Here is a compilation of notes on Noise Pollution. After reading these notes you will learn about: 1. Meaning of Noise Pollution 2. Adverse Effects of Noise Pollution 3. Control.
Note # 1. Meaning of Noise Pollution:
Noise pollution is a type of energy pollution in which distracting, irritating or damaging sounds are freely audible. Noise is an important environmental pollutant like noxious gases that befoul our air, water and soil. It destroys bridges and produces cracks in buildings. The noise can cause skin and mental diseases.
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The various ranges and sources of sound pollution are given in Fig. 1.
Whether knowingly or unknowingly, every-one of us contributes to noise pollution, because most of our day-to-day activities generate some noise. Often neglected, noise pollution adversely affects the human beings leading to irritation, loss of concentration, loss of hearing. Noise pollution is an effective slow poison.
In every city of the world, the early morning tranquility is shattered by the shrill pressure horns of vehicles like trucks, buses, scooters, motor cycles, the drivers always pressing the horns more out of habit than necessity. About the same time, loudspeakers take to the air from a top religious places calling on the faithful’s to arise and pray to the Almighty.
On a special day like festivals, marriage functions, birthday parties etc., we can hear loudspeakers drilling the common man with severe noise pollution.
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As the city gradually awakens all kinds of noise pollutants take to the air. Traffic picks up. Factories in residential areas start operations. Radios and transistors blare out the AIR mileau. Motor workshops in the midst of localities start dent beating and hammering. The sources of noise may vary according to day to day activities.
These sources may be domestic (movement of utensils, cutting and peeling of fruits/vegetables etc.) natural (sea-shores, birds/animals shouts, wind movement, sea tide movement, waterfalls etc.), commercial (vendor shouts, authomobiles, aeroplanes, marriages, laboratory, machinery etc.) industrial (generator sets, boilers, plant operations, trolley movement, transport vehicles, pumps, motors etc.).
The noise levels of some of the sources are summarised in table 1.
As the day rises, the noise level in different parts of the city increases-in and around work places and homes. The peak noise levels are reached in the twilight hours as traffic reaches a peak. Marriage processions, TVS add to the confusion. In offices also there is noise pollution due to clicking of typewriters, bells, ringing telephones, clattering office machines and conversations.
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They produce tantrums, headache, fatigue and even nausea. On road you have noise pollution due to growling automobiles, squealing tyres, screeching brakes, screaming sirens, blaring tellys, and radios, blasting horns, whining jets and pounding jackhammers.
Add to these non-metabolic sounds, loud mouths and noisy gaits to make the island specifically Indian! The deafening din is no longer the monopoly of battlefields—our cities have quite matured and boom cacophonous noises as naturally as they do babies. There is a constant background roar; punctuated by strident outbursts of many kinds and even the nights remain awoke to an undefinable moaning sound.
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Typical surveys pertaining to causes of noise pollution reveal the various sources of noise pollution and frequency variation of their occurrence. The results of a survey conducted in Central London, way back in 1961-62 reveals the presence of noise pollution even in the early ’60s (Table 2). Road traffic is identified as the major source of noise pollution while at home or outdoors or at work.
The variations in the emission of noise level in a particular environment can be assessed from the statistical distribution of noise level in that environment (Fig. 1). To draw a statistical distribution curve, terms like L10, L 50 and L 90 play an important role.
The sound level exceeding 10%, 50% and 90% of the total time interval during a particular period is designated as L10, L50 and L90, respectively.
From figure 1, it can be seen that, 90% of the sound levels are about 64 dB (A). Local disturbances increase the sound levels (L10) to 76 dB (A), i. e., during 10% of the total time L90 represents the background noise level.
The equivalent noise level, can also be calculated as
Leq = L50 + (L10 – L90)2/60
Noise Climate (NC):
It is the range over which the sound levels are fluctuating in an interval of time
NC = L10 – L90 dB/sampling time.
Hence, Leq in the above example is:
Leq = 69 + (76- 64)2/60 = 71.4 dB. and noise climate, NC = 76 – 64 = 12 dB/sampling time.
It is nothing short of irony that most of our solutions need further solution because of the problem generating tendency of our problem solving process.
A survey by the U.S. Federal Council of Science and Technology has revealed that noise is a technology generated problem and that the overall loudness of environmental noise doubles over ten years in pace with our social and industrial progress. This geometric progression wise growth of noise could be mind-boggling in view of the ever increasing pace of technological growth.
According to Robert Koch a Nobel Prize winner German bacteriologist. “A day will come when man will have to fight merciless noise as the worst enemy of health.” According to him “Noise like smog, is a slow agent of death.” If it continues for the next 30 years as it has for the past 30 years, it could become lethal.
Note # 2. Adverse Effects of Noise Pollution:
Noise could effect adversely the human beings, environment and animals in many ways.
Some of the adverse effects of noise are:
Effects on Human beings:
Noise pollution effects on human health is a matter of great concern, the reason being the adverse consequences that high noise levels have on human health.
