Annual noise assessment in the vicinity of airports with different flights’ intensity

Abstract

The noise metric recognized as universal to describe aircraft flight noise events and community noise pollution as a whole has not been yielded yet. Among a set of factors that impacts aircraft noise perception is a number of flights – number of aircraft noise events. This article deals with the number of flights’ influence on applicability of the usually used environmental noise metrics: equivalent Leq and maximum Lmax sound level for the long-term interval of their observation. The correlation between Leq and Lmax levels is considered against duration of observation interval. As a result the definition of representative duration is obtained. Noise measurements provided within representative time interval allow to assess the annually averaged value of equivalent sound level adequately. The adequacy or representativeness of measurements results is based on accuracy criterion taking into account the ‘noisiest’ events only for long-term Leq evaluation procedure under consideration. The long term noise descriptors are considered as the parameters of averaged ‘virtual’ flight noise event, for which the both Leq,avg and Lmax,avg are interrelated through averaged sound exposure energy for all events in observation. The results show that for airports with low intensity of flights (around 5 events per hour during the day) the long term equivalent sound level is heavily changing in relation with the long term maximum sound level, but for high intensity flight traffic this interrelation is quite stable. In the vicinity of airports with low flight intensity the maximum sound level as a noise impact metric is more sensitive than the equivalent level. Inside the areas, where the value of mandatory descriptors Lden (Ldn) is in conformity with established limits for environmental noise, proposed statistical post-processing analysis provides to recognize some additional reasons of community annoyances. The proposed in article assessment scheme was applied for data sets collected at the points of noise control closely to airports with low (about 30 flight noise events per day – Vilnius airport) and high (200–250 flight noise events per day – Madrid-Barajas airport) flight intensity.