As the round passes them, they can first hear the crack as the bullet breaks the sound barrier, then the thump of the round being fired. With a firearm like an AR-15, says Beale, who spend more than 24 years in the British Army, soldiers learn to recognize the sounds of high velocity rounds through training that places them in a range where shots are fired behind a bank. And “getting used to gunfire on a gun range, if it’s indoors, is going to make you familiar with the sound of gunfire in that environment, but it’s going to sound different if it’s outdoors,” Smyth says.
Additionally, different guns will sound different from one another. To them, “It’s distinct from from a car backfiring or fireworks or pyrotechnics.” But for civilians, seeking training in professionally simulated situations would be necessary to pick up the difference in timbre and volume. Frank Smyth, executive director of Global Journalist Security, which does the same for journalists and NGO professionals, says those who have lots of experience around live, high-powered rifle fire will be able to recognize its sound relatively quickly, if not immediately.
