Concerning the sound flanking from walls to untreated ceiling. I know you're supposed to leave a gap between each flat surface so that it is not in direct contact with the next surface, such as wall to ceiling, or wall to wall, or wall to floor. Then this gap gets filled in with some sound damping material, like green glue, but not green glue. (Just can't remember what it's called.) It seems that this should eliminate most of the flanking.

https://docs.google.com/spreadsheet/ccc?...amp;usp=sharing