An Anechoic Chamber for SPCR

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UltraTouch, mentioned earlier, is a replacement for fiberglass batting insulation made almost entirely of recycled natural denim and cotton fibers. Its acoustic properties are not that well documented, but it's promoted as being better than fiberglass. Cotton was an acoustic insulation long before fiberglass came along, and it's still used sometimes for that application. Many of the consulted acoustics pros use it regularly; one called it Blue Fill.

Some 700 pounds of UltraTouch was ordered from a local distributor in Abbotsford at a cost of about $2,000 and delivered via truck to the back lane. There were 15 bags, each containing 10 pieces of 48" x 16" x 8" batting. They filled one side of the two-car garage. It has a thermal insulation value of R30. Fiberglass batts of the same R-value are usually 9.5" thick.

700 lbs of UltraTouch filled half the 2-car garage.

Initially, the plan was to just stack them up against the walls in the room, suspend a layer across the ceiling on a net of clothesline wire, then do a quick check of external noise transmission. The work on the ceiling was tedious, but successful in the end. It took a couple of days complete, what with the usual multiple trips to hardware stores for parts that were not anticipated or not purchased in large enough quantity. Some 200' of clothesline wire was used, for example — much more than originally anticipated. The wires had to hold well over 100 pounds, so it was important to screw large hooks into studs, not just the drywall, which meant locating and drilling into the studs. Sounds easy, but with interior walls in a house that's probably been slapped together at minimal cost, studs are harder to find than you'd think.

View of blue fill suspended a few inches below ceiling on mesh of clothesline wire. The air gap helps reduce sound transmission. Note batting on open door on right.

It wasn't simple to line the batts against the walls, either. Stacking them just to try them, as originally intended, two problems immediately emerged: They compress, which means more than 20 were need to reach the ceiling, and there weren't enough batts to cover the walls and the ceiling. Secondly, the batts are far too soft to be stable in such a stack. Wobble, wobble, tumble.

A compressed and wobbly stack of UltraTouch batts.

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