Post #1203889
2026-04-09 06:36 UTC
@dec23k
750Hz seems weird, as there is no one emergency signal frequency, yet better than my idea of blasting directional infrasounds, to make pedestrians viscerally afraid of crossing cyclists' paths ^_^
Replies (1)
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@dec23k@mastodon.ie 2026-04-09 10:55
@dzwiedziu That 750Hz could be an artifact of the DSP in the headphone design, or even something as simple as the casing around the microphone causing a notch filter (not as dramatic as what they show in the video). I would expect it to be different across different manufacturers. If 770Hz is close enough, then playing the DTMF for 666 loud over a Bluetooth speaker should also work!