Godin, O., 2006: Recovering the acoustic Greens function from ambient noise cross-correlation in an inhomogeneous moving medium. Phys. Rev. Lett., accepted.
Abstract
We study long-range correlation of diffuse acoustic noise fields in an arbitrary inhomogeneous, moving fluid. The flow reversal theorem is used to show that the cross-correlation function of ambient noise provides an estimate of a combination of the Green's functions corresponding to sound propagation in opposite directions between the two receivers. Measurements of the noise cross-correlation allow one to quantify flow-induced acoustic non-reciprocity and evaluate both spatially averaged flow velocity and sound speed between the two points.