Acoustic panels

Hey Brian, I did the same in an old bedroom that had terrible slapback with my son's 4 piece band. I put panels on the walls with rockwool in them & fabric covers - I wouldn't recommend using rockwool from a health point of view - Tontine & other companies do a synthetic noise reducing batt that you can get at hardwares which works almost as well and has no health risks that the fibreglass & rockwool have. If you're painting the front, I think it needs to be a bit breathable to get the benefit of the attenuation across all the frequencies.

The other thing I did was build bass blockers into the corners - triangular columns of rockwool about a foot wide, with foil & fabric covering them. Its worked really well for 10 years & my son does a lot of high quality recording in there now. Let me know if you want more details on any of this or if you've already got the design covered.

I'm no sound engineer & this is pretty basic, but its worked quite well. I'm sure there are better experts on this forum that can offer more advice.

Cheers, Tim

 

2" Owens-Corning 703 fiberglass board is the industry standard for sound absorption. A 6 pack of 2' x 4' panels runs about $70 - $80. You'll need to wrap fabric around them to keep fiberglass particles out of your skin & lungs.

 

I'd suggest going to 1X4"s instead, and use standard fiber glass batts. You might try to find fiber fill instead. Our main theater (6,000 seats) had a real problem with slap back. Diffusers (3/8 round 2, 3, &4' widths) helped. As it was built in the late '30s, there was asbestos panels , tho they were encapsulated. For absorption, there are perf board panels with fiber glass behind them. Make sure the floor is carpeted, and consider heavy velour curtains on some of the walls. An irregular shaped room might help as well. There are three basic types of surfaces---reflective, absorptive, and dispersive. A mixture of all three is what you want, tho finding a happy balance is the hard part.

 

R21 rolls would fit inside 1x4s, but as they are much less dense than 703, they will absorb mostly just higher frequencies. It works, but 703 gives a better balance of absorption across a wider frequency range.
Definitely a blend of reflection, absorption, & dispersion is needed, though in smaller rooms absorption will take on more importance than the other two parameters.

 

Nothing absorbs sound like an audience in winter clothes.

 

Look into creating something that'll allow you an air gap between the panel and the reflective surface for optimum performance. I've got a mix of foam treatment and bass traps with the foam attached directly to the walls while the bass traps are suspended or mounted to take advantage of having that gap. Check out ATS Acoustics. They've got the best prices for finished panels that I've found anywhere if you want to just order direct but they also a ton of DIY materials along with the specs of the different materials. I bought some traps from them and my wife bought some DIY stuff for a project for her studio space. They were great to deal with and we're both very happy with what we got from them. Plus, if you peruse their offerings, it might inspire your design.

As far as materials, you'll want to know the acoustic properties of your options. My wife ordered Knauf ECOSE for her panels and they turned out great. I used Rockwool for some that I made years ago with coffee bean bags from our local coffee shop. I believe there's also some cotton material but again, it's all about the acoustic performance.

And don't discount diffusion as an option. Creating random, non-parallel lines in the space can help tame it as well.

 

Ironically, I won an Auralex Starter Kit last month. It augments my space but due to the strange layout of the room (it's an attic space with an A frame ceiling), I had to work to put it to use. There's other foam options, when I first treated the room 15 years ago, I found some bulk egg crate foam for dirt cheap. It held up but the Auralex foam does seem to be higher quality. It's a rabbit hole but it's worth getting a good understanding about how to treat your space before you begin. And here's an article on DIY diffusers.

 

No matter what material you use, make sure it's fire[proof. Remember Whitesnake.

 

I once had the opportunity to tour an acoustic anechoic chamber used for noise testing for a manufacturing firm. It was really strange to stand alone in there; I swear I could hear the blood flowing through my veins. It would have been interesting to play music in it.

 

Yeah, I knew it was White something or other. Still, the point is, make sure nothing's flammable.

 

Yeah, it was Great White. However, their issue with the fire wasn't that they didn't have fireproof acoustic panels and some accidental spark. The issue was the result of them using pyrotechnics in a building/venue that wasn't designed for it. I remember seeing video and the sparks shot right out onto the back wall, igniting the banner or whatever was hanging behind them. It then engulfed the wall and raged thru the room.

 

The acoustic panels had been painted over as I remember, compromising any fire retardant. Using pyro in such a tight enclosed space on top of that was just a chain of mistakes that never should've happened. Having worked in a major university, we dealt with the fire marshal on a daily basis. When you're dealing with the public, you can never be too safe.

 

IIRC what was on the back wall was some sort of foam sound absorber material.

 

It definitely could have been. But whatever was on the back wall wouldn't have mattered because those pyrotechnics also engulfed the ceiling too.