I am building a sound proof room to run a dynamometer. The room is inside a concrete block building with a 10' ceiling and wood trussed roof.

The big issue, there are two residential garage doors on either end of the 20' W x 40' L room. I need to insulate the doors and make them as air tight as possible with gaskets, but I'm still afraid I'll only be able to achieve an STC rating of something like 20, most of my walls will be in the 55-65 STC range, and I need my doors to be at least 40 STC.

Only one of the 16'w x 8'h garage doors concerns me, as the other one is facing towards a direction that noise won't concern me much.

I have thought about installing a commercial roll up door on the outside of the building, but those things are not air tight and even the insulated ones have very little R value (more insulation = more noise reduction and higher STC rating, to some extent).

Thoughts? maybe build some type of multi piece door that swings side to side or up and down on hinges? and that I can gaskets around the edges to reduce noise transmission.