My shop has a loft connected to one side that's about 8ft tall. I think what i'll do is make a hallow wall made with studs and plywood, with about 6'' of insulation stuffed inside of it. then move those around the compressor which is placed in the very corner of the shop. Think of it like a welding shield that welders put up that makes it so people nearby don't hurt their eyes, only in this case it's from noise.