Post #1203841

@SuperMoosie @moz I like how the possibilities in the research included mechanical (possibly wheel-powered) air sirens. I have used a hand-crank air siren; there's a lot of stop and start needed! But regular DTMF tones played loud over a Bluetooth speaker might be close enough - the number 6 includes 770hz and 1477hz. The higher tone is just a courtesy to make it sound more like a bicycle bell; it's not critical for ANC. 666 FTW anyone?