Actually, my neighbors are not below but next door to me. Perhaps the fact that we're sharing the same joists caused the problem? The physical structure would have to be analyzed to find the specific parameters that are involved in your situation. But I have generalized the situation and what is typical. I suppose that's why the performace\ studio room where I work was constructed as a concrete slab "floating" a few inches above the rest of the second floor of the building (Don't ask me how it was made because I didn't get the details but it cost a ridiculous amount of scratch). Such floating systems are typical for broadband acoustic isolation applications. Is the entire room(all walls, celing, etc.) also decoupled from the rest of the building? This is what I would expect as well. -Chris
