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NOISE POLLUTION , SOURCES AND EFFECTS OF NOISE POLLUTION :

Noise pollution  is defined as, the unwanted, unpleasant or disagreeable sound that causes discomfort for all living beings.                    


Unit Of  Noise ( Decibel ) : 

The sound intensity is measured in decibel (dB), which is one tenth of the longest unit Bel. One dB is equal to the faintest sound, a human ear can hear. 

Noise level :

Normal conversation sound ranges from 35 dB to 60 dB . Impairment of  hearing takes place due to exposure to noise of 80 dB or more. Noise above 140 dB becomes painful. 

Types and Sources (causes) Of  Noise :

It has been found that environmental noise is doubling every 10 years. generally noise is describes as, 

1. Industrial noise - Heavy industrial machines etc.,

2. Transport Noise  - Unwanted horns and sounds

3. Neighbor hood noise - Speakers etc.,

                

Effects of Noise Pollution : 

i) Industrial pollution affects human health, comfort and efficiency. It causes contraction of blood vessels, makes the skin pale, leads to excessive secretion of adrenaline hormone into blood stream which is responsible for high blood pressure. Blaring sounds have known to cause mental distress, heart attacks, neurological problems, birth effects and abortion. 




ii) It causes muscles to contract leading to nervous breakdown, tension etc., 

iii) These adverse reactions are coupled with a change in hormone content of blood, which in turn increase the rate of heart beat, contraction of blood vessel, and dilation of pupil of eye.

iv) It affects health efficiency and behavior. It may cause damage to heart, brain, kidneys, liver and may also produce emotional disturbances. 

v) The most immediate and acute effect of noise is the impairment of hearing which diminishes by the damage of some part of auditory system. When exposed to very loud and sudden noise acute damage occurs to the ear drum. Prolonged exposure to the noise of certain frequency pattern will lead to chronic damage to the hair cells in the inner ear. 

vi) In addition to serious loss of hearing due to excessive noise, impulsive noise also causes psychological and pathological disorders.

vii) Ultrasonic sound can affect the digestive, respiratory, cardio vascular systems and semicircular canals of  the internal ear. The rate of  heart beat may also be affected. It may decrease (or) increase depending on the type of noise. 

viii) Brain is also affected by loud and sudden noise as that of jet and aero plane noise etc., People are subjected to psychiatric illness.

ix) Recently it has been reported that blood is also thickened by excessive noises. 

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