What is "sound ranging"

n. locating a source of sound (as an enemy gun) by measurements of the time the sound arrives at microphones in known positions

In land warfare, sound ranging is a method of determining the coordinates of a hostile artillery battery using data derived from the sound of its guns (or mortar or rockets) firing. The same methods can also be used to direct artillery fire at a position with known coordinates.

Sound ranging is sometimes confused with sound location (acoustic location), which is location of the source of other sounds that may originate in the air, on the ground or on or below the water's surface. This entry is primarily concerned with artillery use. Sound ranging was one of three methods of locating hostile artillery that rapidly developed in World War I. The others were air reconnaissance (visual and photographic) and flash spotting.

Sound ranging using aural and stop-watch methods had emerged before World War I. Stop-watch methods involved spotting a gun firing, measuring the bearing to it and the length of time it took the sound to arrive. Aural methods typically involved a man listening to a pair of microphones a few kilometres apart and measuring the time between the sound arriving at the microphones. This method appears to have been used by the Germans throughout that war, but was quickly discarded as ineffective by the western allies, who developed scientific methods of sound ranging whose descendants are still used.

The basis of scientific sound ranging is to use pairs of microphones to produce a bearing to the source of the sound. The intersection of these bearings gives the location of the battery. The bearings are derived from the differences in the time of arrival at the microphones.