Noise Pollution

Noise pollution can be defined as the loud disturbing sound dumped into the ambient atmosphere without regards to the adverse effects it may have. Sound travels in pressure waves and affects our eardrums. The intensity of a sound wave is the average rate per unit area at which energy is transferred by the wave on to the surface. The sound level is the logarithm of ratio of the ambient intensity to the reference intensity (usually considered 10-12 W m^-2). The unit of sound level is decibel (dB). When the ambient sound intensity is equal to the reference intensity the sound or noise level is 0 dB.

Noise level can change from 0 to more than 120 dB, at which point physical discomfort starts. In view of the logarithmic nature of scale, 10, 20 and 100 decibels represent 10 times, 100 times and 1010 times the threshold intensity respectively. Man-made noise originates from industrial machines, transport vehicles, sound amplifiers, cracker blasting, industrial and mining the detonation, etc. Jet aircraft landing and takeoff create a lot of noise pollution to the inhabitants near the busy airports. Noise has many ill effects on human psychological functions. Noise seriously affects heartbeat, peripheral circulation, and breathing pattern. Persistent noisy environment can cause annoyance, irritability, headache, and sleeplessness and may seriously affect productive performance of humans. The Central Pollution Control board has recommended zone wise ambient noise levels.

Control of Noise Pollution

Soundproof insulating jackets and filters are used to reduce noise from machines. Industrial workers and runway traffic control personnel may use earmuffs to protect themselves from unwanted noise exposure. Acoustic zoning to prevent noise propagation may also be helpful. A â€˜silent zoneâ€™ around 100 meters of hospitals or schools can give comfort to ailing patients or help students to concentrate in studies. Forests and dense hedge of plants can effectively act as noise barrier. Sound must be considered as a potentially harmful pollutant around us and should be treated with no less importance than the other pollutants of our environment. Efforts must be made to increase awareness among people about the perils of noise in our surroundings.