Of course this requires compensating for the loss in awareness through hearing by looking more diligently before crossing a bike lane, but unfortunately, some people never learn this, or only through a few close calls.
"Annoyingly" ringing a bell and converting a potential accident into a close call seems pretty close to optimal to me.
> People should not hear loud music when driving - max is normal speaking voice level.
which feels like a more than acceptable constraint to me.
Oh, completely agreed on that one. In a car, you are also by far better protected than any cyclists you might encounter, so you shouldn't make it harder to hear their signaling. (I still wouldn't rely on any car having heard my bell if I don't get any other confirmation that the driver has noticed me, e.g. sufficiently slowing down as they are approaching the intersection where I have right of way.)
But GGP also said
> People should not wear headphones (noise-cancelling or not) when going through traffic as pedestrians. Take them off when crossing!
and that's what I think goes too far. Why should I remove my headphones if I look both ways before crossing a bike lane or road?
The ideal rule would of course be that only those pedestrians remove their headphones that are otherwise inattentive... Although I have my doubts that they'd remember.
Other things like loudness levels inside cars cannot be monitored without going in full totalitarian mode.