A series of lines superimposed on a map representing equal levels of noise exposure. They show areas in which noise levels exceed a given decibel (dB) threshold.
-        Noise contours in airports.
As a result of flight traffic, noise impact is either observed or calculated for every point around the airport. Due to a difference in distance from the noise source, these values may vary sharply from one point to another. Noise contours are isolines or lines of equal noise impact, using LEQ (equivalent continuous sound level) or equivalent measures. These lines connect points where equal noise impact is observed or calculated.