Hi Denny,
It is great to have you back. I have missed your thinking outside the box approach and lively discussion.
Sound and heat insulation (in my x-spurt opinion) have different components.
The first component is direct transmission of sound and heat. All the holes and gaps must be filled. This includes even the tiny ones. This is a cheap and easy way to get a lot of benefit.
Sound insulation is improved by the installation of mass. For instance two layers of drywall in a home or a layer of limp mass vinyl
http://www.auralex.com/sound_isolation_sheetblok/sound_isolation_sheetblok.asp will filter out lower frequency sound. The flexible flashing from a building supply store is an attempt at this. My question though is what if I or someone else want to remove this material in the future. It is an aggressively sticky product.
A third component of sound and heat insulation is dead air space. This is accomplished by the addition of fiberglass or welding blankets or bubble wrap.
