Good sound insulation does not have to be continuous to make a difference, but it is best if it is. Often just small patches on any flat panel, especially metal or fiberglass can be quite effective as it stops the panel from vibrating. Automotive car stereo stuff can be helpful. But I doubt a foam with one layer of foil does much more than keep heat in. (Keeps engine at operating temperature, and keeps it out of the cabin) The best foam for noise will have a sandwich of lead or other heavy foil in between two layers of foam. It will be quite a bit heavier than one would think by looking at it. I believe that is the foam that Shawn is referring to.