Ok, well I have been hit by vehicles on various bicycles five times. Always follow the laws, ride the lanes, lights, blah blah blah. On my liter bike with an after-market exhaust, people mostly get out of my way.... so I mounted an air horn on my bike handlebars, people now see me magically.

At least that's better than loud exhaust pipes. Loud bikes activate the fight-or-flight system in a way that klaxons do not.

Maybe that's because the loud bikes have frequencies and intonation modulation close to those of a menacing voice? (or growl)

At least in Japan, some bikers (bōsōzoku) do on purpose some kind of sounds similar to somebody arguing angrily (and snarkingly!).

But I don't want to accept neither as a solution air horns and vuvuzuelas competing for my attention and for the privilege of prematurely obliterating my cochlear hair cells.

There are other ways, let's do this. We are smarter than that, aren't we.

> Bicycles don't need it, do they?

The traffic fatalities of bicyclists in cities would like a word with you...

And yet if I permanently had a siren on my bicycle you’d think I’d be an asshole.

I believe the solution is not loud noises.

There are plenty of other options.

Most importantly, slowing down cars in residential or dense areas. The slower vehicle traffic is moving, the less likely that a collision will be fatal. (By a lot!)