Explainer: Locating a gun with sound waves
In WWI, scientists used sound waves to find big guns
Scientists used microphones to locate and destroy killing machines like this, the remains of a German gun.
Great War Primary Document Archive: Photos of the Great War - www.gwpda.org/photos
Suppose that the boom of a gun is recorded by three microphones: Let’s call them A, B and C. Assume that the three microphones are spaced 386 meters (1,266 feet) apart. That is the distance sound travels through air in one second. The boom reaches microphone A first. One second later it reaches microphone B. One second after that it reaches C. Draw a circle with a radius equal to 386 meters centered on B and a circle with radius twice that distance centered on C. Now draw a circle that goes through the position of microphone A and that also touches the two other circles. The center of this circle is the position of the gun that fired.
