I am always so surprised and appalled that these things are still legal. Can you imagine the reaction if they were designed to only hurt pretty much any other demographic other than young people?
It’s fundamentally an attack on public space and should be illegal. I’m sitting in a small public parkette right now within earshot of an establishment that has one of these things running 24/7. I don’t even know which one as I can’t locate the precise source of the sound. It emits a high pitched whining noise for about 5 seconds, at which point the frequency rapidly increases until it ends in a zap, followed by about 2 seconds of silence. This differential makes it impossible to ignore. It even permeates headphones. I like eating lunch here, as it’s close to my office and a nice space, but I often leave irrationally angry after being unable to relax in the midst of this omnipresent noise.
Sadly there doesn’t seem to be anything I can do about it.
They are easy to locate. The sound can't pass through your hand and doesn't diffract much, so move your hand around at arms length till you can't hear it anymore in one ear, and that's the direction it's in.
Normally they're metal boxes with a grille on the front mounted above head height (because otherwise some teen would put gum in the grille to stop the sound getting out)
Sadly there doesn’t seem to be anything I can do about it.