From an aesthetics point of view, I don't know that I would use different fabrics. Are you asking about the crown behind your screen or the crown above it?
If it was me, I would be looking at covering the wall behind your screen anyway with some sort of absorptive material. You could use that opportunity to mask the crown behind your screen. Alternatively, you could fill the empty area in the top panel with cardboard or foam insulation to prevent light reflecting through.
Is it solipsistic in here, or is it just me?