Sources of noise pollution
The main source of noise pollution is transportation systems especially motor vehicle. The other sources are aircraft noise and rail noise. Besides transportation noise, other sources are office equipment, factory machinery, appliances, power tools, lighting and audio entertainment systems. Construction equipment also produces noise pollution.
Effects of noise pollution
Due to heavy industrialization, exposure of high level of noise gives rise to stress factor in modern life. It may leads to many hazards.The effect of noise on health depends on both, loudness and frequency. Any source producing sound levels of more than 80 to 90 db (decibel) for more than eight hours is harmful to human ear.
Frequency of sound is denoted by Hertz (Hz). Human ear can hear frequencies between 20 to 20,000 Hz. Effect of noise on human health depends on i) quality ii) duration iii) sensitivity of the individual the noise pollution produces the following three main effects:
i) Psychological effect
Noise leads to emotional disturbances, however, are difficult to measure. Irritating noise at work place reduces concentration efficiency and working capacity. ii) Masking effect
Masking noise prevents the ear from registering other important sounds and signals. These effects change the balance in predator /prey detection, by disturbing and interfering the sounds of communications especially during reproduction time period and loss of hearing. iii) Physiological effect
a) Auditory
• Auditory fatigue (when level of noise ranges from 85-90 db)
• Deafness (repeated exposure to noise level > 90 db)
b) Non auditory
• Annoyance (listens dislike the noise content)
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