I've done quite a few studio builds, and keep on learning - sadly from my mistakes. I've discovered that lots of effort put into walls and floors is often wasted, because the roof and inner ceiling is where getting the same mass becomes a problem. In one of the past ones, I increased the ceiling thickness to match the walls, and the outside to inside noise transfer was really, really good. After 3 months, however, my lack of engineering design meant it had started to sag - so I cut out a big section in the middle, and got a so called isolation mount. This was really a screw bottle design with a big rubber section to "provide the acoustic isolation". Rubbish - it took the strain, and the sag was solved. Trouble was the first time a seagull landed on the roof, the walking around was transmitted loud and clear into the room. I bought some of the popular design books and pinched ideas from there for my next design, and from what I can tell, the isolation I get from the current ceilings is very similar to the walls. I do know that it would NOT be sufficient if I had aircraft near me. There are loads and loads of amateur designers, like me - and very few skilled in studio construction who will be local. There are designers who can from a distance, design something you or a builder can produce a specific product with accurate performance specs. My knowledge has been built up from my successes and my failures. So to a large degree, luck based on experience. I'd never want to do it for somebody else who's expectations I probably could not meet.
