Noise Pollution - Environmental Pollution
Noise is unwanted sound or excessively high levels of sound. Noise pollution is not only an annoyance, but at sufficiently high levels, it may cause loss of hearing. Noise pollution has grown because of increased use of technology. The main sources of noise are: road traffic, railways, industrial operations, construction work, aircrafts, military artillery and ammunition and household electrical appliances. Sound or noise can affect us because of its loudness and pitch or frequency.
Frequency is the number of cycles per second called Hertz (Hz). For example, a radio station uses certain frequencies for the broadcast. The human ear is sensitive to the sound of frequency in the range of 20 to 2000Hz. Loudness is measured in decibel scale (dB), a tenfold increase in sound intensity is represented as 10 dB increase on scale.