Atmospheric Propagation Model Validation with the NRC Convair 580 Aircraft

In today's environment of urbanization, the ability to model the impact that aircraft noise will have on a given community is of increasing interest. It is for these applications that NRC undertook the characterization and validation of an acoustic atmospheric propagation model for the assessment of aircraft audibility. The NRC Flight Research Laboratory's twin-engine Convair 580 aircraft was utilized as an acoustic source and the Smiths Falls Montague aerodrome was selected as the testing environment location. Acoustic data was recorded using five independently time-synchronized acoustic measurement stations located throughout the aerodrome. Low altitude aircraft fly-by acoustic measurements were first considered to characterize the acoustic signature of the aircraft, while high-altitude fly-by acoustic measurements were conducted to validate the performance of the atmospheric propagation model. The atmospheric models accurately and consistently produced acoustic spectra in agreement with the high-altitude fly-by measurements although it was observed that there was a slight degradation in the model performance for the estimation of tones over large distances; the degradation is likely related to atmospheric turbulence. Optimal low background noise conditions exhibited a modelled characteristic tonal amplitude within 1dB of the measured tone.