[dn3500]

Children too. My own hearing extended to about 23 kHz until I was in my early 20s, and I don't think I was exceptional. There was a jewelry store in my town that I couldn't go in to because the "ultrasonic" motion detector was so painfully loud. But I doubt these devices would be a problem for children or pets because the pulse is so short.

[pavel_lishin]

My hearing is still keen enough that when I'm biking around, I avoid certain streets because those houses have anti-rodent ultrasonic systems that hurt my ears.

[simpleintheory]

Are you sure it wasn’t one of these? https://en.wikipedia.org/wiki/The_Mosquito

[dn3500]

Yes. This was more than 50 years ago. The store owner let me examine the device. It was wired into his alarm system. It even had the frequency listed on the label.

[madaxe_again]

I mean, TV. Kids were definitely a market for it, throughout its history, but until the flat panel era nobody cared that the flyback transformer in most CRTs made a deafening whine in the 20khz range. I could walk into a house and hear a soundless TV three rooms away, and I know I wasn’t alone in that.

[Animats]

Not quite that high. Around 15KHz. (15,734 Hz for NTSC, 15,625 Hz for PAL.)

[invalidSyntax]

Yeah I could too(not know though...). Trying to sleep, and knowing your parents are watching TV in the living room few doors away isn't the best experience.

[drfloyd51]

That’s what that was? I had no idea. I just knew I could hear muted TVs whine. I asked my parents about it. They couldn’t hear it. So I wasn’t sure if it was real.

I feel so relieved.

[Ajoha]

Sorry, humans cannot hear up to 23kHz. Our hearing ends at 20kHz. Point. After a decade on earth your loss is already at 18kHz or less. (Loss means not: you hear nothing but you do not hear as good as when you where born).

[Neywiny]

Incorrect https://en.wikipedia.org/wiki/Hearing_range#Humans

If it's 28 in perfectly ideal conditions, 23 is well within range