Home » R/E/P » Francis Manzella » Meeting hall sound absorption
| Meeting hall sound absorption [message #332672] |
Fri, 11 April 2008 12:17  |
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 garret
Messages: 822
Registered: November 2004
Location: Champaign, IL |
Gold Member |
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Greetings, folks. I've volunteered myself again.   I'm helping a local church deal with a noisy meeting hall. The space has so many reflective surfaces, it's almost impossible to carry on a conversation in there even if you only have two dozen people present. When you fill it to capacity (200 or so), it's downright painful.
They have a modest budget ($3000-5000), which should be enough to do the job, but probably isn't enough to pay for an acoustics consultant from Chicago or St Louis to travel here and come up with a plan (there's no one local).
I figure they just need some rigid fiberglass panels, wrapped in fireproof fabric, on the ceiling. But I could use help figuring out exactly how much of the ceiling to cover, what materials to use, and how to attach the panels.
Here are some photos:
http://www.worksongs.net/photos/2008-03-UU/
And some basics about the room:
-- The room is 50 feet by 40 feet, with 12 foot ceilings.
-- The floor is hard, shiny, linoleum. For maintenance reasons, they don't want to carpet the floor, although I'm sure that would help the noise problems.
-- They'd like to maintain the aesthetics as much as possible...
-- The ceiling is painted hardwood. It's a beautiful old space, with the big beams and the woodwork... but there are no absorptive surfaces whatsoever.
-- One side of the room is bay windows, the other is open to a hallway... on the other two sides about a third of the wall surface is doorways, and the other 2/3 is plaster walls, bulletin boards, etc. It would be hard to find a place for sound treatment on the walls...
-- The ceiling is divided into six or seven bays by big exposed beams. In each bay there are two hanging pendant lights, with surface mounted electric wiring (in conduit.)
-- Big ventilation ducts run along the long sides of the room, at the ceiling level.
Some questions...
1) Do you agree that adding some fiberglass panels on the ceiling is the most cost-effective solution? They are also considering acoustic tiling.. but the surface mounted wiring makes that tricky... they'd have to put in drop ceiling which would look awful. They were also considering acoustic paints, but I figure those would be of marginal effectiveness.
2) How much of the ceiling surface area should be covered? I don't want to deaden the room too much, but I figure it would still be a lively room even if they covered the whole ceiling, what with the floor being so reflective.
3) Is it okay to mount DIY fabric wrapped rigid fiberglass panels on a ceiling? I don't want to have fiberglass fibers or dust fall out... I've only used that kind of panel on walls where it seems to be fine. Would it be better to use rockwool or another non-fiberglass product? Or an encapsulated commercial product designed for ceiling use?
4) If panels are the thing.. how would you go about making them and mounting them on the ceiling? Or is there a commercial product you would recommend?
Thanks for the help!
-Garret
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| Re: Meeting hall sound absorption [message #332733 is a reply to message #332672 ] |
Fri, 11 April 2008 14:34  |
Steve Hudson
Messages: 482
Registered: November 2004
Location: Austin, Texas USofA |
Active Member |
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You could hang 4'x2' fabric-wrapped 703 "clouds" using eye hooks and washers with short lengths of chain to suspend them to the ceiling. I did this in my last two tracking rooms. They can hang 4"-6" off the ceiling and improve their efficiency. Stagger them as you must because of the configuration of the beams and light fixtures. The only way to know "how many?" is to install a bunch and see how the room responds.
"The music business is a cruel and shallow money trench, a long plastic hallway where thieves and pimps run free, and good men die like dogs. There's also a negative side."
- Hunter S. Thompson
http://www.myspace.com/steventoddhudson
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| Re: Meeting hall sound absorption [message #333807 is a reply to message #332672 ] |
Tue, 15 April 2008 14:43 |
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garret
Messages: 822
Registered: November 2004
Location: Champaign, IL |
Gold Member |
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Thanks for the ideas, everyone. I know this is a low brow situation for a high end forum... I appreciate your input.
The church will probably have the work done by a local carpenter who has built and installed acoustic treatment panels before (for the Gene Siskel theater in Chicago, among other projects...) He's not an acoustician, however, so I'm trying to help out a bit.
I'm intrigued by how much diffusion you have in your design, Glen. This is a very loud room.... ugly sounding too, with tons of flutter echo. (The ceiling is flat, the floor is hard and shiny, and the walls are square. Oh, and the bay windows at one end reflect a lot of high end...) So I can see how diffusion would help to make it a better space, particularly for music events.
The room is painfully loud when it's at capacity (200 people or so). I forgot to bring my db meter over the other day, but I'll go back this weekend. I did a few test recordings, comparing the ambient noise with no one in the room, with two dozen people, and with 100 or so people.
I've attached the spectral comparison... the bottom line is the ambient baseline, the middle is w/ two dozen people, and the top line is the crowded state.
Somewhere on the net, I found a rule-of-thumb for how much absorption to add to a room... you take the cubic volume of the room in feet, and multiply by 0.03 or 0.04 and you get the sq footage of absorptive material to add.
That works out to 600-800 sq. ft for this room. I found an insulation supplier in Chicago who can sell us the material at a decent price, and wood for frames and fabric (guilford of maine) is affordable... so it looks doable in the budget if we get some volunteer labor from church members.
An option we are considering is to hang three large panels in each bay... 4 x 8 foot, 2' thick fiberglass with frames + fabric covers. That would be 96 sq feet of absorption per bay. The bays are 40 feet by 7 feet wide, so we're talking about covering 35% of the ceiling.
I'm sure it would be better to distribute small panels on the ceiling evenly throughout the room... but I'd think the labor to build and install 90 panels would be significant. Making 21 larger panels should be more manageable.
A second area we are thinking of treating is the "pockets" at the end of each bay, along the wall. I think you can see what I mean in this picture...
http://www.worksongs.net/photos/2008-03-UU/slides/IMG_5732.h tml
Those pockets (between the hvac duct and the ceiling) are 2 ft high by 7ft wide by 2ft deep... and run the perimeter of the room. I'd expect adding some material there would do some good, and be aesthetically invisible.
Curtains are also in the long-term plans.. but they are a lot harder to get approved by the church committees... too many color choices! With acoustic treatments we can just go with a neutral that blends in with the walls/ceiling, and avoid the arguments. 
-Garret
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| Re: Meeting hall sound absorption [message #334648 is a reply to message #332672 ] |
Fri, 18 April 2008 10:31 |
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garret
Messages: 822
Registered: November 2004
Location: Champaign, IL |
Gold Member |
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I checked with the church budget committee, and it looks like $5k is it for this phase. So I guess we'll split this up and plan some things now that can fit in the budget, and some for the future when more money is available.
I'm thinking we treat the ceiling now for sure.
Then either do the wall pockets, or add curtains in various places... Curtains are a headache to get approved because of color choices, but they might do more good than treating those wall pockets...hmm.
Thanks again for your help.
I'm just so glad I could give them some solutions other than cheap wall-to-wall carpet, popcorn paint, and drop ceilings... That's the kind of stuff they were considering before I nosed into the planning meetings. Oh, and hanging up old quilts. Flammable, mismatched, donated quilts, stapled to the ceiling.. ugh...
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| Re: Meeting hall sound absorption [message #334761 is a reply to message #334648 ] |
Fri, 18 April 2008 17:22 |
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rankus
Messages: 3768
Registered: March 2005
Location: Vancouver Canada |
Platinum Member |
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What about some simple hanging cloth banners?
Rick Welin - Clark Drive Studios www.hellfirerecords.com
"Make it count." ~ T Manning
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