Well, where the story mentioned that the loitering consisted of mouthing off to passerbys and the like, I would suggest the store owner call the cops.
I've seen telecommercials for similar devices that use soundwaves to drive off cockroaches, rodents, and other pests from homes. It's just kinda telling to me for people to endorse a device that equates young people with cockroaches.
And let's not kid ourselves, if these things are for real and did go on the market, they wont only be used against trash-talking punks; plenty of yuppy retail storeowners who want to attract the right clientel will be hooking these babies up to clear their stores of any teenagers. Of course, it's discrimination, prejudice in the extreme, but teens can't vote, so who cares, right?
I really don't think these things would make it to the market though; if the younger the harsher, and these things are supposed to be annoying enough to drive off late teens, what would they do to passing 12-year-olds, or toddlers?
But I digress, as usual. I suppose I should put it this way: if they came out with a device that emits sound waves that would only be annoying to women, or blacks, or gays, or hispanics, I'd expect that such devices would be, to put it lightly, frowned upon. Please tell me why one that does this to teens is any different, or any less immoral.