Noise consists of all unwanted sound - sound that is loud, unpleasant or unexpected.
It has been increasing in urban areas to the point where it has become a matter of public concern. This noise is caused by traffic, industrial and recreational activities. The effects of noise can vary from one individual to another. Initially, action to reduce noise was not considered an environmental priority - unlike action to reduce air pollution, for example. The effects of noise are unspectacular, and the decline in quality of life was accepted by the general public as being an inevitable consequence of technological progress and urbanisation.