I have always thought that the best covering is no covering for acoustic substance behind it. So the best acoustic covering is an acoustically porous one. Isn't that why they use burlap? I just don't see how any fabric/wallpaper would absorb anything on it's own given it's thinness. It could reflect, however, and that is not a good thing unless it's covering a diffuser.
Now, can you link me to the acoustic fabric site?