The generation of unreasonable noise within the environment is regarded as a form of pollution because it lowers the quality of life. There have been several specific ways in which excessive noise can affect people adversely.
Noise has been found to interfere with our activities at three levels; (a) audio logical level in referring with the satisfactory performance of the hearing mechanism; (b) biological level interfering with the biological functioning of the body; and (c) behavioural level affecting the sociological behaviour of the subjects. Because of this the noise affects categorically, performance, physiology and psychology.
Noxious has been known to cause of nervous disorder, headache, high blood pressure and short memory. The various effects of noise may be as follows. Various psychological effect of noise pollution is summarized below:
(a) Depression and fatigue, which considerably reduces the efficiency of a person.
(b) Insomnia as a result of lack of undisturbed and refreshing sleep.
(c) Straining of senses and annoyance as a result of slow but persistent noise from motorcycles, alarm clocks, call bells, telephone rings etc.
(d) Affecting of psychomotor performance of a person by a sudden loud noise (sound)
(e) It is a cause of frustration and is associated with difficulty in concentration, disturbance of rest, physical and mental fatigue. Low frequency noise of 50 to 60 dB affects the higher centre of brain and causes an alternation in the normal sleep pattern and prevents sound sleep.
(f) Noise, which is an annoyance also causes irritation dis-satisfaction, dis-interest and affects work “performance. Noise has been reported both to improve and to decrease work efficiency, depending on its intensity, duration and frequency distribution etc.
Various physiological as well as pathologic effects of noise pollution are as under:
(a) Noise pollution affects human health, comfort and efficiency. It cause contraction of blood vessels, makes, the skin pale, leads to excessive secretion of adrenalin hormone into blood stream with is responsible for high blood pressure.
(b) It causes muscles to contract leading to nervous breakdown, tension and even insanity.
(c) Noise effects are anxiety, stress reaction and fright. These adverse reactions are coupled with a change in hormone content of blood, which in turn produces increased rate of heart beat, constriction of blood vessels, digestive sperms and dilation of pupil of eye.
(d) 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 eardrum. Prolonged exposure to noise of certain frequency pattern will lead to chronic damage to the hair cells in the inner ear.
(e) Auditory fatigue appears in the 90 dB associated with whistling and buzzing in ears. Temporary deafness occurs at 4000-6000 Hz, and this effect is known as Temporary Threshold Shift (TTS), Permanent loss of hearing occurs at 100 dB due to continuous noise exposure. Under such conditions, the auditory threshold shift is called Permanent Threshold Shift (PTS). Besides chronic hearing loss, there may be instantaneous damage or acoustic trauma, which may be caused by very high intensity impulsive noise resulting from an explosion or sudden excessive noise of more than 150 dB.
(f) Physiological effects of noise pollution include neurosis, hypertension, increase in sweating, hepatic diseases, giddiness, peptic ulcers, undesirable change in gastro intestinal activities behavioural and emotional stress.
(g) Noise mainly interferes with man’s communication. It is easily visualized that a conversation can be carried on in whisper in a still place, while one his to shout to make sense in a noisy factory.
(h) Blood gets thickened by excessive noise. Changes in breathing amplitude have also been reported due to impulsive noise.
(i) Noise causes cosinophilia, hyperglycarmia, hypokalaemia and hypoglycarmia by a change in blood and other body fluids.
(j) Noise causes chronic headache and irritability; work, which needs a high degree of skill, is considerably affected. The overall working efficiency goes down when noise level goes up.
(k) Loud and sudden noise such as sonic boom produces a startle effect, which may damage the brain. Sonic booms can also cause physical damage to property i.e. windows may break due to it. Sudden noise can be much more harmful than a continuous noise.