I’ve already written about merchants using classical music to discourage loitering. Young people don’t like the music, so they don’t stick around.
Here’s a new twist: high-frequency noise that children and teenagers can hear but adults can’t:
The results were almost instantaneous. It was as if someone had used anti-teenager spray around the entrance, the way you might spray your sofas to keep pets off. Where disaffected youths used to congregate, now there is no one.
At first, members of the usual crowd tried to gather as normal, repeatedly going inside the store with their fingers in their ears and “begging me to turn it off,” Gough said. But he held firm and neatly avoided possible aggressive confrontations: “I told them it was to keep birds away because of the bird flu epidemic.”
At least he didn’t claim it was an anti-terrorism security measure.