[noefingway]

Exactly this. When I was 17 I worked at a JC Penny store as a stock boy. Every time I approached certain entrances (like the main one that opened into the shopping mall) and other areas of the store my ears were assaulted with a high pitch squeal. Never figured out what it was, nobody else seemed to hear it. I've always had tinnitus, and the frequency always seemed to be the same. In fact, I'm listening to it now.

[Moru]

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.

[cafard]

What year was this? I never encountered such a noise in my stock boy days, but I bet they were a lot earlier than yours (early to mid 1970s).