Verification of comparison between measurement and prediction results of lateral attenuation derived from equations used in aircraft noise prediction

摘要

It is indispensable to take account of lateral attenuation when modelling airport noise. Our 1751M equation is a modified reformulation of AIR 1751 that we proposed 15 years ago. It is useful under various weather conditions expressed by vector wind and temperature gradient. Furthermore, when ground-to-ground sound propagation is expressed, the evaluation value is a little less than AIR 5662 which was proposed in 2006 by SAE. Also, it showed that air-to-ground lateral attenuation rapidly decreased when elevation angles of sound arrival direction became higher than about 12 degrees. Since then, however, much time has passed and a lot of new types of aircraft have been introduced, so rechecking of the validity of 1751M for current aircraft models is needed. Thus, in recent years, we have examined whether existing equations such as SAE/AIR 5662 and our 1751M can correctly evaluate lateral attenuation for flyover noise of late model aircraft, using results of long-term noise monitoring and repeated short-term noise measurements obtained. This paper describes the verification of comparison between measurement results and prediction results which by using multiple lateral attenuation equations, (mainly with elevation angles of 10 - 30 degrees), shows a remarkable difference between 1751M and 5662.