The air horn is a simple device, essentially some canned-air with a plastic horn on top. When pressed, the air rushes out through an orifice of a size tuned to make a loud noise. The noise an air horn makes isn't a specific note, rather just something right in the middle of the human hearing range where our ears are most sensitive. This doesn't have to be the case.
It's perfectly feasible to make a tone outside the normal human hearing range. You could go low, to make an infra sound, deeper than a fog horn, but this would require a LOT of air and a massive horn. This isn't practical. Making a high frequency is much easier, you need smaller components, and possibly higher pressure which is fine. So what tones are we aiming for... I suggest two separate air horns with different tones.
The first is at around 18kHz. This is above the hearing range of normal adult humans, but, crucially, within the hearing range of teenagers and younger children. It is, essentially a cheap, disposable use-anywhere mosquito <link>. This may be used by a responsible adult in a variety of scenarios where children might need to be distressed without inconveniencing everyone else.
The second model is even higher pitched. say, 35kHz designed to scare off the majority of animals, racoon rooting through your garden... give it a blast of the animal-specific air horn.-- bs0u0155, Feb 15 2021 Mosquito https://www.today.c...ched-sounds-t157801 [bs0u0155, Feb 15 2021] nice neon glow https://www.amazon....id=pla-765915929031 [bs0u0155, Feb 18 2021] Well, but quite a lot louder, and potentially mounted on a drone or other vehicle.-- bs0u0155, Feb 15 2021 If you COULD make one with a suitably deep, infra sound, you would have a rhino horn.-- AusCan531, Feb 15 2021 [kdf] huh. Well, that is very similar. I did a brief search and didn't pull that up. I'm surprised it was granted, it's quite broad. They didn't however, include teenager repellent as a major use case. Teenagers are clearly a larger menace than the combined animal kingdom...-- bs0u0155, Feb 15 2021 If you have one at 18kHz, you could make another at 19kHz or so. Then, if you need an audible noise, you blast them both at once.-- neutrinos_shadow, Feb 15 2021 //if you need an audible noise//
How unpleasant. How about a nice relaxing neon bulb to indicate the presence of a teenager repellent din? Or perhaps a streamer attached to the horn that would flap around in the expelled gas?-- bs0u0155, Feb 17 2021 More like <link>-- bs0u0155, Feb 18 2021 random, halfbakery