Noise pollution: Any unwanted sound is called noise. High intensity sounds emitted by big machines, industries, factories, automobiles, aeroplanes, etc. are unwanted sound. Use of loudspeakers in public meetings, etc. a high volume of radio, TV and transistors increases the noise level. The pollution caused by it, is called noise pollution. The intensity of sound is measured in decibels. The intensity of sound in normal conversation is 30-50 decibels. 

Effects of sound pollution on human beings: 

1. Audiological effects: Sounds of more than 90 dB intensity, causes fatigue in the ears and roaring in ears, continues. Persons living in the noise of 100 dB become hard of hearing or deaf. If the intensity of sound is very high and the source of loud sound is near the ears, the eardrum gets punctured and deafness is produced. 

2. Physiological effects: Harsh and unwanted sounds affect the physiological working of the human body. Sound pollution harms the vision of the eyes, and working of the heart, liver, respiratory system and brain. Sound pollution causes headache, nausea, irritation in skin, high blood pressure, vertigo and loss of memory. 

3. Psychological effects: Harsh sound causes anger, irritability and mental tension. It gives birth to quarrels and disputes among the people. 4. Other effects: Sound pollution interferes in lectures, speech and normal talk with other persons. The working efficiency of persons goes down. Sound pollution disturbs sound sleep and peaceful study.