Interferometric reconstruction of plate waves from cross correlation of diffuse field on a thin aluminum plate

This study contributes to evaluating the robustness and accuracy of Greenu0027s function (GF) reconstruction by cross-correlation of noise, disentangling the respective roles of ballistic and reverberated (“coda”) signals. We conduct a suite of experiments on a highly reverberating thin aluminum plate, where we generate an approximately diffuse flexural wavefield. We validate ambient-noise theory by comparing cross correlation to the directly measured Green’s function. We develop analytically a theoretical model, predicting the dependence of the symmetry of the cross correlations on the number of sources and signal-to-noise ratio. We validate this model against experimental results. We next study the effects of cross-correlating our data over time windows of variable length, possibly very short, and taken at different points in the coda of recordings. We find that, even so, a relatively dense/uniform source distribution could result in a good estimate of the GF; we demonstrate that this window does not have t...