| We describe the propagation of acoustic waves through randomly layered media over distances much larger than the typical wavelength of a pulse that is emitted from a point source. The layered medium is modeled by a smooth reference background modulated by fast random small-scale variations. Using asymptotic methods, we arrive to the O'Doherty-Anstey (ODA) formula which describes the coherent part of the pulse in a deterministic expression up to a small random time correction.;An application on time-reversal is presented, where a pulse is sent through the medium, recorded in a small window, time-reversed, and then sent back towards the source. The striking phenomenon of enhanced refocusing occurs, where the randomness in the medium actually improves the spatial refocusing around the initial source. |
