parades, gatherings, entertainment places, etcsocial activitiesThe noise generated by, andrecorder, TV, washing machine and other household appliances, such noise is generally below 80 decibels.For example, the noise of washing machines and sewing machines is 50-80 decibels,electric fanThe noise is 30-65 decibels, and that of air conditioners and televisions is 70 decibels.
Engine noise
Engine noiseIt mainly includes combustion noiseMechanical noise, advanceexhaust noise 、cooling fanAnd other components.According to the mechanism of engine surface noise, it can be divided into combustion noise and mechanical noise.
(1) Combustion noise
The combustion noise is caused by the flame in the cylindergas pressure Sharp rise impacts all parts of the engine to make it emitMechanical waveThe noise generated by.In dieselCetane numberImproper or too early fuel injection time will cause the engine to work furiously and make the noise increase sharply.gasoline engineDue to overheating, poor gasoline quality andIgnition advance angleToo large and other reasonslong waveCombustion sound,Knock cylinderPhenomenon, etc.
(2) Mechanical noise
Mechanical noise is generated by the combustion process and structure inside the engineMechanical waveThe noise is generated by the engineOuter surfaceAnd external surface of engineRigid connectionStructural orientationAtmospheric radiationTherefore, it is called engine surface noise.
noise control
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adequatenoise control, must considernoise sourceThe whole system composed of noise transmission path and noise receiver.
Although the technology of noise control is maturemodern industry、communications and transportation industryThe scale is very large, and there are many enterprises and places that need to adopt noise control. Therefore, in terms of preventing noise, we must make a comprehensive balance from the aspects of technology, economy and effect.Of course, specific issues shouldmake a concrete analysis。The noise intensity shall be low outside the control room, design room, workshop or the place where the staff work for a long time;Few people go to workshops or open places in the warehouse, so it is OK to have a little higher noise.In short, there should be some differences in the treatment of noise at different times, places, natures and durations.
In buildings, measures taken to reduce noise are mainly sound insulation and 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.For multi-layer dense materials in buildingsporous material SeparatedSandwich structureIt will also have a good sound insulation effect.In order to eliminate noise, commonly usedSound absorbing materialMainlyPorous sound-absorbing material, such asGlass wool、Mineral wool、Expanded perlite, PerforationSound-absorbing boardEtc.The sound absorption performance of a material depends on itsfriction, flexibility, porosity and other factors.In addition, the lawns and trees around the buildings are also good sound absorption materials, so planting flowers and trees not only beautifies the living and learning environment, but also prevents noise from polluting the environment.
Blocking noise propagation
Reduce noise in the way of noise transmission,Control noiseTo change the noise already emitted by the sound sourceRoute of transmission, such as adopting noise absorption, noise barrier and other measures, and reasonably planning the urban and architectural layout.
Take measures against noise
The noise protection of the noise recipient or noise organ cannot take measures on the sound source and transmission path, or the acoustic measures taken still cannot reachanticipate resultIt is necessary to takeProtective measuresFor example, workers exposed to long-term occupational noise can wear earplugsEarmuffOr helmet, etcEar protector。
harm
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Interference with rest and sleep
Rest and sleep are for people to eliminate fatigue, restore physical strength and maintain healthnecessary condition。However, noise makes people restless and difficult to rest and sleep.When people can't fall asleep after tossing and turning, they will feel nervous,Shortness of breathThe pulse will beat faster and the brain will be more excited, and you will feel tired or weak the next day.So as to affect work and study, as time goes byNeurastheniaSymptoms, manifested as insomniatinnitus, fatigue.After people go to sleep, even if it is 40-50 decibels lighternoise interference , will also change from a deep sleep to a semi deep sleep.When people are asleep, their brain activity is slow and regular, and they can get full rest;While in the state of semi deep sleep, the brain is still in a tense and active stage, which will make people unable to get sufficient rest and physical recovery.
Reduce work efficiency
The study found that noise above 85 decibels will make people feel upset, and people will feel noisy, so they can't concentrate on their work, which will result inwork efficiencyLower.
Auditory fatigue
Having such experience, getting off the plane or fromForging workshopCome out, you can't hear the voice of the other side clearly, and it will recover after a while.This phenomenon is calledAuditory fatigue, is the human bodyorgan of hearingA protective response to the external environment.
Hearing loss
If people are exposed to strong noise for a long time, their hearing will be weakened, which will lead toOrganic damage, causingHearing loss。
Cardiovascular damage
Noise isCardiovascular diseaseNoise will accelerate heart aging and increasemyocardial infarctionmorbidity.Medical expertsAnimal experimentIt is proved that long-term exposure to noise canadrenal glandThe increase of secretion will increase the blood pressure. People who live in the noise of 70 decibels on average for a long time can increase the incidence of myocardial infarction by about 30%, especially at night.The survey found that living inexpresswayThe myocardial infarction rate of nearby residents increased by about 30%.1101 women textile workers were investigated,hypertensionThe incidence rate was 7.2%, of whichContact strengthThe incidence of hypertension was 15.2% when the noise reached 100 decibels.
