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Noise pollution , unwanted or excessive sound that can have deleterious effects on human health, wildlife, and environmental quality. Noise pollution is commonly generated inside many industrial facilities and some other workplaces, but it also comes from highway, railway, and airplane traffic and from outdoor construction activities.
Sound waves are vibrations of air molecules carried from a noise source to the ear. Sound is typically described in terms of the loudness amplitude and the pitch frequency of the wave. Loudness also called sound pressure level, or SPL is measured in logarithmic units called decibels dB.
The normal human ear can detect sounds that range between 0 dB hearing threshold and about dB, with sounds between dB and dB causing pain pain threshold. The ambient SPL in a library is about 35 dB, while that inside a moving bus or subway train is roughly 85 dB; building construction activities can generate SPLs as high as dB at the source.
SPLs decrease with distance from the source. The rate at which sound energy is transmitted, called sound intensity , is proportional to the square of the SPL. Because of the logarithmic nature of the decibel scale, an increase of 10 dB represents a fold increase in sound intensity, an increase of 20 dB represents a fold increase in intensity, a dB increase represents a 1,fold increase in intensity, and so on.
When sound intensity is doubled, on the other hand, the SPL increases by only 3 dB. For example, if a construction drill causes a noise level of about 90 dB, then two identical drills operating side by side will cause a noise level of 93 dB.
On the other hand, when two sounds that differ by more than 15 dB in SPL are combined, the weaker sound is masked or drowned out by the louder sound. For example, if an dB drill is operating next to a dB dozer at a construction site, the combined SPL of those two sources will be measured as 95 dB; the less intense sound from the compressor will not be noticeable.
The human eardrum is a very sensitive organ with a large dynamic range, being able to detect sounds at frequencies as low as 20 Hz a very low pitch up to about 20, Hz a very high pitch. The pitch of a human voice in normal conversation occurs at frequencies between Hz and 2, Hz.
Precise measurement and scientific description of sound levels differ from most subjective human perceptions and opinions about sound. Subjective human responses to noise depend on both pitch and loudness. People with normal hearing generally perceive high-frequency sounds to be louder than low-frequency sounds of the same amplitude. For this reason, electronic sound-level meters used to measure noise levels take into account the variations of perceived loudness with pitch.
Frequency filters in the meters serve to match meter readings with the sensitivity of the human ear and the relative loudness of various sounds. The so-called A-weighted filter, for example, is commonly used for measuring ambient community noise. Noise levels generally vary with time, so noise measurement data are reported as time-averaged values to express overall noise levels.
There are several ways to do this. Another unit, called equivalent sound levels L eq , can be used to express an average SPL over any period of interest, such as an eight-hour workday. L eq is a logarithmic average rather than an arithmetic average, so loud events prevail in the overall result. A unit called day-night sound level DNL or L dn accounts for the fact that people are more sensitive to noise during the night, so a dBA penalty is added to SPL values that are measured between 10 pm and 7 am.
DNL measurements are very useful for describing overall community exposure to aircraft noise, for example. Noise is more than a mere nuisance. At certain levels and durations of exposure, it can cause physical damage to the eardrum and the sensitive hair cells of the inner ear and result in temporary or permanent hearing loss , known as noise-induced hearing loss. Hearing loss does not usually occur at SPLs below 80 dBA eight-hour exposure levels are best kept below 85 dBA , but most people repeatedly exposed to more than dBA will have permanent hearing loss to some extent.
In addition to causing hearing loss, excessive noise exposure can raise blood pressure and pulse rates, cause irritability, anxiety , and mental fatigue, and interfere with sleep , recreation, and personal communication. Children living in areas with high levels of noise pollution may suffer from stress and other problems, such as impairments in memory and attention span.
Noise pollution control is therefore important in the workplace and in the community. Noise pollution also impacts wildlife. A wide range of animals, including insects , frogs , birds , and bats , rely on sound for a variety of reasons. Some of the loudest and most detrimental sounds in the sea are from naval sonar devices, whose noise can travel hundreds of miles through the water and is associated with mass strandings of whales and dolphins.
Noise pollution Article Media Additional Info. Article Contents. Table Of Contents. While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions to improve this article requires login. External Websites. Jerry A. See Article History. Learn about the impact of underwater noise on marine animals, notably harbour porpoises.
Human action has triggered a vast cascade of environmental problems that now threaten the continued ability of both natural and human systems to flourish. Solving the critical environmental problems of global warming, water scarcity, pollution, and biodiversity loss are perhaps the greatest challenges of the 21st century. Will we rise to meet them?
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Atmospheric pollution is not the only type of contamination that is harming living beings on the planet. And according to the European Environment Agency EEA , noise is responsible for 16, premature deaths and more than 72, hospitalisations every year in Europe alone. According to the WHO, noise is harmful when it exceeds 75 decibels dB and feels painful at levels above dB. Drivers honking the horn, groups of workers drilling the road surface, aircraft flying over us in the sky Noise, noise and more noise.
From physiology perspective, always disturb people to rest, the sound that learn and works, namely do not need to voice, all are considered noise. When noise to the people and the surrounding environment adverse effects, the formation of the noise pollution. This paper analyzes the harms and the effects on people, and puts forward prevention and control measures. Request Permissions. Strengthening environmental noise control to improve production and living environment[J]. Chinese environmental management series, Noise pollution in highway construction and its constrol measures[J].
Noise pollution , unwanted or excessive sound that can have deleterious effects on human health, wildlife, and environmental quality. Noise pollution is commonly generated inside many industrial facilities and some other workplaces, but it also comes from highway, railway, and airplane traffic and from outdoor construction activities. Sound waves are vibrations of air molecules carried from a noise source to the ear.
Noise pollution has been recognized as one of the major hazard that impacts the quality of life all around the world. Because of the rapid increase in technology, industrialization, urbanization and other communication and transport systems, noise pollution has reached to a disturbing level over the years which needs to be studied and controlled to avoid different health effects like high blood pressure, sleeplessness, nausea, heart attack, depression, dizziness, headache, and induced hearing loss. To address this situation, different countries have different strategies like vehicular noise limits and their regulation, vehicles physical health checkup, different time of operations for noisy traffic like trucks in the evening or night time, and noise pollution fines for noisy vehicles. Autonomous Vehicle and Smart Traffic. A sound is termed as noise when it becomes continuous and above the threshold limits of the ears [ 1 ].
Конечно же, это убийца! - закричал Бринкерхофф. - Что еще это может. Иначе Танкадо не отдал бы ключ. Какой идиот станет делать на кольце надпись из произвольных букв. Фонтейн свирепым взглядом заставил его замолчать. - Вы меня слышите? - вмешался Беккер, чувствуя себя неловко. - Вы все время говорите о произвольном наборе букв.
Они работали .
Но у него не выдержали нервы. Он слишком долго говорил ей полуправду: просто есть вещи, о которых она ничего не знала, и он молил Бога, чтобы не узнала. - Прости меня, - сказал он, стараясь говорить как можно мягче.
Только если файл не заражен вирусом. Бринкерхофф даже подпрыгнул. - Вирус.
В сердцах он швырнул трубку на рычаг. - Черт! - Фонтейн снова схватил трубку и набрал номер мобильника Стратмора. На этот раз послышались длинные гудки.
Может быть, ключ связан с количеством человеческих жертв, оценочной суммой нанесенного ущерба в долларах… - Она замолчала, снова вчитываясь в текст.
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