Noise pollution can affect us in several ways, some of which are listed below:
(i) Hearing Problems:
Exposure to noise can damage one of the most vital organs of the body, the ear. Hearing impairment due to noise pollution can either be temporary or permanent. When the sound level crosses the 70dB mark, it becomes noise for the ear.
Noise levels above 80 decibel produce damaging effects to the ear. When ear is exposed to extreme loud noise (above 100 decibel) for a considerable period of time, it can cause irreparable damage and may lead to permanent hearing loss.
(ii) Cardiovascular Issues:
A noisy environment can be a source of heart related problems. Studies have shown that high intensity sound causes a dramatic rise in blood pressure as noise levels constrict the arteries, disrupting the blood flow. The heart rate (the number of heart-beats per minute) also increases. These sudden abnormal changes in the blood increase the likelihood of cardiovascular diseases in the long run.
(iii) Sleep Disturbance:
This is one of the noise pollution effects that can deter your overall well-being. Noise can interrupt a good night’s sleep, and when this occurs, the person feels extremely annoyed and uncomfortable. People deprived of uninterrupted sleep show a sharp dip in their energy levels which often results into extreme fatigue. This can considerably decrease a person’s ability to work efficiently.
(iv) Interference in Verbal Communication:
A noisy environment that produces more than 50-60 decibel simply does not allow 2 people to communicate properly. Interpreting the speech of a second person becomes quite difficult and may lead to misunderstanding.
Effects of Noise Pollution on Physical Health:
The most direct harmful effect of excessive noise is physical damage to the ear and the temporary or permanent hearing loss often called as ‘temporary threshold shift’ (TIS). People suffering from this ailment are unable to detect weak sounds.
However, hearing ability is usually recovered within a month of exposure. In Maharashtra, people living in close vicinity of Ganesh mandals that play blaring music for ten days of the Ganesh festival are usually known to suffer from this dilema.
Permanent loss, usually called ‘noise-induced permanent threshold shift’ (NIPTS) represents a loss of hearing ability from which there is no recovery.
Below a sound level of 80 dB hearing loss does not occur at all. However, temporary effects are noticed at sound levels between 80 and 130 dB. About 50% of the people exposed to 95 dB sound level at work will develop NIPTS and most people exposed to more than 105 dB will experience permanent hearing loss to some degree. A sound level of 150 dB or more can physically rupture the human eardrum.
The degree of hearing loss depends on the duration as well as the intensity of the noise. For example, 1 hour of exposure to a 100 dB sound level can produce a TIS that may last for about one day. However, in factories with noisy machinery, workers are subjected to high sound levels for several hours a day.
Exposure to 95 dB for 8 hours every-day for over a period of 10 years may cause about 15 dB of NIPTS. In addition to hearing loss, excessive sound levels can cause harmful effects on the circulatory system by raising blood pressure and altering pulse rate.
Effects of Noise Pollution on Mental Health:
Noise can also cause emotional or psychological effects such as irritability, anxiety and stress. Lack of concentration and mental fatigue are significant health effects of noise. It has been observed that the performance of school children is poor in comprehension tasks when schools are situated in busy areas of a city and suffer from noise pollution.
As noise interferes with normal auditory communication, it may mask auditory warning signals and hence increase the rate of accidents especially in industries. It can also lead to lower worker efficiency and productivity and higher accident rate on the job.
Thus, noise is just more than a mere nuisance or annoyance. It definitely affects the quality of life. It is, therefore, important to ensure the mitigation or control of noise pollution.
Effects on Animals:
Man-made noise pollution has made the earth an uncomfortable place to live for animals as well. Hearing loss and rapid increase in heart rate are some of the ill-effects of noise pollution on animals. High intensity sound induces fear, forcing them to abandon their habitat.
Other effects of noise on animals are given below:
i. Anxious behaviour in animals is commonly observed in the form of trembling when they are exposed to high decibel levels. Intolerable noise levels can decrease a cow’s capacity of milk production. These animals require a calm and relaxed environment to provide better milk yield.
ii. Research has proved that aircraft induced noise is responsible for a significant decrease in reproduction activity in a wide range of animals. Noise pollution effects can also be seen on chicken in the form of a sharp drop in egg production. Stunted growth in chickens due to intense noise has also been observed.
iii. Underwater animals such as whales and dolphins too experience discomfort due to noise pollution caused by submarines, shipping companies, and sonars.
iv. Birds in urban areas, that use their sharp hearing abilities to hunt prey, are at a loss due to intervention of man-made noise. High noise levels can also negatively affect the breeding and feeding patterns of some animals. This is one of the reasons why certain species have become extinct.
v. Sea animals produce varying sound levels among each other. However, the noise of commercial ships does not allow these animals to communicate properly, which can wreck havoc on their reproductive function. Sonar navy tests can hurt the whale’s ear and reduce its ability to breed and feed.
