I have a neighbor who is inconsiderate when it comes to his big dog running around and this big guy seems to come to my yard to do his duty and then ripping up my grass after doing it. I have talked to them several times but it has not done any good. I have heard of whistles that the human cannot hear but the dogs can an don't like the sound of it. Apparently some you blow and some work with a battery. I see them for sale on the internet but don't know if they really work. Anyone have any experience with these whistles as far as running dogs off?