Just to let you guys know, I did search this forum for some info before posting. I'm planning a HT for our finished basement. The room has old paper/cardboard 12"-square ceiling tiles. Above that is about 6" of space and the bottom of the hardwood floor above. As it stands now, I have 2 main problems I need to address: (1) Any loud sound can be heard in upstairs bedrooms, even a lowly boom box! (2) Bass from the subs. I realize this is much more difficult to deal with due to traveling vibrations. For now, I'd like to deal with problem #1, dealing with loud volumes (100hz and higher) and ref peaks of 105db. I went to Home Depot last night and found the R11 stuff. It's the only one (I think) that was labeled for its "sound" properties. Common sense dictates that since this R11 is only 3.5" thick, the thicker stuff should be better for absorbing/blocking the sound? But the thicker stuff doesn't mention sound. * Why should I use the R11 at only 3.5"? Is it denser than the others? * The R(#>11) stuff is thicker. How is it for sound? * Maybe 2 layers of R11 or one layer of the R Thicker stuff? Squishing it in there shouldn't be too hard. Thanks. Rich B.