Physiological effects of noise pollution
1. Acute Effects:
Such effects by noise depend upon the pressure and frequency. As is known, a sound of 65 (dBA) is the noise level for conversation heard at a distance of one meter.
Sound of 110 (dBA) gives discomfort and 135 (dBA) is painful and 150 (dBA) might kill a person. A sound level in the range of 110-150 (dBA), affects respiratory system, causes loss of physical control and other physiological changes might occur.
Loud sounds can cause an increased secretion of various hormones of the pituitary gland, leading to increased blood sugar level, reducing immune system capability, effecting liver, heart, brain and kidney
2. Chronic effects:
The major effect is hearing loss. A person exposed to high noise levels goes deaf more quickly compared to the person exposed to relatively noise free environment. Such effects depend on pressure, frequency and period of exposure. The hearing loss starts in the frequency range of about 4000 Hz.
3. Mental Health:
Noise affects mental capability, thereby reducing mind concentration and at higher frequencies leads to mental disorientation. Work Efficiency
Noise causes chronic headache and irritability, thereby reducing work efficiency.
4. Industrial Accidents:
Noise interfering with sound system might mask the warning signals, thereby increasing the incidence of errors making accidents more likely.
The sound signal is distorted if the frequency of noise coincides with it. Thus, we have to raise the volume of our TV set or radio set to overcome the interferences of noise frequency, thereby creating further noise.
6. Personal Comfort :
To maintain a healthy body and a healthy mind, one needs a minimum specific period of proper sleep. Noise may contribute to distress and emotional disturbance.
This effect is more severe on old people and children. For old people it might cause neurotic problems and for children, affect their behavioral pattern. Effects on Birds
Migratory birds are now found to be the victims of noise pollution. The high noise pollution, along with high-rise buildings around a place can reduce the number of migratory birds. Such an effect is already observed in Alipore Zoo in Calcutta. Whereas, the number of migratory birds was 15,000 in 1982 it became 2,000 in 1990.