Good grief Dan. This one would be easy to answer if your house was located in Iraq, and this was happening back in 91', lol! I have heard what seems to be joists & studs moving/shifting, but I've never heard what could be titled a "bang". How old is the house? I know that in some of the older buildings, the water pipes will make loud noises when warm water is pushed into them, but those noises really aren't bangs. Good luck and sorry I couldn't be more help.