If you're serious about listening to music at home, either as a producer or a consumer, you are probably interested in including some acoustic treatment in your listening room. Bass traps in the corners and broadband absorbers along the walls are commonly the first pieces of acoustic treatment employed. But what is this stuff made out of, and is it okay to have in your home?
Most acoustic treatment on the market today is made out of some sort mineral wool insulation product (either fiberglass-based or stone-based), typically enclosed in a wooden frame and covered with an acoustically-transparent fabric. Mineral wool is well-regarded as being perfectly safe... when used as intended by the manufacturer. We have this stuff in our homes, sealed up in the walls; it was never designed to be hanging on the walls in our living space.
People who are concerned about keeping chunks of mineral wool insulation in their living spaces are typically concerned about one or both of:
- Is the product carcinogenic?
- Are airborne mineral wool fibers getting into your lungs?
As of this writing, the current official statement is that none of the products from the big names in insulation used for sound absorption -- neither from Owens Corning, Rockwool, nor Knauf -- are considered carcinogenic. There is no documented evidence that handling or inhaling these insulation products -- especially in the limited degree associated with using them for sound absorption -- would put anyone at risk. With the (supposed) exception of Knauf ECOSE insulation, all of these insulation products are manufactured with a small amount of formaldehyde, but this is "baked" off during the manufacturing process, leaving only a negligible amount in the end.
That's encouraging! But if you spend much time around mineral wool insulation, you still might wonder about breathing in mineral wool fibers or dust. The good news there is that inhaling small amounts of mineral wool fibers may be annoying, but should not pose any long-term health threat.
This all makes pretty decent sense. Mineral wool insulation has been used in professional recording studios for decades. If it was a serious problem, surely there would be outcry.
Nevertheless, even assuming that there is no known health risk to the insulation fibers, I wasn't sure that I liked the idea of having them around my home studio space. And even if there is no known health risk to any chemical content of the insulation, it turned out that most of the sheets of Rockwool Rockboard 60 that I purchased gave off a chemical odor that I didn't like smelling while in the studio.
So if not using mineral wool, what other options even exist? My own research eventually led me to Hofa-Akustik in Germany, which offers (among other things) broadband absorbers made with Basotect melanine foam, and bass trapsmade with natural sheep wool. I placed a small initial order to evaluate their products first-hand, but information available online suggests that Basotect is an unusually high-performing acoustic foam, and that sheep wool is works surprisingly well as a low-frequency sound absorber. I am looking forward to high-performing products that avoid the concerns associated with mineral wool fibers.