Campaigners want to ban ultra-sonic device used against young people . ` The devices are known as'sound cannons' and have been banned in the UK since 2003. About 3,500 of the devices are used in England to disperse young people . Human rights groups say they create divide between young and old .
Campaigners want to ban ultra-sonic device used against young people . `` The Mosquito '' emits sharp sounds that can only be heard by under 20s . About 3,500 of the devices are used in England to disperse young people . Human rights groups say they create divide between young and old .