a method and system for multiple microphone photoacoustic leak detection and localization . the leak detection technique uses photoacoustic sounds produced by the interaction of a carbon dioxide laser turned to 10 . 6 microns and a photoactive tracer gas , sulfur hexafluoride , emitted by calibrated leak sources . as the leaked gas is heated by the laser , it expands and launches a photoacoustic sound pulse . the sound pulses generated by the scanning process are recorded across a broad bandwidth by multiple ultra - sensitive microphones . after the photoacoustic pulses arc recorded , the magnitude is compared with background noise measurement at several frequencies for a determination if a leak is present . if the presence of a leak is found , then the location of the leak is determined . the recorded sound is processed by using matched field processing as the signal processing technique . the photoacoustic sounds recorded at the microphones are reversed in time through computer simulation that causes the sounds to converge to the apparent point of origin . no synchronization between the acoustic signal processor and the laser scanner is required .