There are shops in Tokyo (and other countries) that emit a high pitched noise to keep teenagers from loitering
I'm in Osaka right now and you'll find those around the temples at night. They kill my ears but I'm the only one in my group that can hear them.
I think they're meant to scare cats away, but they work well for teenagers and people like myself (26)
I also frequently have to ask people to repeat themselves and can't hear what they're saying well in noisy environments. I think I have superhuman hearing loss.