I could see "there's a message being transferred, and it's just outside of our ability to sense it" being catnip to the kid in all of us. Like invisible ink han

I could see "there's a message being transferred, and it's just outside of our ability to sense it" being catnip to the kid in all of us. Like invisible ink handwritten notes for adults. I looked up specs, my mic doesn't go beyond 20KHz. Do clubs like this still exist? I get the sense that I wasn't alive when they were most popular.