Starting from scratch-Acoustics Forum-Acoustic Fields Forum

So, I’m starting new house plans with a dedicated listening room . Dimensions are currently 23L x 17w x 9h. I can slope up the ceiling from 9 to 13 ft high in the rear. Most likely the floor will be concrete, but I could add a wood floor. The builder uses double wall construction for added insulation.
Would a square room with a flat 9 ft ceiling be easier to treat ?
Also I’m reading I should stay away from drywall. What other wall and ceiling approaches are recommended? Also do I need to specify the insulation within the walls
Would an all plywood or wood plank construction be a place to start, then measure the room and work from there?