In principle you can. The biggest problem are reflections and multipath (which are also problems for locating earthquakes). Also, classifying whether a noise

In principle you can. The biggest problem are reflections and multipath (which are also problems for locating earthquakes). Also, classifying whether a noise came from a gun, when heard from far away in an urban environment with lots of other noises around, is hard. Simplest method is trilateration. By knowing the travel time from multiple places, you can figure out the source point.