Have seen a few stores and public places installing speakers pushing out a high pitch tone to irritate youth so they won't hang out where they aren't wanted. Was it some trial run on this tech maybe? :-)

It's designed to be just outside of hearing for adults so only kids and youth can hear it. Did a simple test with our daughter and she can hear quite a bit higher frequencies than we can so apparently it's a thing. Except I can hear higher frequencies than my wife so not very useful I guess.