There was a news story a few years ago about higher-end retailers in the US playing high frequency tones in order to keep kids from loitering and whether that was fully legal or not. Damn kids. Get off my lawn!
Even at my advanced age of 31, I can hear 16,000 Hz, which is maybe a bit surprising considering how many shows I’ve been to and the fact that I like to stand really close to the speakers. But I always wear earplugs at gigs and I used to feel really geeky about it, but then I would see cool people also wearing earplugs and most musicians too, so now I’m like, “Ear protection. Fuck yeah!” Also, the guys on All Songs Considered always wear plugs and they’re professionals.
I also wonder if using ear buds over headphones makes any difference? Maybe the volume can be lower on ear buds because it blocks more ambient noise than headphones do. I don’t know. I wear ear buds too.