Reliability of aircraft noise evaluation by measurement for comparison with prediction

摘要

This paper discusses the reliability of measured airport noise evaluation compared with prediction. In Japan, airport noise mitigation measures are performed based on yearly-average airport noise predictions. It is necessary to realize a high reliability in predictions, which are determined by comparing them with noise measurements in order to confirm their validity. However, various factors including microphone height, SN ratio and SEL calculation procedure and incomplete observations affect the reliability of measured noise evaluation. When evaluating yearly-average aircraft noise using short-term measurements, the reliability changes dependent on the measurement period in addition to the afore mentioned factors. Thus, it is necessary to estimate the long-term average using short-term noise measurements and result of continuous noise monitoring or average aircraft operation number. The sound of airport ground activities such as APU or taxiing can be heard in the surroundings of the airport, but the sound propagation significantly changes dependent on meteorological conditions. In other words, airport ground noise becomes louder and audible only in cases of favorable conditions for sound propagation. But, evaluation of yearly-average sound exposure due to aircraft noise requires average-day sound exposure of the year. So, it is necessary to consider what conditions we should suppose for noise measurement.