Please do yourself a favor, read my first post again. Specifically,
Usually only people who have actually been through this process know these things. So be careful, because a lot don't, but act like they do.
So for example when I say something like blocks twice the sound, that is because when you build it you will notice about half the sound getting through. If I wanted to sound all snotty and impressive I could spout dB specs all day and all night. This is the difference between trying to inform and trying to impress. Really wish the BSD types would catch on.