Hybrid approach for deconvoluting tonal noise of moving sources

Kurzfassung

For the assessment of noise reduction measures on aircraft and aircraft engines, flyover measurements are necessary to provide a realistic estimation of their effectiveness. The use of microphone arrays improves the ability to localize the sources and quantify the noise levels of different components of the aircraft. The department of Engine Acoustics at the German Aerospace Center uses a hybrid approach, where in the first step, a delay-and-sum beamforming (CBF) is executed in the time-domain followed by a deconvolution, similar to DAMAS, in the frequency domain. While the algorithm used at DLR relies on the assumption of broadband sources, where the loss of energy from one frequency band to neighboring bands can be assumed to equal to the gain from these bands, this may not hold true of tonal sources and requires a new approach. While good results can be achieved with the current approach for practical applications, this paper investigates the feasibility of interconnecting neighboring frequency bands in the deconvolution step and the resulting benefit in the localization of tonal sources from fly-over measurements