1. A method of determining a cross-spectral correlation function for use in computing an acoustic response of a structure to a known acoustic field, the method being performed by computer-executable instructions stored on a computer readable storage media that, when executed on a processor, perform a method comprising: retrieving a finite element model of the structure having a plurality of elements with each element having a centroid; determining a plurality of composite centroids, each one of the composite centroids being based on at least one of the elements and having a spatial position; determining a cross-spectral correlation function of the structure based on the composite centroids; and determining the cross-spectral correlation function between at least one pair of the elements in the finite element model by performing one of the following: assigning the cross-spectral correlation function between the elements of the pair to be the cross-spectral correlation function of the structure for the composite centroids to which the pair of elements belongs if the composite centroids are distinct; assigning the cross-spectral correlation function between the elements of the pair to be an autocorrelation function of the composite centroid if the composite centroid is common to the elements of the pair; wherein the acoustic response of the structure to the known acoustic field may be predicted using the cross-spectral correlation function applied to the finite element model of the structure.