I'm trying to find the article I've seen on sound deadening and insulation. I'll post up the link if I find it. I think the take away was that mass affixed to broad unsupported areas is best for cost-effective sound deadening while thicker padding like jute padding or cheap insulation rolls you can get at Lowe's works well for insulation (from sound and heat/cold). It's sort of a two-tiered approach.