There are a couple of things you can try. The one that works the best for me is having a spray bottle of water, with a little bit of viniger in it, just enough to leave a viniger smell, and I spray it at their heads and say no bark. They don't like the smell of viniger at all. Another thing is to have a plastic soda bottle or a soda can, and put some pennies or small stones in them. When the dogs bark, shake the can/bottle to make a racket and say no bark. When they do stop barking remember to give them plenty of praise so they catch on to what you want.