My neighbor's barking dog is becoming a nuisance?

Ever since I moved in about 5 months ago, my neighbor's two big dogs have been constantly barking, especially at night. Whenever I walk outside in my backyard, the dogs will look through the cracks of the fence and keep barking until I go back inside. At night, they bark randomly and sometimes keep me up. I've called the police once but the owner didn't put the dogs up. This is becoming a problem and I need some suggestions as to what I can do to put this to a stop.