"Noise pollution is disturbing noise with a harmful impact on the activity of human or animal life. The source of outdoor noise worldwide is mainly caused by machines and transportation systems, motor vehicle engines and trains. Outdoor noise is summarized by the term environmental noise. Poor urban planning may give rise to noise pollution; side-by-side industrial and residential buildings can result in noise pollution in residential areas. Documented problems associated with urban environmental noise go back as far as Ancient Rome. Noise from roadways and other urban factors can be mitigated by urban planning and better design of roads. Outdoor noise can be caused by machines, construction activities and music performances, especially in some workplaces. Noise-induced hearing loss can be caused by outside noise, such as trains, or inside noise, such as music. High noise levels can contribute to cardiovascular effects in humans and an increased incidence of coronary artery disease. In animals, noise can increase the risk of death by altering predator or prey detection and avoidance, interfere with reproduction and navigation, and contribute to permanent hearing loss."