Post #1203864

2026-04-08 10:41 UTC

@dec23k interesting. From the paper I understand the 750Hz tone is around 3dB less attenuated, but only in quiet areas with already not much noise, like parks. In noisy areas, any tone that is distinct from the noise is more easily heard. But everything is attenuated and the warning distance is considerably lower already. I wonder if these ANC headphone makers are obliged to support 'emergency' vehicle tone detection and not blank it out? Does anyone know? Or there is the air horn solution🤪

Replies (2)

@dec23k@mastodon.ie 2026-04-08 10:58

@Slash909uk Regular DTMF tones (played loud) might be close enough - the number 6 includes 770hz and 1477hz. The higher tone is a courtesy to make it sound more like a bicycle bell, so it's not critical for getting past ANC. 666 FTW? Anyone?

Open ##1203865
@dzwiedziu@mastodon.social 2026-04-09 06:33

@Slash909uk > I wonder if these ANC headphone makers are obliged to support 'emergency' vehicle tone detection and not blank it out? I would assume so, because of the potential legal liability. Yet 750Hz meets this only partially, as it's the lower range of the lower band of the UK's and few other European countries two-tone pattern¹. So that would assume there are more frequencies to take into account and wanted to check in with RTINGS tests, but they » @dec23k

Open ##1203866