General Characteristics of sound in relation to Noise pollution Sound is made up of longitudinal waves that travel through air and cause certain materials to vibrate and create sound. The common characteristics of sound are intensity, frequency, amplitude and velocity. Sound cannot travel in outer space because it is a vacuum. (Ron Kurtus, 2009) According to Kurtus atoms and molecules that float in outer space are too far apart to actually cause any vibration or sound. A loud explosion in outer space would hardly be heard because of the vacuum. Unlike electromagnetic waves that easily travel through space through electrical and magnetic fields, sound waves are caused due to vibration of matter. (Ron Kurtus, 2009) Sound intensity in relation to Noise Pollution The intensity of sound varies from human to human due to varying hearing sensitivity and therefore cannot be generalized. Sounds which could be normal for some could be harsh for others. Sound frequencies ranging between 1000 Hz and 5000 Hz seem most sensitive to the human ear. However, a normal human ear with the right hearing ability has the lowest threshold of approximately 4000 Hz for comfortable hearing. When sound intensity goes beyond this threshold it tends to impact on the ear causing damage. Such intense sounds include loud explosions, blasts, crashes and noise from heavy machinery etc. Prolonged exposure to such intensity of sounds is liable to lead to permanent damage. Sound intensity is described as the average rate of sound energy flow across a perpendicular surface in the line of propagation. Sound intensity is measured by special units, namely, bel and decibel which are logarithmic. If there is an increase of 1 bel, the intensity of the sound increases ten fold. An increase of 1 dB increases the intensity by approximately 25% and the change in audibility can hardly be detected. The threshold for human hearing is 0 dB sound intensity. The intensity of sound decreases as distance is increased. (www.physicsclassroom.com) Frequency of Noise Pollution The frequency of noise pollution is as important as its intensity and therefore prolonged or frequent exposure to noise is another contributing factor that lowers an individual’s quality of life. The intensity of sound that exceeds above 90dB or even lesser but recurs repeatedly over long periods of time either at work or ones own home, is sure to cause damage to the ear. Damage leads to a deterioration in audibility and could progress into permanent loss of hearing if not checked in time. Therefore, it is advisable to use hearing protectors especially when exposed to noisy environments on a regular basis. Noise pollution in relation to the quality of life Noise pollution is a major contributing factor to discomfort and stress in human beings. In fact it is a crucial threat to an individual’s quality of life especially for those who work in factories and industries with heavy machinery that creates a lot of sound. In this contemporary age, the latest technology brought about by industrialization poses a major threat to human beings as well as causing ecological damage. Noise pollution is no more only an urban problem because even in rural areas noise from heavy machinery from industries or factories and farm implements have added to the problem.