For the record, wool acts quite differently than fiberglas, as does polyester fiberfill or spun mineral wool, especially in transition to the deep bass. Final placement and voicing of damping was always made by results. Listen to it, and if you have the means, measure the output smoothness. Insulation schemes will unload at various frequencies due to complex resonant behavior, especially in reflex systems. Fiberglas behaves more simply and predictably than any other scheme we found.
In my time, and possibly onward, the first reflection of the midrange driver off its rear enclosure wall was absorbed with dense pure wool felt - it worked the best for that purpose and its considerable expense was worthwhile. Our evaluation of wool batting for absorption was not as good as fiberglas.
