TEENAGERS often unfairly get a bad name. Not every group of youths on street corners is out to cause trouble.

Sometimes, they are just friends, meeting up for a chat and a laugh together outside because they have nowhere else to go.

Even so, a large group can be intimidating, often without realising it. And there are some gangs in York who, by their loutish behaviour and petty thuggery, deliberately make people's lives a misery.

Now a Tang Hall shop has hit on a novel way of dispersing them. The Co-op store, in Tang Hall Lane, has had an ultrasound device fitted.

It emits a piercing, high-pitched noise - one that can only be heard by teenagers and those in their early twenties, because their hearing is more acute.

Dot Molloy, the shop's deputy manager, said they had been plagued by gangs of children hanging around and making nuisances of themselves for "years and years".

But the device certainly seemed to be working, she said. "They cannot stand the noise."

We'd never support any technology that put the health of young people at risk.

We wouldn't want to see these devices springing up everywhere in York. And we certainly don't want perfectly innocent teenagers to be targeted.

But where antisocial gangs of youths are causing a real problem - discouraging people from going into shops, for example, or intimidating locals - there is a case for at least trying the devices, provided they are used sensibly and only when absolutely necessary.