Abstract: Methods and apparatus for identifying the source location of acoustic emissions generated within or on an acoustically conductive medium segregated into a plurality of quadrilateral monitoring zones. A plurality of acoustic receivers are communicably coupled to the surface of the medium respectively at the zone corner locations. Each receiver is responsive to the reception of an acoustic emission to provide a corresponding electrical output. The electrical response of the respective receivers are coupled to corresponding counters in a manner to enable the counters to sequence through their respective counting states. The receiver outputs are monitored to identify the first zone exhibiting an acoustic reception at all four corners. Once such a zone has been identified, all counters are inhibited from sequencing and are locked into the last counting state cycled.