Comparison between calculation models for the evaluation of aircraft noise impact considering the influence of hill orography on the acoustical propagation

The research consists of the analysis of the discrepancy between calculation models used by computer softwares. Different scenarios had been analyzed taking account of the orography for differents aims; in the first case it has been considered for the only reduction of the distance between source and reciver, in the second one for all the physical phenomena involved in the acoustical propagation. The project is divided in three distinct parts. a) Simulation of aircraft noise impact in different scenarios: typical day and calibration day for the Commercial Aviation; overfly of a single aircraft for the General Aviation. All the simulations are based on ground tracks and elevations obtained from really flight parameters and procedures. b) Comparison between noise level perceived at ground in a detailed grid of points in order to evaluate the effects of orografy. The differences between the two analyzed models had been leaded back to real causes: screen effect, reflection and multiple reflection, ground absorption. c) Comparison between the results obtained from the simulation and the ones obtained from an on-site measurement session during the calibration day.