I’m building a vocal booth in a few months and had a few questions regarding the 4 corner beams: should they be the same size as the innerframing? Should the outer beams be bigger and/or a different material (than lumber)? I’ll be using roughly 2×2 inch lumber for the framing and place 2inch thick rockwool in the walls which will be covered by roughly 1/2 inch thick plywood on both sides. I’d appreciate any input on this!