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Author Topic: Acoustical treatment options  (Read 2896 times)

Aaron Tyree

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Acoustical treatment options
« on: July 18, 2011, 02:57:39 pm »

Hey all I am a youth minister and I have a very live youth room. There is little to no acoustical treatment in the room at all. I have fiberglass panels that the previous youth minister bought but they are just the raw material. My question is can I use something to cover them so I can hang them in the room?

I guess they were not used before because they were wrapped in burlap and the fire marshal said they could not be hung because they were flammable. The room is 30' tall, 40' deep and 90' wide (approx. dimensions). Thanks
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Brad Weber

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Re: Acoustical treatment options
« Reply #1 on: July 18, 2011, 04:25:35 pm »

Hey all I am a youth minister and I have a very live youth room. There is little to no acoustical treatment in the room at all. I have fiberglass panels that the previous youth minister bought but they are just the raw material. My question is can I use something to cover them so I can hang them in the room?

I guess they were not used before because they were wrapped in burlap and the fire marshal said they could not be hung because they were flammable. The room is 30' tall, 40' deep and 90' wide (approx. dimensions). Thanks
I would probably avoid putting something over the existing finish as the acoustical properties of the panels would likely be reduced, but the first step might be to ask the same question of the Fire Marshal, would he accept them if the burlap were removed and they were covered with a properly rated fabric?  If they will accept that option then the next aspects might be what material would be viable and what are the most effective locations for the panels?  If not then it seems to make little sense to pursue the idea.
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g'bye, Dick Rees

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Re: Acoustical treatment options
« Reply #2 on: July 18, 2011, 04:55:09 pm »

Besides looking at treatments you should make sure that whatever sound source(s) you have are focused AMAP on the desired listening area, keeping the sound energy from being reflected off of any adjacent planes/surfaces.  It is the complexity of the reflections which jumble things and reduce the clarity and intelligibility of the room sound.

Beyond absorption you should also think of diffusing the sound.  Flat panels of non-reflective materials can help at the walls, but oddly patterned, curved or sculpted shapes within the listening space can also be effective.

Good luck.  And listen to Brad.......he's a real pro.
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Brian Ehlers

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Re: Acoustical treatment options
« Reply #3 on: July 18, 2011, 06:22:46 pm »

Before considering the covering, please describe the panels in more detail.  Manufacturer and model number?  Thickness?  You want to make sure they're worth hanging before you go to the effort.  And how many square feet of panels do you have?

The space you've described is basically a gymnasium.  Like Dick said, it may need more help than the panels provide.
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Aaron Tyree

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Re: Acoustical treatment options
« Reply #4 on: July 19, 2011, 02:37:52 pm »

Before considering the covering, please describe the panels in more detail.  Manufacturer and model number?  Thickness?  You want to make sure they're worth hanging before you go to the effort.  And how many square feet of panels do you have?

The space you've described is basically a gymnasium.  Like Dick said, it may need more help than the panels provide.

Thanks for the help. Here is a couple of picture of the space and of the fiberglass panels.



(I hope these work)

Yea the room is almost a gymnasium. Right now there is a thick curtain behind the stage and on the back wall and that is all the treatment that is in the room. The wall behind the stage is 4 sheets thick drywall and the other side is a solid concrete wall. The curtains are the only thing there.

The panels are Knauf Insulation board 6.0# and is product code 2506. I dont know if that helps they are 4' x 2' and have 2 different thicknesses 2" and 4". I have 93 of the 2" and 88 of the 4". So that would be 1384 square feet.

I am getting ready to change the speak placement I think and try to move them as close to the audience as I can to keep the sound down as much as I can. They are EAW JF200e and I think I will try to fly them at the front edge of the stage. I am hoping between that and putting the panels on the back wall it will make the room not so live.

Is that what I should be doing? I know we dont have much of a budget.
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g'bye, Dick Rees

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Re: Acoustical treatment options
« Reply #5 on: July 19, 2011, 03:00:05 pm »

In any enclosed space the intelligibility is most affected by the amount of direct sound the listener receives.  Once the percentage of reflected or reverberative sound increases at the listening position, intelligibility goes down.  The varying arrival times of the different sound paths adds up to mud. So......

Speaker placement for proper coverage is the first thing to consider.  Focus the sound on the listeners.  But consider also that the PA sound and the sound of any "stage wash" from amps and monitors are separate sources both in position and TIME.  Though the sound(s) may be the same, the arrival times are different due to the different paths.

Getting the stage sound under control thus ranks up there with any speaker choice/placement/sound treatments.  It's not just a matter of some panels here and there, but the total sound picture from source(s) to listeners.  Everything is integrated from the players, instruments, stage positioning, stage sound.......the whole 9 yards.

