[grujicd]

Earshot NGO analyzed recorded sounds and found 4 of these videos "consistent with Vortex Ring Gun or Vortex Cannon":

https://x.com/earshot_ngo/status/1901661518153781534

Note that many videos didn't record the sound if the phone was further away from that center line.

This is the recording which perhaps captured sound the best:

https://x.com/stonexman/status/1901034916961309148

[user_7832]

Thank you. Before I saw your reply, I saw this discussion and links on r/acoustics which in retrospect seems to be the best likely answer. It being a cannon (and not a speaker based device) would mean it’s closer to a controlled explosion than a speaker playing (really loud) music.

There’s still the questions of “how is it so small” (apparently) but at least some aspects are answered now.