ABSTRACT
Acoustic modeling around airports is intended to satisfy the needs of many users. Its nature ranges between sophisticated noise spectrum modeling and pragmatic noise environment assessment in terms of cumulative noise exposure or, by means of dose-response relationships, predictions of the size of the population annoyed by the noise in the area of concern.1−3 It must be noted that the form and structure of the noise indices, whichmust be assessed and investigated around the airport or under the particular flight path, have a dominant influence on the method used for their assessment. Methods for modeling noise radiation, propagation and attenuation include both analytical and semi-empirical techniques. The current tendency is toward less empirical and more analytical techniques. It should be noted that the International Civil Aviation Organization (ICAO) is carrying out analyses of existing models and methods for assessing aircraft noise events and is making proposals for their use.4,5
Two approaches to analysis of aircraft noise phenomena have been defined and implemented in computer programs. The first approach is based on the third-octave band spectra noise analysis of any type of aircraft in anymode of flight or during maintenance activities in the vicinity of or inside the airport. The corresponding prediction of the aircraft noise under the flight path or around the aircraft on the ground (run-ups, taxiing, queuing along the runway before the takeoff) is based on the sound wavefront spreading along the shortest distance between the aircraft and the point of noise control. This approach is implemented in well-known computer programs, like ANOPP (USA) and Flula (Switzerland). The BELTRA program (Ukraine) combines two large modules: BELTAS – for noise assessment at points of interest around the source and hence derivation of the directivity pattern of a noise event, and TRANOI – which indicates the need for noise control under the flight paths.
