A METHOD FOR THE EFFICIENT CONSTRUCTION OF ACOUSTIC PRESSURE CROSS-SPECTRAL MATRICES

A method is presented for constructing, with the minimum number of physical measurements, the full cross-spectral matrix of acoustic pressures associated with a number of measurement positions. It is necessary to evaluate the elements of the matrix in question when using inverse methods for the reconstruction of acoustic source strength spectra. The method presented uses the concept of “reference microphones”. The relation between the rank of the cross-spectral matrix of acoustic pressures and the number of uncorrelated acoustic sources is discussed and used to determine the required number of reference microphones. A method is proposed for selecting this number in the inverse problem in which information regarding acoustic sources is unknown. The results of computer simulations are presented which explore the main features of the technique under various conditions. Experimental results are also presented which validate the technique.