Acoustic waves exhibit force that pushes objects along the direction of sound propagation. Precise motions require well-focused beams. The technique of time-reversal acoustics (TRA) overcomes beam distortions introduced by propagation along irregular paths to focus sound without knowledge of the medium properties. TRA requires a small receiver to be placed at a point of desired focus. The invention disclosed refines TRA by introducing data matching schemes to extend the points of focus beyond the location points of the receivers. With as few as two receivers, a large region can be manipulated with well-focused acoustic beams and with no receiver at a desired point of focus. Applications are described in drug delivery in medicine environmental fluid contaminant control and in oil exploration, for retrieving oil stuck in underground pockets.
