They leave the dogs in the back yard all day and they just bark. I finally had enough of it and when I looked over the wall the bigger dog ran up to me and started barking even louder. Sicne you cannot see through the wall it isn't possible to tell from the other side I had the garden hose. I blasted it square in the face with a full force jet and it shut up, at least for now.
It may take a couple of times for them to realize that the jet spray can hit anywhere in their yard and there is no place at the moment they can hide from it. At the moment the initial shock hasn't worn off, the dog probably wasn't ready for anyone to fight back.