Explainer: Locating a gun with sound waves | Science News for Students

Explainer: Locating a gun with sound waves

In WWI, scientists used sound waves to find big guns
Nov 10, 2015 — 6:45 am EST
german gun

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.

Power Words

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radius  A straight line from the center to the circumference of a circle or sphere.

range  The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which variation in values is possible. Also, the distance within which something can be reached or perceived.

Further Reading

R. Cowen. "Sounding out the enemy." Science News for Students, November 10, 2015. 

B. Brookshire. “Making cents of sounds.” Eureka!Lab. May 14, 2015.

A. Bridges. “Explainer: What are lidar, radar and sonar?Science News for Students. May 1, 2015.

S. Ornes. “Drones put spying eyes in the sky.” Science News for Students. November 6, 2014.

S. Ornes. “A new way to eavesdrop.” Science News for Students. June 20, 2013.

E. Sohn. “Explainer: What is acoustics?Science News for Students. December 14, 2011.