Noise Pollution

In our lives, we can see that noises are created by human activities and everything around. The main cause of noise world wide is transportation system including road traffic, air traffic and rail traffic. Road accounts for approximately 70% of total noise emissions by transportation. It must be noted that different road transportation modes have different scales of noise emission. For this factor, noise comes from the engine and the friction of wheels over the road surface. Also, air has been the cause of considerable concern which is about 20%. When taking off, it can provide noise about 120 decibels that is the high levels of noise. This noise comes from the jet engine, the aerodynamic friction and ground craft operations. In addition, the remaining percentage of total noise emissions by transportation is covered by rail traffic coming from the engine (mostly diesels), the friction of wheels over the rails and whistle blowing. In fact, when trains are moving at high speed, areoacoustic noise becomes more important than other sources. Beside that, Industrial machinery is another cause of noise pollution resulted in residential communities. For example, machines in the factory are running during working hours for manufacture. Thus, the longer you work the more you hear from the machineries. Also, noise pollution is caused by construction of buildings and infrastructure. Noise usually comes from trucks and equipments which are used to establish new building. Moreover, both domestic and neighborhood are the other significant sources of noise including barking dog, car alarms, garbage recycling, lawn-mowers and household noise. Among these, noise from barking dogs is particular concern because it is unpredictable and often happens repeatedly.