Not a joke. Apparently there is some high pitched frequency that as people get older they can’t hear anymore. It’s used in some places to keep teens away. Conversely, some teens use it as ringtones so they can keep their phones on in class. Oh those wily teens.
The cut off is supposedly 25. But I can still hear it and I’m 25+.
Prepare to feel old. Or young if you can hear it. Good luck.
