  This study contributes to the evaluation of the robustness and accuracy of
Green's function reconstruction from cross-correlation of strongly dispersed
reverberated signals, with disentangling of the respective roles of ballistic
and reverberated ('coda') contributions. We conduct a suite of experiments on a
highly reverberating thin duralumin plate, where an approximately diffuse
flexural wavefield is generated by taking advantage of the plate reverberation
and wave dispersion. A large number of impulsive sources that cover the whole
surface of the plate are used to validate ambient-noise theory through
comparison of the causal and anticausal (i.e., positive- and negative-time)
terms of the cross-correlation to one another, and to the directly measured
Green's function. To quantify the contribution of the ballistic and coda
signals, the cross-correlation integral is defined over different time windows
of variable length, and the accuracy of the reconstructed Green's function is
studied as a function of the initial and end times of the integral. We show
that even cross-correlations measured over limited time windows converge to a
significant part of the Green's function. Convergence is achieved over a wide
time window, which includes not only direct flexural-wave arrivals, but also
the multiply reverberated coda. We propose a model, based on normal-mode
analysis that relates the similarity between the cross-correlation and the
Green's function to the statistical properties of the plate. We also determine
quantitatively how incoherent noise degrades the estimation of the Green's
function.
