Limp vs Rigid Sound Barrier

Hello, I'd like to know if people have experience or opinions of the difference between using a limp barrier material, like Acoustilead, Acoustiblock, Sheetblok or Acoustiseal vs. a more rigid sound deadening board like Acoustiboard or Celotex? I am looking for opinions in regards to floating walls and floating floors. Thanks!

It is possible to distill walls down to two basic categories - coupled and decoupled. A coupled wall would be a single wood stud wall, where a rigid member attaches the two sides. The rigidity of the wood stud lets vibration transmit fairly freely from one side of the wall to the other. Any other wall with two leaves and rigid connectiosn between them would also fall into the "coupled" category. Single steel studs of 20 gauge or thicker fall into this category. In this type of assembly, the location of the primary low-freq resonance is primarily a function of stiffness (panel stiffness and stud spacing). A decoupled wall is a wall where there is no connection, or a flexible connection, between the two sides of the wall. resilient channel, sound clips, double studs, staggered studs = these are the common forms of decoupled walls. In this type of assembly, the location of the primary low-freq resonance is primarily a functino of the weight on each side of the wall and how deep the cavity is, with resilient channel walls taking a penalty due to the nature of the channel and showing a higher resonance. A single 25 gauge (flexible) steel stud wall exhibits the traits of both categories and is an interesting thing to study. But my point is this: in a decoupled wall, lowering the frequency at which the primary resonance occurs is the most important thing, and using MLV or soundboard in such a wall isn't a great idea because neither of them is nearly as heavy as a cheaper layer of 5/8" drywall, and with the extra weight of the drywall comes lower resonance and better low-frequency isolation. in a single stud wall, neither soundboard or MLV can give enough performance to make it go from mediocre to great, and neither really outperforms just adding more drywall. Attached data illustrates and is taken from tests run in a NVLAP certified lab. In addition to being a comparison of TL measurements, the compared data in these graphs shows comparisons made on the same frames, same insulation, etc. (literally thes ame frame, not removed from the test opening but simply having panels changed).

if that was too much blabber, i would simply say that for any wall - especially a decoupled wall where the low weight of these things will be a substantial penalty - just use more drywall. Spend the $$$ on some extra studs, make a staggered stud wall with as many alyers of drywall as you can afford to put on (which is quite a few for the cost of MLV).