The Sharper Image store makes a device that puts out an ultrasonic sound that is anoying to dogs and stops the barking. A friend got me one for my neighbors early morning barker.
LOL...one of my employees had the barking dog and his neighbor put one of those things up...the dog would bark and this devise would beep.......the dog would keep barking at the devise instead of stopping...like the dog was having a bark off contest with the ultrasonic bird on the fence.
In other words it didn't work, it made it worse.