Retrieving the scattering strength using noise correlation in a reverberant medium

Abstract

We explore how ambient-noise interferometry can serve to track variations in the distribution of scatterers within a medium. Experiments are conducted in the presence and absence of a single scatterer that can occupy different positions within the propagation medium. We calculate the similarity between the Green's functions obtained in these cases (i.e., with versus without the scatterer) as a measure of the temporal variations in the Green's function, which shows exponential decay with respect to time. We also develop a formula that relates this decay to the scattering strength of the scatterer. The formulae are experimentally validated using experiments in a strongly reverberating duralumin plate. This proposed method for finding the scattering strength of the scatterer is based on information carried by the coda of the multiple echo arrivals. We confirm the reliability of this approach through a conventional method for the measurement of the scattering strength that is based on direct arrivals.

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• Toward Forecasting Volcanic Eruptions using Seismic Noise
• Fluctuations of correlations and Green's function reconstruction: role of scattering
• Green's function retrieval and fluctuations of cross density of states in multiple scattering media
• Coda reconstruction from cross-correlation of a diffuse field on thin elastic plates