I have a home theater now that is open on one side. I'm thinking about closing the open side off so I can soundproof the theater. However I want to make sure I don't create some nasty room modes. I remember that I should avoid multiples of each other in the dimensions (ie length 2x width etc.) I remember there were some ratios that are good and some that are bad, but I can't remember what they are. I would appreciate some help. Thank you.