Shock Wave Formation Simulator
kousen.github.io
kousen.github.io
If you want to see a supersonic boom, switch to moving target at just over mach 1, and turn the sound on. And you can see you can still get much of the effect from a non-supersonic flypast. So hearing a "boom" does not necessarily mean something is supersonic.
Still cool!
later I tried to google some of the phrases that I remembered, but couldn't find anything