For anyone interested nrc-ir-766 doesn't address the issue we are talking about. 1st.. They state "insulation at the top, middle, or bottom showed no difference" The thing is you can have insulation at the top, without it touching or the bottom without it touching. They weren't testing what we are talking about. Also 766 is "testing joist/ceiling assemblies with a tapper" This is for impact noise/footsteps. On the 2nd or 3rd page of the summary they state "using insulation/absorption material show no difference in assemblies that did not use resilient channels" Now if you go to the link below, the first example is where putting insulation in wall cavities shows between 4 and 5 stc gain.
http://www.stcratings.com/assemblies.html..We need something different than 766. I do not have any data saying it will "add dampening" Nor have I seen any data thus far proving "it virtually does nothing" I would love to see some one with some real data on this subject. So I apologize for passing on information that is considered common knowledge in some circles, but that I can't prove. I'll be more careful in the future.
