The simple answer is it isn't simple experimentation trumps theory in my view.
In theory, ideal is;
Height:Width:Length
1:1.6 :2.33
which suggests you should make your room 6.2 Meters long and if you placed large acoustic panels (such as Realtraps, GIK etc.) on the ceiling to bring ceiling down 20 cm you may get the ideal dimension.
Decoupling is good up to a point as it helps keeps the noise down for neighbouring rooms. However, you really want sound energy to dissipate and not remain trapped reverbing in your room...so too much decoupling may actually be bad (imagine the floor floating like the membrane of a drum = very bad). Absorption or damping is just as important as decoupling....heavy damped rubbery material between floor and joists with lots of glue to make sure nothing is loose.
In practice, theory never works and you should probably consider seeking advice from an expert who has doen many installs and has learned first hand what does and does not work.
In theory, ideal is;
Height:Width:Length
1:1.6 :2.33
which suggests you should make your room 6.2 Meters long and if you placed large acoustic panels (such as Realtraps, GIK etc.) on the ceiling to bring ceiling down 20 cm you may get the ideal dimension.
Decoupling is good up to a point as it helps keeps the noise down for neighbouring rooms. However, you really want sound energy to dissipate and not remain trapped reverbing in your room...so too much decoupling may actually be bad (imagine the floor floating like the membrane of a drum = very bad). Absorption or damping is just as important as decoupling....heavy damped rubbery material between floor and joists with lots of glue to make sure nothing is loose.
In practice, theory never works and you should probably consider seeking advice from an expert who has doen many installs and has learned first hand what does and does not work.