Noise Pollution

Noise is a sound that is unwanted, disagreeable, and disturbing.The world and its cities steadily grow noisier. Public health doctors and specialist in hearing disorders use term "noise pollution" to describe the menace of prolonged unpleasant sound.

For centuries, noise has been a nuisance. Scientists and physicians have gathered evidence showing the effect of excessive. Besides a temporary or permanent loss in hearing acuity(sharpness), constant exposure to loud noise can cause nervousness and fatigue. Doctors think it may also responsible for some illness. But apart from its effect on health and hearing, noise marks sound that people want to hear, hinders concentration, and interferes with sleep.

Vibrations are the source of all sounds. Sound waves travel outward in all directions from the vibrating object, as, for example a loudspeaker or the turbulant gas of a jet engine exhaust. Generally, the sounds we hear come to us as waves a second. The loudness or softness of the sound that we hear depends on the amplitude with which the vibrations reach our ears. Generally, the greater the intensity of the sound wave, the louder that sound seem to us.

In hearing loss caused by prolonged exposure to excessive noise, the high - frequency cells wear out first. A person may not realize for some time that he is no longer hearing high-pitched sound well. If excess noise continues, the middle frequency cells wear out next, and finally the low-frequency cells.