Speakers and ceiling..

As in another post I have a problem with bass response(not enough).I tried moving the speakers around to about every spot in the room with always the same result.My question is,is containing the sound in the room important for low frequencies ?My ceiling is made from wood frames with speaker cloth over them so it looks like a drop ceiling .Above the drop the floor joist and insulation would be visable so a lot of the sound leaks out.any help would be great.Thanks