It's actually two "bangs" for a plane. Tum-dum. Source: grew up about 100km away from a military air base in Russia at which at least a couple planes went super

It's actually two "bangs" for a plane. Tum-dum. Source: grew up about 100km away from a military air base in Russia at which at least a couple planes went supersonic almost every day for years. You can hear several sonic booms in this video, although they're from low-flying planes: https://www.youtube.com/watch?v=jmhU7SEo4gg https://www.youtube.com/watch?v=jmhU7SEo4gg. The higher the plane, the more distinct and "bassy" the "booms". Here's another example, a bit higher, a bit more distinct: https://www.youtube.com/watch?v=M_KbZON5sW0 https://www.youtube.com/watch?v=M_KbZON5sW0