More pollution is continuously increasing due to development of industry, heavy machinery, technology and modern modes of transportation. Sometimes children also cause loud noise. Noise is measured in units of decibel (dB), the word Bell is in the memory of Alexander Graham Bell. One decibel is the smallest amplitude which can be heard by the human ear. Animals can distinguish some sounds better than human beings. The approximate sound and noise level values of some operational activities are given below: Whispering 20 decibels Quiet library 40 decibels Normal conversation 60 decibels Vehicular noise 70-80 decibels Printing press 80 decibels Motor car horn 100-120 decibels Train passing a station 110 decibels Jet aeroplanes 140 decibels The recommended maximum noise level is 85 decibels.
A noise at 100-120 dB is uncomfortable and at 130-140 dB is painful to ears. Exposure to noise above 160 decibels results in rupture of tympanic membrane and permanent deafness. This may happen due of exposure to sudden noise of an explosive nature. In India activities like marriages, ceremonies, festivals, religious and political activities are not held without the use of loud-speakers and Address systems which cause noise pollution. The use of loudspeakers at the religious places daily in the early morning and evening hours is also a great source of noise pollution. The activities like Jagrans, Ramlilas and marriage ceremonies which are carried out at night time cause noise pollution. The worst affected from these loudspeakers are the students preparing for their examinations, sick and old persons.
Effects of Noise:
(i) Loud noise may cause direct injury to the auditory organs resulting in deafness. (ii) Prolonged exposure to any noise of 80 dB or more is likely to be harmful and may produce fatigue, headache, tinnitus (whistling, ringing or buzzing sound in the ears) vertigo and deafness. (iii) It leads of annoyance and irritability. (iv) It interferes with speech. (v) It leads to inability to concentrate. (vi) Sleep is disturbed.
(vii) Habit of loud speaking develops. (viii) It leads to certain accidents in industries. (ix) Certain physiological changes such as increase in blood pressure, heart rate, sweat, nausea, giddiness and visual disturbances may occur.
