.Science?
What's the Buzz? Rowdy Teenagers Don't Want to Hear It - New York Times
"BARRY, Wales - Though he did not know it at the time, the idea came to Howard Stapleton when he was 12 and visiting a factory with his father, a manufacturing executive in London. Opening the door to a room where workers were using high-frequency welding equipment, he found he could not bear to go inside.

'The noise!' he complained.

'What noise?' the grownups asked.

Now 39, Mr. Stapleton has taken the lesson he learned that day - that children can hear sounds at higher frequencies than adults can - to fashion a novel device that he hopes will provide a solution to the eternal problem of obstreperous teenagers who hang around outside stores and cause trouble."