The SAE A-21 Committee on Aircraft Noise undertook in 1979 the development of a uniform and consistent method for the prediction of lateral attenuation. The project was divided into two phases: (1) A short-term phase in which correlations of flight data were made using frequency-weighted and time-integrated measures of the noise, such as Effective Perceived Noise Level (EPNL) and Sound Exposure Level (SEL), see Appendix A; and (2) A long-term phase in which the effects of various sound-propagation phenomena would include ground reflection effects, refraction effects, and airplane shielding effects, as well as other ground and engine/airplane installation effects. This Aerospace Information Report is directed to the short-term phase in order to produce an interim prediction method as soon as possible.
