<P> Chronic exposure to noise may cause noise - induced hearing loss . Older males exposed to significant occupational noise demonstrate more significantly reduced hearing sensitivity than their non-exposed peers, though differences in hearing sensitivity decrease with time and the two groups are indistinguishable by age 79 . A comparison of Maaban tribesmen, who were insignificantly exposed to transportation or industrial noise, to a typical U.S. population showed that chronic exposure to moderately high levels of environmental noise contributes to hearing loss . </P> <P> High noise levels can result in cardiovascular effects and exposure to moderately high levels during a single eight - hour period causes a statistical rise in blood pressure of five to ten points and an increase in stress, and vasoconstriction leading to the increased blood pressure noted above, as well as to increased incidence of coronary artery disease . </P> <P> Less addressed is how humans adapt to noise subjectively . Indeed, tolerance for noise is frequently independent of decibel levels . However, Murray Schafer's soundscape research was groundbreaking in this regard . In his eponymous work, he makes compelling arguments about how humans relate to noise on a subjective level, and how such subjectivity is conditioned by culture . He also notes that sound is an expression of power, and as such, material culture (e.g., fast cars or Harley Davidson motorcycles with aftermarket pipes) tend to have louder engines not only for safety reasons, but for expressions of power by dominating the soundscape with a particular sound . Other key research in this area can be seen in Fong's comparative analysis of soundscape differences between Bangkok, Thailand and Los Angeles, California, US . Fong's research methodology was modeled after Schafer, and the research findings show how not only do soundscapes differ, but they also rather explicitly point to the level of urban development in the area; that is, cities in the periphery - in Immanuel Wallerstein - speak - will have different soundscapes than that of cities in the core . Fong's important findings tie not only soundscape appreciation to our subjective views of sound, but also demonstrates how different sounds of the soundscape are indicative of class differences in urban environments . </P> <P> Noise can have a detrimental effect on wild animals, increasing the risk of death by changing the delicate balance in predator or prey detection and avoidance, and interfering the use of the sounds in communication, especially in relation to reproduction and in navigation . Acoustic overexposure can lead to temporary or permanent loss of hearing . </P>

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