Simple Flying - Matthew Austin Ryan
Noise is generally measured in decibels, but there are many ways those measurements are used and interpreted to determine levels of noise pollution.
Especially for major airports that are immediately surrounded by local communities, noise pollution is often a major concern.
...noise pollution is unique from other forms of emissions in that it depends less on the physical characteristics of sound as on human reactions to it. As such, there is no unified set of international or national limits for noise pollution; rather, the concern revolves around its localized impact on people's health and quality of life, which can make its measurement and regulation a less-than-consistent activity.