At high levels, noise is a serious pollutant that can cause much damage to health. It is a nuisance that produces much psychological stress and discomfort.
Increase in road, rail and air traffic is a chief source of noise pollution, which is particularly acute in big cities in India. Misuse of loudspeakers, hooting of motor horns, firing of crackers, playing of music records and radios at high pitch are other important sources. Yet another important source is religious discourses broadcast on loudspeakers, sometimes through a whole night.
Some people are quite indifferent to the effect of noise on others, showing little or no consideration to the neighbours whether the occasion is a wedding, a political rally, a religious occasion, or a procession of agitating strikers. India is one of those few countries which permit such unsocial activities to go on without much concern for the welfare of the general public.
Image Source: fmslondon.co.uk
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This state of affairs contrasts with those in countries such as USA, UK, Switzerland, and France where loudspeakers are banned and traffic noise is highly regulated. In Japan, no flights are permitted to land or take off during night hours.
Exposure to high levels of noise can produce adverse auditory effects besides general stress.
Noise levels are expressed on a logarithmic scale of decibels. The most commonly used unit is the A-weighted decibel, dB (A). The baseline noise levels in the community vary around 40 dB (A). International standards prescribe a maximum of 50 dB (A) for day and 40 dB (A) for night time in any residential area.
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Delhi, Mumbai and Kolkata are the noisiest cities in the world (Mukherji et al., 1980). In these the minimum recorded noise levels are over 60 dB (A) with the maximum averaging around 90 dB (A).