I dont mind the idea of these devices being installed on shops to deterr large groups I live in a peacful neighbourhood and one of the houses near me has got one of these devices installed and now i dont get a wink of sleep when my windows are open. it drives me insane. I cant go into my room and have a window open without hearing that noise. I think these devices should be for shop use only otherwise if large numbers of houses get them some people wont even feel comfortable walking down the street.