It takes a lot of experience to sort out the various parameters and to balance them all.  It is not simply a matter of equipment, but total integration of all components from the musicians to the listeners, the equipment in between and the enclosing environment.

Putting up sound panels will do little to change the result of complex multiple sound sources in a large room.  You have to get the sound to be as coherent as possible first.

Balance.
« Last Edit: July 19, 2011, 03:32:23 pm by dick rees »
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Aaron Tyree

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Re: Acoustical treatment options
« Reply #6 on: July 19, 2011, 04:01:57 pm »

The Fire Marshal is good with the properly rated fabric. A member of the church said I could use bed sheets because they are fire retardant. Would that work?

Stage sound is not an issue. I put an in-ear system in place with a couple headphone amps so there is not much stage sound. I also have a professional sound company coming to suggest where to put the speakers.

I figure the panels will help and I have them just laying in storage. I just need to know if I can use them and where to put them?
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g'bye, Dick Rees

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Re: Acoustical treatment options
« Reply #7 on: July 19, 2011, 04:07:10 pm »

The Fire Marshal is good with the properly rated fabric. A member of the church said I could use bed sheets because they are fire retardant. Would that work?

Stage sound is not an issue. I put an in-ear system in place with a couple headphone amps so there is not much stage sound. I also have a professional sound company coming to suggest where to put the speakers.

I figure the panels will help and I have them just laying in storage. I just need to know if I can use them and where to put them?

Sounds like you've got the stage volume under control.  So we can go back to aiming the sound at the listeners and keeping it off the back wall.  With such a shallow and wide space the likely candidate is slap-back off the back wall.  Just keeping the sound off of it in the first place will likely solve the better part of the problem.  After that some panels on the back wall should help.  Remember also that putting some contours into the formula will also assist.  Anything you can do to break up any large, flat planes will be helpful without relying solely on absorption/damping.

Edit:

link to "shapes"

http://www.google.com/search?tbm=isch&hl=en&source=hp&biw=1280&bih=685&q=sound+baffles&gbv=2&oq=sound+baffles&aq=f&aqi=&aql=&gs_sm=e&gs_upl=1152l5034l0l5483l13l13l0l3l3l0l320l2326l0.4.5.1l10

PS

A "member of the Church" is not qualified to advise you on the flammability issue.  The Fire Marshall is.  Ask the Marshall.
« Last Edit: July 19, 2011, 05:18:23 pm by dick rees »
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Brad Weber

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Re: Acoustical treatment options
« Reply #8 on: July 20, 2011, 07:09:42 am »

The Fire Marshal is good with the properly rated fabric. A member of the church said I could use bed sheets because they are fire retardant. Would that work?

Stage sound is not an issue. I put an in-ear system in place with a couple headphone amps so there is not much stage sound. I also have a professional sound company coming to suggest where to put the speakers.

I figure the panels will help and I have them just laying in storage. I just need to know if I can use them and where to put them?
I won't say absolutely no, but I doubt it.  From an acoustical perspective, the fabric covering the panels needs to be 'acoustically transparent' in order to get the most effectiveness from the panels, which typically means a more open weave fabric.  While far from scientific, a quick check is to hold a layer of the material over your mouth and try to breathe through it (or if you smoke, try to blow smoke through it).  If you have difficulty with that then it is probably not a good material choice for acoustical panels.  Even more important is that materials for 'public assembly' spaces typically do not need to just be 'fire retardant, they are usually required by code to meet specific ratings from vertical flame spread and smoke issued tests, usually Call A or Class 1 ratings.  If a material does not meet either of these requirements, especially the life safety ratings, then it should probably be avoided.
 
There may also be some practical issues with both the construction and the locations of the panel.  For example, it appears that what you have are simply 2'x4' pieces of 6pcf fiberglass board. Because they do not have reinforced edges or integrated mounting points/clips or anything else, aspects such as getting clean corners with the fabric, securely mounting them, avoiding damage to the edges and corners, etc. may be challenging.  Manufactured panels would typically have resin reinforced edges and mounting points or aluminum or plastic frames to address these issues while DIY panels might typically have wood frames.
 
The location issue could factor in as acoustical panels are often most effective when installed at ear level, say from 3' to 7' above the floor to accommodate people seated or standing.  However, that also puts them at a level where the depth and exposed edges may cause some practical issues.  And while putting the panels on 'sleepers' or wood strips behind them increases the apparent thickness and thus improves the low frequency absorption of the panels, that would amplify any such concerns.
 
What may be becoming apparent is that to get effective acoustical results in a safe and aesthetically acceptable manner is something you can probably do but it is likely going to involve more than simply wrapping the fiberglass boards you have with the cheapest fabric you can find.
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