tapestries and posters help with sound absorption?

The tapestry may help a little. Consider some framed, dense fiberglass (Owens Corning) covered with your choice of material. Colored burlap is the best choice. These fiberglass panels are 2' x 4' and available in 1" and 2" thicknesses.

Audiogoon,

I like your handle by the way. I rather doubt what I'm describing is meant for foundations. This would be used commercially for perhaps meat locker walls. I've been carting around three boxes of the stuff for 20 years. I can find no product description on the outside of the boxes. It was pretty pricey stuff at the time I purchased it but came highly recommended. I bought my current home shortly after buying this product. My dedicated room is very nice acoustically so I haven't bothered to use anything. I'm sure that it could be improved upon and I've of late been contemplating doing this as an experiment. If anyone knows a scientific way to approach this I'd sure like to know.