Curtains that let sound through, but aren't transparent?

I'm going to have 4" thick broadband absorbers mounted on the wall to the right of my listening position, and to the left I have a large window that I have plugged with the same type of 4" thick absorbtion material. I would like to cover this plugged window with some sort of curtain for aesthetics. Does anyone know of a curtain material that will allow for relatively the same amount of absorbtion on both sides of the listening position? A curtain material that will let mid/high frequency sound through but still cover up the plugs well (not transparent)?

> Does anyone know of a curtain material that will allow for relatively the same amount of absorbtion on both sides of the listening position? < You might be overthinking this. If a curtain in front of an absorber panel absorbs a little more on its own, no harm is done. Just avoid shiny reflective fabrics. Any soft material that you can blow through without getting a hernia should be fine. You can test any fabric easily enough. Get a few small (12 inches square) swatches from a fabric store. First, hold a bare piece of rigid fiberglass or whatever right in front of your face and talk into it. It sounds like you're talking into a total void, right? Now put a piece of proposed fabric between you and the panel and see if it still sounds like a total void. If so, the fabric will work fine as a cover. --Ethan

Yeah, probably am over thinking it. Thanks for the response!