It really is not overboard to call on a fight you can hear? At very least it's disturbing the peace.... and also let's the people know that someone cares enough to call. At most you can have help on the way if something drastic takes place because that can happen quickly? The police don't mind either way though
I used to live in a complex with a house arrested husband who beat the shit out of his wife next door and I'd call the cops every time while I hid in a closet so I couldn't hear what was happening. She did finally say something though because he was arrested and she mov d out