Smarter Every Day is Destin Sandlin's engineering channel. In this 2018 episode he uses schlieren imaging, an optical technique that reveals changes in air density, to film the shockwaves around a supersonic bullet in ultra slow motion. The description links to Veritasium's own schlieren video and to background reading on Mach angles.
This is not cymatics in the plate-and-sand sense, and Sandlin does not call it that. It belongs here because it is the other route to visible sound: instead of making a surface respond to a wave, you make the wave itself visible in the air. Schlieren rigs are within reach of a determined hobbyist, needing a point light source, a parabolic mirror and a camera.
The firearms content will not be to everyone's taste. The optics are the reason to watch.