Some guy, I think it was in Great Britain, discovered that if he broadcast a particular pitch just outside of his store, it discouraged the teens who liked to loiter there. They could hear it, but older people could not. Older patrons would shop, teens would skedaddle. Before long his son started giving away or selling the tone to teens as a ringtone. They could hear it, but teachers, say, could not. So they could get text messages in class and the teach would not be the wiser.
It's unusual for people over the age of 25 to hear this whine.
I am well over that age. I have not been kind to my ears. Yet, for reasons I do not quite understand, I heard it.
Created by Teenage Mutant Ninja Annoying Sound
Wait'll your dog or cat is near your computer before playing it, if you want to have a little extra fun.
I could only hear it after playing it 3 times. On the second I thought I might have, but had to confirm it on the 3rd.
50, and 25 years of construction noise and I can hear it.
Surpisingly, I did hear it.
I spent some years in submarines under the ships of other countries while wearing headphones. And I was not a sonar guy. Consequently, there may be some hearing issues. But mostly I get by.