Costley, R. D.: Artillery location: Battlefield acoustics in the First World War, in: Although acoustics has played a role in warfare for hundreds, if not thousands, of years, the First World War came after the technological advances of the late 19th and early 20th centuries that enabled more quantifiable and less subjective observations. In 1914, after the outbreak of the war, Frenchman Charles Nordmann, a Professor of Astronomy at the Paris Observatory at Meudon, conceived and developed systems for locating artillery by measuring the differences in the times of arrival of the sound from the artillery to different observation positions. In one system, humans made “subjective” observations; alternatively, an “objective” system recorded these sounds with carbon microphones. In July 1915, Colonel Coote Hedley, head of the Geographical Section of the General Staff in London, learned of Nordmann’s work on a visit to France and recruited Second Lieutenant William Lawrence Bragg to evaluate it. Bragg led the allied effort to improve and deploy sound-ranging systems. In developing the system, they encountered problems in sensor design, array design, wind noise, and outdoor sound propagation. The technical achievements gained and obstacles encountered will be described, along with the impact they made to the war effort. Permission to publish was granted by Director, Geotechnical and Structures Laboratory. Resources AUTHOR LIBRARIAN ADVERTISER General Information ABOUT CONTACT HELP 145/3, March 1, 2019.