Effects of Noise on Industrial Workers:
Industrial noise adversely affects the workers and they suffer from various health problems. High volume of sound leads to increased adrenaline (harmone) levels, which leads to the constriction of blood vessels, which normally happens when the individual is tensed, afraid, anxious or extremely happy and excited.
The work pressure and the noise pollution both lead to a fairly typical situation, which leads to clinical as well as psychological stress. The blood pressure, due to the (constriction of blood vessels) vasoconstriction, remains high for the major part of the day.
The human dislike towards anything that is not pleasant, yet compelling leads to emotional stress and depression which is a severe situation. Statistically there is a rise in the number of workers dying of cardiac arrests and cerebral attacks is on an increase considerably due to industrial noise pollution in railway yards, factories etc.
Some people also suffer from headache, which decreases their efficiency level and hamper the quality of their work. That leads to crisis in workplace as well as at home. Workers are always agitated and excited that result into carelessness.
Workers also become fatigued and in some cases over fatigued. The worst part of Industrial Noise pollution is that it affects the unborn baby in a womb and that too in the early days after conception since the faetus is sensitive to sounds. The high decibels affect the growth of its organs.
The problems that the Industrial workers face are sleep disorders and behavioural changes. They experience increased level of stress. They fail to achieve harmony thus leading to a lot of minor psychological problems, which are too common to be noticed. They are irritated and annoyed; therefore fail to interact with a person around them and this leads them to become “loners”.
They withdraw from the society and some in extreme circumstances might have “tremors”, speech problems and many other behavioral problems. It is high time that the rules and regulations that already exist should be applied and followed so that we can cope with the ever increasing problem of noise pollution that is concentrated in the industry environment.
Note # 3. Control of Noise Pollution:
Due to the various adverse impacts of noise on human beings and environment, noise should be controlled. The control of noise pollution depends upon the extent to which noise reduction is required, nature of equipment used and the economy aspects of the available techniques.
There are four fundamentals ways in which noise can be controlled:
(i) Reduce noise at the source
(ii) Block the path of the noise
(iii) Increase the path length of noise and
(iv) Protect the recipient. In general the best control method is to reduce the noise level at source.
(i) Reducing the Noise level from Domestic Sector:
The domestic noise comes from radios, tape recorders, television sets, mixers, washing machines, cooking operations. The noise from the television sets, tape recorders & radios can be controlled if they are played “in low” volume.
The noise from mixers, washing machines & from cooking can be minimised by their selective and judicious operation for required time. The noise generated from falling of items in house can be minimised by the use of carpets.
(ii) Automobile Servicing (Fixing of silencers):
Automobiles account to the highest production of noise. Regular servicing and tuning of vehicles will reduce the noise level.
i. Control over vibrations:
The vibrations of materials may be controlled using proper foundations, rubber padding etc. to reduce the noise level caused by vibrations.
ii. Low voice speaking:
Speaking at a voice enough for communication reduces the excess noise levels.
iii. Loud speaker prohibition:
By not permitting the usage of loudspeakers in residential zones except for important meetings. Now-a-days, the urban Administration of the metro cities in India is becoming stringent on usage of loudspeakers.
iv. Machine quality:
Selection of machinery or equipment’s which generate less noise (sound) due to superior technology etc. is also an important factor in noise minimisation strategy.
v. Maintenance of machines:
Proper lubrication and maintenance of machines, vehicles etc. will reduce noise level.
vi. White noise machine:
The latest technology for overcoming the effects of noise is using white noise machine. It is a device which converts unbearable noise into pleasant sound. This machine is placed between the source of noise and the receptor & it produces soft sound like that of water fall, fan and soft music.
(iii) Control in the Transmission Path:
The change in the transmission path will increase the distance of travel for the wave and sound on such a long path will get absorbed/ refracted/radiated in the surrounding environment. The following techniques can be used for transmission of path.
(iv) Installation of Barriers:
For a barrier to be effective, its width should be more than the height (Fig. 5). The X-axis represents the centre frequencies of the octave band. The barrier should be close to the source i. e., R << D to increase the traversed length for the sound wave because (when D >> R) the presence of the barrier becomes less effective because of the possibility of refractive atmospheric effects.
(v) Green Belt Development:
Growing trees or green plants for reduction or attenuation of sound is called green belt development. The degree of attenuation varies with species of green belt. The reduction of noise levels by shrubs and trees can be presented as Fig. 6 (a) and (b).
Suggestions:
(1) It is the job of voluntary bodies to create awareness of noise pollution and create a consciousness for hearing a quieter environment.
(2) It is the duty of local authorities to curb the use of loud speakers for social and religious purposes, shift the factories and motor workshops from residential areas to create a proper environment for people to live in.
(3) The policeman’s pit should contain a sound meter to enable him to bring the offenders to book.
(4) There are various techniques to control the noise in industrial areas. They should be adopted.