Popular imagery of the atom bomb is oddly sterile.

For all we know of the horrors of nuclear weapons, the visual that’s most often evoked is ethereal, if ominous: a silent, billowing cloud, aloft in black and white.

The reasons for this are understandable. Nuclear weapons have been tested far more often than they’ve been used against people. And the only two times they were used in warfare—in Hiroshima, then Nagasaki, 72 years ago—photographers captured many scenes of devastation, yet video recording was scant.

Survivors of the bombings have shared what they saw and heard before the terror. John Hersey’s famous report, published in 1946 by The New Yorker, describes a “noiseless flash.” Blinding light and intense pressure, yes, but sound? “Almost no one in Hiroshima recalls hearing any noise of the bomb,” Hersey wrote at the time. There was one person,  a fisherman in his sampan on the Inland Sea at the time of the bombing, who “saw the flash and heard a tremendous explosion,” Hersey said. The fisherman was some 20 miles outside of Hiroshima, but “the thunder was greater than when the B-29s hit Iwakuni, only five miles away.”

There is at least some testing footage from the era that features sound. It is jarring to hear. The boom is more like a shotgun than a thunderclap, and it’s followed by a sustained roar. Here’s one example, from a March 1953 test at Yucca Flat, the nuclear test site in the Nevada desert.

The National Archives description of the footage is matter-of-fact—which is the purpose of archival descriptions, but which seems strangely detached, considering: There’s the mountain ridge in early morning. An atom bomb is exploded. Burning. Pan of the mushroom against darkened sky. The cloud dissipates as the sky lightens. A yucca plant and Joshua trees in foreground. Hiller-Copters buzz in. And, finally, General John R. Hodge standing at a microphone, blinking into the morning sun.

“This test, I think, went very well,” he said. “I was quite interested in how the troops reacted. I didn’t find any soldier there who was afraid.”

“They took it in stride,” he added “as American soldiers take all things.”