Array Processing for Noisy Data: Application for Open and Closed Wind Tunnels

Array processing represents an extremely important area in aeroacoustics: in particular, in the development of methods to extract the useful characteristics of acoustic sources, such as their locations and absolute levels, starting from the received sound field. Generally, the methods are based on a deconvolution operation to remove the undesirable effects of smearing produced by array response. This process should be carried out after the additive noise has been suitably attenuated and, ideally, the deconvolution operator should amplify the noise as little as possible. We show that, when a noise reference is known beforehand, and under certain assumptions, that it is possible to both remove the smearing effect produced by array response and to reduce the noise contamination of the results using a method called the spectral estimation method with additive noise. This method has been applied to computer and experimental simulations involving acoustic sources radiating in a noisy environment. The levels of the sources were found with good accuracy, and the background noise was highly reduced, confirming the validity of the approach and the good performance of the proposed method.