Ernie, here is what I was thinking of

[Link: m.petsafe.net]

Turns out their site is a dot net (I had forgotten that). pet safe is the parent company of invisible fence brand. this piece works well. although your situation is tough for any solution because of the distance and the walls. If memory serves, (I have one of these somewhere around the house) there is a test option that manually triggers the ultra sonic tone. So even if the unit can't detect the dog's bark, you could still make it work. Also, I imagine that this piece could make a good starting point for modifying into a much stronger tone generator to cover the range you need