Not a huge difference but I thought it was 300 meters. That would be 328 yards or almost 1000 feet.
I would like to know what is in between the OP home and the neighbor? Are there several other homes, trees, etc...or is it an open field? I would have a difficult time believing that someone could hear and see all of that from so far away at such a wee hour if there are lots of obstructions, but if there is an open field on a quiet night, I could see better that sound can travel that far. It is still pretty far though. 3 1/4 football fields!!! That's pretty far!!!