1. A method of locating an object producing an acoustic wave, the acoustic wave being detected by a plurality of passive acoustic detectors formed in an array to produce at least three signals, the method comprising: (a) determining a wavelet correlatable with each of the at least three signals, said wavelet being derived from an acoustic wave of a known form; (b) determining time difference of arrival (TDOA) measurements between the at least three signals using correlation intensity with said wavelet; (c) performing acoustic reciprocity at a pre-determined time interval from each of the plurality of detectors based on said TDOA measurements resulting in a hemisphere centered around each of the plurality of detectors; (d) examining hemispheres produced from step (c) to determine an intersection point of at least three hemispheres; and (e) repeating (c) and (d) with a further time interval to increase the size of said hemispheres if said intersection point is not determined; wherein said intersection point represents a location of the object.