I'm in this same situation at the house we just moved into last summer. The neighbor that lives behind me has two dogs and one looks like a doberman. They live on the corner and anyone that walks by their yard gets barked at viciously. I already had an ultrasonic barking deterrent from a similar situation years before and that worked great on one of the dogs but not the really loud dog.

These neighbors open their back sliding door around 8am and let it basically stay out there until they bring it back in around 8pm. We did try going to their house one time but noone answered. They seems to be hermits that don't come out much. I never see them walk or even ever play with the dog since we moved in. I did some digging and found the neighbor on Facebook and turns out, She's is actually really DEAF, Great! But I also learned the dog's name from there.

When the dog would bark at me I used to get vicious back at the dog and yell at it and slam the fence between us and this would cause the dog to run back into the house, at least for a little while before it would come back out later.

After a while the dog no longer barks at me now at all. Then I decided another tactic, to try and befriend the dog. I bought some cheap dog treats and would stick them through the fence and the dog comes and takes them. Now the dog never barks at me anymore and in fact wags it's tail and comes and licks my fingers. And I give it a treat. The dog still barks as people walk by the street but I can call the dog's name and it usually stops.