Noise refers to the sound produced by the vocal body when it vibrates irregularly. Sound is produced by the vibration of an object and propagates in the form of waves in a certain medium, such as solid, liquid and gas. Noise pollution is usually referred to as man-made. From a physiological point of view, any sound that interferes with people's rest, study and work, and interferes with the sound you want to hear, that is, unnecessary sound, collectively known as noise. Noise pollution occurs when noise causes adverse effects on people and the surrounding environment. Since the industrial revolution, the creation and use of various mechanical equipment has brought prosperity and progress to mankind, but at the same time, it has also produced more and more noise. Noise can not only cause hearing damage, but also induce a variety of carcinogenic and fatal diseases, and also interfere with people's life and work.
(1) Traffic noise includes the noise of motor vehicles, ships, metros, trains, aircraft and so on. Because of the rapid increase in the number of motor vehicles, traffic noise has become the main noise source in the city.
(2) Noise generated by various equipment in industrial noise factories. Industrial noise generally has a higher sound level, which has a greater impact on workers and the surrounding residents.
(3) The noise of building mainly comes from the noise of construction machinery. The characteristic of building noise is that its intensity is high, and it mostly occurs in densely populated areas, so it seriously affects the rest and life of residents.
(4) Social noise includes people's social activities and noise from household appliances and audio equipment. Although the noise level of these equipment is not high, because of the close connection with people's daily life, people can not get quiet during rest, which is particularly annoying and easy to cause neighborhood disputes.
In order to reduce the impact of noise on the surrounding environment and human beings, the main noise control methods isolate or protect the noise source, the noise propagation path and the receiver, and block or absorb the energy of noise. For example, noise sources (motors) are equipped with shock-proof springs or rubber to absorb vibration or cover the whole motor. Generally speaking, sound insulation wall is used to block the propagation of noise. For the protection of the receiver, it is usually sound-proof windows, earplugs and so on.
Governments around the world usually have laws or regulations to control excessive noise.
Noise pollution is harmful to people, animals, instruments and buildings. The degree of its harm depends mainly on the frequency, intensity and exposure time of noise. Noise hazards mainly include:
Noise damage to hearing
The most direct harm of noise to human body is hearing loss. When people enter a noisy environment, they will feel uncomfortable in both ears and even have headaches after exposure for a period of time. After a period of rest from the noisy environment to a quiet place, the hearing will gradually return to normal. This phenomenon is called temporary threshold shift, also known as hearing fatigue. However, if people work in strong noise environment for a long time, hearing fatigue can not be recovered in time, and organic lesions will occur in inner ear organs, that is, permanent threshold deviation, also known as noise deafness. If a person is suddenly exposed to extremely strong noise environment, the auditory organs will suffer from acute trauma, which will lead to rupture of the tympanic membrane, bleeding, labyrinth bleeding, and acute peeling of spiral organs from the basement membrane, which may lead to complete hearing loss, i.e. violent deafness.
If you work in a strong noise environment for a long time without protection, the recovery of auditory sensitivity will be prolonged after leaving the noise environment. After several hours or more, the hearing can be restored. This loss of hearing that can be restored is called hearing fatigue. With the aggravation of auditory fatigue, hearing impairment will occur. Therefore, to prevent noise deafness, fatigue should be prevented first. Normally, noise below 85 decibels is not harmful to hearing, while noise above 85 decibels may be dangerous. Statistics showed that the incidence of deafness increased significantly in the noise environment of over 90 dB for a long time.
Noise can induce many diseases
Because noise acts on the central nervous system of the brain through auditory organs, so it affects all organs of the whole body, so noise can not only cause damage to human hearing, but also bring harm to other systems of the human body. Because of the effect of noise, it can produce headache, brain swelling, tinnitus, insomnia, general fatigue and weak memory and other symptoms of neurasthenia. The incidence of hypertension, atherosclerosis and coronary heart disease is 2-3 times higher in long-term workers working in high noise environment than in low noise environment. It can be seen that noise can lead to cardiovascular diseases. Noise can also cause dyspepsia, loss of appetite, nausea and vomiting, and increase the incidence of gastrointestinal diseases and ulcers. In addition, noise also has some effects on visual organs, endocrine function and normal fetal development. The general health level of people working and living in high noise decreases year by year, and their resistance to diseases decreases, which leads to some diseases. However, it is also related to individual physical factors, which can not be generalized.
Disturbance of life and work
Noise has a great influence on people's sleep. Even in sleep, people's hearing must be stimulated by noise. Noise can lead to multiple dreams, easily wake up, sleep quality decline and so on. Sudden noise has a more prominent impact on sleep. Noise can interfere with people's conversation, work and study. Experiments show that when a person is disturbed by a sudden noise, he loses four seconds of concentration. According to statistics, noise can reduce labor productivity by 10-50%. With the increase of noise, the error rate increases. Thus, noise can disperse people.