I’d never thought of this!
The link above offers some high pitched sounds for you to listen and judge how high a pitch you can hear.
The story is that if you are under 20 you may still be able to hear tones over 17kHz but older folks can’t. I could hear the 12kHz but nothing higher.
So some folks got the idea to use these tones as teen repellent! Just by blasting them in areas teens hangout and adults don’t want them the teens tend to go away.
Kids, have now begun to use these tones as cell phone text message ring tones. That way when they get a text message the teachers can’t hear them receive their messages.