We all know the sound of an aircraft flying over, and that when we look up at the sky there is no aircraft to be seen, at least not where we thought it would be. That can be quite annoying, but it sure isn’t the only thing that can be annoying about aircraft noise. For example, aircraft noise has quite a strong directivity and especially with landings you hardly hear the aircraft approach. It’s suddenly there, giving an impulse-like feeling. Very unpleasant.
Within the SONORUS project I’m dealing mainly with aircraft noise and, to be more specific, with the auralization of aircraft noise. The idea is to develop a tool that can synthesize the sound of fly-overs. Thus tool can then in a later phase be used to perform sleep disturbance and annoyance studies.
You might ask now why to synthesize the sound if we could also simply record it? The answer is simple, synthesis gives a controllable environment, allowing you to adjust any parameter as you like. And this gives many nice opportunities. For example, with synthesis you could investigate new flight trajectories, and this gives together with already existing noise prediction tools the possibility for further optimization of the trajectories and the development of urban environments.
Development of the tool progresses well and currently efforts are focused on the development of an emission model specifically for aircraft auralization. What is distinct about this model is that it not only predicts average noise levels in say 1/3-octave bands, but will also predict the power and frequency of the tones.