Cause ear discomfort
Such as tinnitus, earache, hearing loss
It is determined that noise exceeding 115 dB will also causedeaf。according toclinical medicineAccording to statistics, if people live in a noise environment of more than 80 decibels, 50% of them will be deaf.Medical experts believe that family noise is caused by childrendeaf-muteOne of the causes of the disease.Noise is more harmful to children's physical and mental health.Because the children are not mature, noise can damage the hearing organs, whether it is the fetus in the body or the newborn childHearing lossOr lost.According to statistics, there are more than 70 million deaf people in the world today, most of whom are caused by noise.Expert research has proved that indoor noise is the main reason for children's deafness. If they live in noise above 85 decibels, the deaf can reach 5%.
be bad for eyes
People only know that noise affects hearing. In fact, noise also affects brain nerve metabolism, and thenIndirect impactvision.The experiment shows that when the noise intensity reaches 90 decibels, human visual cellssusceptibilityDescend, identify weak lightreaction timeExtension;When the noise reaches 95 decibels, 40% of the peoplePupillary enlargement, blurred vision;When the noise reaches 115 decibels, most people's eyesLuminanceThe adaptation of.So people who have been in the noise environment for a long time are easy to happenEyestrainEye injuries, such as eye pain, blurred eyes and tears.At the same time, noise will also makeColor visionThe visual field is abnormal.Noise found in investigationPara red, blue and whiteReduced vision80%。
Damage nerves
If the noise acts on people for a long timecentral nervous system, can makeCerebral cortexExcitation and inhibition disorders, abnormal conditioned reflexdizzy、headache, tinnitusabnormal sweating, insomnia, panicMemory loss, inattention and other symptoms, which can occur in serious casesInsanity。The curative effect of drug treatment for this symptom is poor, but when the noise environment is removed, the symptom will be significantly improved.
Noise also has an impact on human endocrine function, such as: leading to female sexual dysfunction, menstrual disorders, abortion, premature birth rate increase.Noise not only affects womenNoise deafnessAnd has adverse effects on menstruation and fertility of women.In addition, it may lead to abortion, premature delivery, or evenTeratology。Foreign countries have investigated the prevalence of miscarriage and premature delivery among pregnant women in a certain area, and found that they live around an airport. The culprit is the strong noise generated by the huge energy of the aircraft that flies and lands.
Unfavorable development
According to the survey, children live in a noise environment of 75 decibelsFunctional developmentThey will be damaged to varying degrees. Children living in noise environment have 20% lower intellectual development than children living in quiet conditions.
Because children are not yet mature, noise can damage the hearing organs and cause hearing loss, whether it is a fetus in the body or a newborn child.According to statistics, there are more than 70 million deaf people in the world today, most of whom are caused by noise.Expert research has proved that indoor noise is the main reason for children's deafness. If they live in noise above 85 decibels, the deaf can reach 5%.
Influence people's psychology
The psychological impact of noise on people is mainly to make people upset, excited, irritable, and even lose their sense.
Noise is harmful to animals and buildingsplant growth Bad, some even died.
Noise may causenervous systemDysfunctionMental disorders、Endocrine disordereven to the extent thatAccident raterise.The high noise working environment may cause dizziness, headache, insomnia, dreaminessGeneral fatigue, memory loss, fear, irritability, inferiority and even insanity.In Japan, there have been cases of insanity and suicide due to unbearable train noise.
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Traffic noise
The increasingly developed urban transportation industry has brought convenience and comfort to people's work and life, and also promoted the economic development.However, we can't help but see that with the increase of urban and rural vehicles and the increase of highway and railway trunk lines, the noise of locomotives and motor vehicles has becometraffic noise The culprit ofcity noise75%.Statistics show that Beijing is a world famous city with noise pollution.Although the urban vehicles are less than one tenth of those in Japan, the noise level is twice as high as that in Japan.In particular, some buildings facing the street suffered a lot.
Industrial machinery noise
This is also indoornoise pollutionThe main source of.Due to variousPower machine、Working machineThe combustion, impact, friction and jet generated during work can produce sound above 70 or 80 decibels.Textile workshop, forging workshop, crushing workshop and steel plant, cement plant, air pump room and water pump room are all serious. Although noise reduction treatment has been done to a certain extent, the noise generated by the machine body cannot be fundamentally eliminated.
Urban building noise
From 2010 to 2013, urban construction developed rapidly, including road construction, infrastructure construction, urban building developmentOld city reconstruction, as well as the interior decoration of common people's families, which has caused urban building noiseConstruction siteThe noise is generally above 90 decibels, up to 130 decibels.
Social noise
For example, commercial noise in public places, restaurants, busesPassenger train, crowd gatherings, etc.According to statistics,civil lifeAnd public places accounted for 14.4% of urban noise.
noise pollution
With the development of people's life modernization, the noise of household appliances in the family is more and more harmful to people.
According to the test, TVrecorderThe noise generated can reach 60 to 80 decibels, 42 to 70 decibels for washing machines and 34 to 50 decibels for refrigerators.
Family karaoke machines are widely popular. Some people are indulged in enjoyment regardless of others' happiness, which adds noisePollution intensity。
