Bad build but still trying-3/4" plywood on top or below?-Acoustics Forum-Acoustic Fields Forum

My room is the example of what not to do; 2×4 studs, low ceiling, etc. But I have been making the best of it and it does keep getting better, at least.

My roof is 2×6 studs with one layer of CDX 3/4″ plywood on top. (So the 2×6 studs are exposed inside my room)
I acquired some really heavy 3/4″ birch plywood at a great price.

I want to add a layer to my roof.

SHOULD I ATTACH THE 2ND LAYER OF PLYWOOD ON TOP OF THE DIRECTLY TO THE CURRENT LAYER OR TO THE STUDS INSIDE OF ROOM?

So then my room would have a flat very reflective ceiling that I can treat of course, and be 6′ lower too :(

(I currently have the space in between the studs treated and covered with a dense tapestry and this was very effective to stop the ‘pinging’ delay anomalies that were happening initially.)

Your advice is greatly appreaciated. This project is on hold until then…
Thank you
Leticia