I have an argument that I would like to have settled. In another forum, the original poster asked a general question as to why there was what appeared to be cotton stuffing inside his speaker box. Here are some excerpts that were posted in response by the person I'm in disagreeance with: “It is MOST often referenced to as Poly-fill. It is NOT cotton. Cotton would provide the exact OPPOSITE of what (and why) you are wanting to "fill" your box.” “As a Mater of fact the ONLY thing adding a loose fibrous material does is convert the "pressure" to heat.” “As far as the quantity to use... 1 to 1.5 lbs of polyfill per cubic foot volume of the enclosure. It is NOT an exact art, but the benefit is about 25-30% increase in perceived volume.” So here we have three statements that to me appear to be somewhat absurd; First of all that although cotton filler is also a loose fibrous material it would have properties contrary to this polyester filler. Secondly that it is able to convert air pressure into heat. And third that by reducing the air volume by filling it with a denser material that you are in fact increasing the "perceived" volume. Just so you understand more about the necessity for a certain amount of cubic volume for a speaker box all you have to do is understand that the combined surface area of the speaker and throw (which is the distance it is capable of moving in and out) displace a certain amount of air space and that this creates a certain amount of pressure that causes the speakers itself to have to do more work in order to function the smaller the enclosure. I believe most 12” subwoofer manufactures suggest about 1’-1.5’ cubic volume. People believe you should use polyfill in situations where the cubic volume is less that this suggested amount and that it will make up for it. I’ll briefly explain my perspective. It would appear that this polyfill is actually just a dampening material. She is saying that it is not and that it only converts air pressure into heat. I’m not denying that in dampening that there is some heat, although I’m quite sure that if I were to attempt to measure it that it would be undetectable. I hope this is the right forum, and that I have included enough information for this to be settled.