PLAY IT LOUD.
I was at the Shuttle Landing Facility for the landing of STS-135 Atlantis, the last Space Shuttle flight, ever.
An approaching Shuttle generates shock waves off the nose and vertical stabilizer. When the wave passes an observer on the ground, it’s perceived as two loud booms. (In fact, the wings also generate shock waves, but they're close enough to the vertical stabilizer that they’re indistinguishable.)
I barely managed to start recording video just before the twin sonic booms hit. The audio quality isn’t great, but if you play it loud, you can get an idea of how loud it was.
The camera is pointed at the approach end of the runway, where very bright xenon lights are pointed down the length of it.