Are car horns (in the US) really in the key of F?

I’ve read this over and over, but I don’t really believe it. Are car horns in the US really in the key of F?

My car horn is a G

I’ve heard that, too, but it’s never really made a lot of sense to me. Something that only produces a single note can’t be in the key of ANYTHING. It’s not like your car horn is going to play a song (those third-party contraptions that everyone had hooked up to their cars for two weeks in 1983 that played things like the Dukes of Hazzard fanfare notwithstanding).

Considering how most are sounded, I can’t imagine it was intended as anything other that an F.

I have heard in the past that most car horns produce an F or F#.

According to this site, and who knows if it’s true…

Aha! That’s where the misunderstanding was (on my part, naturally)! Every time I’ve heard this “factoid” it was that the horns were in the key of F, not that they produced the note “F”.

60’s and 70’s era cars had 2 horns that sounded simultaneously. We used to make fun of those little tiny foreign cars that went meep meep with only one horn. Of course, now every car goes meep meep with just one horn, but really old cars used to make a chord. Sort of.

My kit car has an aaoogah horn. I don’t know what key you can say “aaooogah” is in.

In the 60s and 70s all General Motors (Chevy, Olds, Pontiac, Cadillac, and GMC) horns were made at Delco Remy here in Anderson. The lower priced cars had two notes, the fancier ones had three, and the Cadillacs had a chord they called the Klaxon Quartet. An old friend was a horn engineer, and he told me it was a diminished seventh, something you might hear in Barbershop Quartet music. Now you know nearly everything I know about car horns.

On the old DR horns, there was a little adjustment screw that was used to tune the horn on the assembly line. It won’t tweak the note very much, but if you fiddled with it, you could make your horns a little more irritating to a listener with a good pitch sense.

If I remember correctly, the two horns were piched a half-tone apart. The dissonance would gather more attention from the honkee.

Chord schmord.

Some fellow railfans on a railway message board I visit actually bought a surplus “five chime” horn from a diesel-electric locomotive, and mounted it on the roof of their pickup truck. They have an air cylinder in the tray of the truck to drive the horn. When they stop for fuel, they just top up the air with the tyre pump.

That thing kicks all manner of arse.