Everything would be so easy if only that 1/16” thick product made of some unidentifiable material could achieve IIC ratings in the low 70′s regardless of the assembly. We could tell customers to install this wonder material, that essentially adds no height to their floor, and they will achieve ratings that previously only several inches of rubber underlayment or a ceiling suspended by wire over 24 inches could achieve. Or if that thin foam strip can be applied to the studs and joists for significant gains in airborne or impact isolation. It appears that physics do not apply to some manufacturers, or at least their marketing leads us to believe this is the case. Alas, the basic physics of sound and how materials relate to each other prevent these wonder products from achieving the ratings claimed by the companies marketing to unsuspecting consumers.
The basic facts are this: Without significant decoupling of the ceiling or wall, achieving extremely high levels of isolation will be somewhere between difficult and impossible. There are few exceptions for this, such as a four foot thick concrete wall, but if you had a wall that thick you probably would not be reading this. We suggest reading the following articles for a better understanding on how sound isolation products work, why certain products work, and how to maximize performance of various products or methods: