Noise pollution

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Noise pollution

Human beings live in a variety of voices. It is impossible to make the surrounding environment absolutely silent. But if the sound is too loud or too noisy, it will cause damage and become something that people don’t need – noise.

銆€銆€Noise is not the sound inherent in nature. It is mainly produced by human activities and living activities.

The source can be roughly divided into two aspects: one is aerodynamic noise, which is the noise caused by the operation of aerodynamic equipment such as a turbine engine; the other is mechanical noise, which occurs when the machine is machined by punching, gear rolling, etc.The noise caused by vibration; the third is the noise generated by the vibration of the iron core caused by the expansion and contraction of the magnetic generator.

The strength of the noise, in decibels as the unit of calculation: 0?
20 decibels are very quiet; 20?
40 decibels are quieter, 40?
60 decibels for general sound, 60?
80 decibels feel noisy; 80?
100 decibels are very noisy; more than 100 decibels are unbearable.

In accordance with international standards, in the downtown area, underground noise should not exceed 55 decibels during the day; 45 decibels at night; general residential areas, no more than 45 decibels during the day and 35 decibels at night.

銆€銆€People may be exposed to noise and may have adverse effects on the body. The main performances are as follows: First, the damage of the sound to the auditory organs: The United States has compared the hearing of tribal residents who have changed the noise interference with the hearing of the town residents.It is found that the hearing of the tribal elderly who are already eighty years old is stronger than that of the 30-year-old urban residents.

This shows that long-term tension and excessive noise stimulation will cause hearing loss, causing the degeneration of the inner ear, which is called noise deafness.

It is generally believed that if a certain type of noise causes a hearing loss of more than 30 decibels, it is dangerous. It is a precursor to pathological changes. Therefore, protective measures should be taken for such noise.

At present, the hearing protection standard of most countries is set at 90 decibels (A). It has been proved that after 40 years of working under this noise standard, the incidence of noise deafness is still around 20%, so the hearing protection standard is increasing.
When people are suddenly exposed to extremely intense noise (such as blasting, shooting, etc.), because of the high sound pressure, often accompanied by shock waves, can cause acute hearing damage, called shock deafness (acoustic trauma).

At this point, the tympanic membrane can be ruptured, bleeding, and both ears are completely inaudible.

銆€銆€In addition to damaging hearing, noise also affects other systems.

The nervous system manifests as a neurasthenic syndrome with headache and sleep disorders, with changes in EEG (alpha rhythm changes, low amplitude, decreased index), autonomic dysfunction, etc.; cardiovascular system is unstable (most increases)), heart rate is accelerated, ECG changes (sinus arrhythmia, graded changes); gastric system secretion decreases, peristalsis slows, appetite decreases; endocrine system manifests as hyperthyroidism, adrenal function, sexual functionDisruption, menstrual disorders, etc.

銆€銆€Second, the impact of noise on sleep: Some people use brain waves as indicators to test the noise interference to sleep, found in 40?
Under the noise of 45 decibels, the brainwaves of sleepers have an awakening reaction.

Explain that strong noise can affect people’s rest and sleep.

銆€銆€In people’s personality, if the noise level is close to the personality, it will interfere with people’s normal personality.

If the noise reaches 90 decibels, it is too loud to scream.

銆€銆€Third, the impact of noise on work: As early as 1932, the impact of noise on the labor efficiency of women workers in textile factories was investigated. It was found that the protection was 1% higher than that of unprotected workers.

Usually the noise is 80 decibels, which reduces the worker’s efficiency.

The reason is that people are irritated and easily tired under the noise interference, causing it to be difficult to concentrate and slow to respond.

銆€銆€In summary, noise must be prevented and controlled, otherwise it will have a great impact on people’s health.

銆€銆€First, control and eliminate noise sources.

The key to solving urban traffic noise pollution is to control the noise of motor vehicles such as cars, motorcycles and tractors.

Taking traffic noise in Beijing as an example, traffic noise is reduced by 5 due to regulations prohibiting cars from honking in non-emergency situations.
10 decibels.

To limit the use of tweeters, it is not allowed to start some machines that are particularly noisy and not easily attenuated at night.

銆€銆€In fact, noise control must be legislated.

In order to protect the environment, national or local authorities have enacted laws and regulations on the control of noise pollution, such as laws, regulations, standards, and orders. Such legislation is mandatory and requires noise pollution to be taken.

In the “Environmental Protection Law of the People’s Republic of China” (Trial) published in 1979, it is pointed out that it is necessary to strengthen the management of urban industrial noise, various noise-producing mechanical equipment, motor vehicles, aircraft, etc., and install noise-cancellation equipment.

Also, it should be speculated to control the propagation of noise.

銆€銆€In the process of noise propagation, measures to attenuate its intensity are mainly distance control, barrier setting, and terrain utilization.

Distance control is to increase the distance between the noise source and the receiver to reduce the degree of noise interference to the recipient.
For example, green belts in residential areas can partially block urban traffic noise from entering residential areas.

Experiments have shown that after 30 millimeters thick bushes, the sound is reduced by 7 decibels by 80 decibels.

In addition, lawns and vegetable gardens also have the effect of reducing noise.

Therefore, urban greening is very important.

When designing and planning residential areas, it is necessary to consider effective measures to prevent noise, such as keeping residential areas away from high-noise factories and continuous traffic streets to prevent factory noise or traffic noise from replacing residential areas.

銆€銆€Finally, it is necessary to strengthen personal protection.

If ear protectors are used, earplugs, soundproof cotton, earmuffs, helmets, etc. are commonly used.
The earplug is an ear protector that is inserted into the external auditory canal and is made of soft rubber or soft plastic.

Its sound insulation, offset is 10?
20 decibels, IF 20?
30 decibels, high frequency 30?
40 decibels.

The so-called soundproof cotton is made with a diameter of 1?
3 micron ultra-fine glass fiber, chemically softened, soft, comfortable and painless, with a high molecular weight of 20?
40 decibels.

The so-called earmuffs are ear protectors that close the entire ear. The high-frequency sound insulation can reach 15?
30 decibels.