Sources of noise are numerous but may be broadly classified into two classes such as :
The industrial may include noises from various industries operating in cities like transportation, vehicular movements such as car, motor, truck, train, tempo, motor cycle, aircrafts, rockets, defence equipments, explosions etc.
The disturbing qualities of noise emitted by industrial premises are generally its loudness, its distinguishing features such as tonal or impulsive components, and its intermittency and duration.
Among the non-industrial sources, important ones are as follows:
In India, one of the very common man made source of noise pollution has been the frequent use of loudspeaker. For every occasion, religious, or non-religious, public or private, presence of loudspeaker has been a must, as if it has been one of the paraphernalia. The most shocking example of the use of loudspeaker is the one made for religious purposes. Most people bear it and are reluctant to lodge a complaint for the fear of unpleasant neighbourhood relations and fear.
It is torturous for a person who wants to rest or sleep. It has been observed on certain occasions that continuous use of loudspeakers create disturbances to the students during examination periods. Their use adds to the agony of patients. Loudspeakers are also blaring loud noise from morning to dead to night for advertisement purposes by various persons, groups and companies to popularize their products.
2. Construction work:
During demolition of old sites and construction of new buildings huge machines which produce a lot of noise are being commissioned and it has become a common scene in every big city where construction work is in progress. Huge machines used in construction work produce a lot of noise. A lot of noise has been created during the construction of repair work of roads in cities. This noise is hazardous to a common man.
3. Road Traffic:
A great role for the increase of noise pollution has been carried out by various types of road vehicles especially by auto vehicle. Generally no regulation has been observed in blowing of horns and use of defective silencer pipes except in some specific zones. Road traffic- noise affects those persons in great extent who live adjacent to roads.
The penetration of vehicle noise into residential area is known to occur over considerable distances from the major road routes. Furthermore, it is known to be a function of the type of vehicle (diesel truck, passenger car etc.), the type of tires used and the road surface over which the vehicle is driven, the way in which the vehicle is driven, and the condition of the silencer or muffler.
The varying traffic conditions (motorway, urban city), the concentration of vehicles (heavy commercial, private etc.) and the speeds at which the traffic is allowed to flow all influence the noise patterns.
Measurement and analysis of such noise sources therefore inevitably present considerable problems, and numerous attempts have been made to quantify/model the noise exposure patterns in various environmental situations. Automobiles constitutes largest group of creators of noise. In cities 60-70% of noise may come from road traffic.
The steam engines used by Railways produce a lot of noise. Fast trains are being introduced on various routes of railways and they are also contributing to the noise pollution.
The impact of the noise pollution by trains has been reported to the maximum in those areas where railways track pass through residential areas. Noise from railway operations is by no means as serious a nuisance as noise from other transportation systems. However, concern has been expressed over the past few years about the effect of high-speed trains running through residential areas, particularly in view of the adverse reaction, against the high-speed trains in Japan.
The use of aircrafts of many types has been generating various types of noises. The higher the speed of an aircraft the greater the noise pollution the invention of supersonic aircrafts has added more noise for the plight of persons who live near aerodromes.
The takeoff and landing of an aircraft produces unbearable for a normal human being. The noise of supersonic jet planes may sometimes break windowpanes, crack plaster and shake buildings. By these effects of noise one can very easily and fully understand that what would be the effects of such noise on human body.
6. Radios and Microphones:
Radios and microphones can cause noise pollution if they are switched on with high volumes. Recent day interest in Western music and dance by youngsters with high volume causes noise pollution.
7. Agricultural Machines:
Tractors, thrashers, harvesters, tube wells, powered tillers etc., have all made agriculture highly mechanical but at the same time highly noisy. Noise level 90 dB to 98 dB due to running of farm machines has been recorded in the State Punjab.
8. Defence Equipment:
A lot of noise pollution is added to the atmosphere by artillery, tanks, launching of rockets, explosions exercising of military airplanes and shooting practices. Screams of jet engines and sonic booms have a deafening impact on ears and in extreme cases have been known to shatter the windowpanes and old dilapidated buildings.