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Drapes? do they work for absorption?

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Drapes? do they work for absorption?

Postby Neil_kennedy » Wed May 04, 2005 3:46 pm

i have a large live room (about 26 x 16 foot) the walls are brick and very reflective, i want to know if hanging drapes the length and breadth of the room is going to "deaden" the room somewhat and reduce reflections? if so is there a particular material to use that is good for this?

any ideas? :?
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Re: Drapes? do they work for absorption?

Postby Ethan Winer » Wed May 04, 2005 4:45 pm

Neil,

> i want to know if hanging drapes the length and breadth of the room is going to "deaden" the room somewhat and reduce reflections? <

Yeah, somewhat, but ultimately drapes are not a good solution. The problem with drapes and other thin materials is they absorb only high frequencies. So you end up with a room that's dead sounding yet boomy at the same time.

All rooms need broadband absorption that's effective to as low a frequency as possible. The preferred material is rigid fiberglass (or rigid rock wool or mineral wool).

There's a lot of information in this forum, and in the SOS articles archives, and also in my Acoustics FAQ here:

www.ethanwiner.com/acoustics.html

That will keep you busy for a while. :)

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Re: Drapes? do they work for absorption?

Postby Savant » Wed May 04, 2005 5:44 pm

Neil,

To be useful absorbers, drapes need to be:

1. Heavy. Min 0.4 kg/m²; >0.6 kg/m² is best. (12-18 oz/yd is how it's usually denoted in the States.)
2. 100% or better "fullness". This means the drape should at least be 2:1 in terms of area of material:area of coverage.
3. Spaced at least 76mm (~3") from the wall.

As long as your drapes meet all three of the above, they will provide great absorption of reflections at ~250 Hz and above.

Best regards,

Jeff D. Szymanski
Chief Acoustical Engineer
Auralex Acoustics, Inc.
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Re: Drapes? do they work for absorption?

Postby Hugh Robjohns » Wed May 04, 2005 6:35 pm

Excellent specific recommendations there from Jeff. Basically, the drapes need to be as heavy and dense as possible, with a generous excess of material to give deep and fulsome pleats, and to be spaced a little away fromthe wall.

The usual failing is that people hang material which is too lightweight and not generous enough in length. Thats when only the high end gets abosrbed and the room ends up sounding boxy.

However, even with generous heavy, dense drapes, you'll probably still find the room gets a bit boomy and it would be worthwhile dealing with the low frequency standing waves, for which you will need some form of bass trapping. Etahn has already posted some useful links. You should also review the practical advice at www.studiotips.com, and on Jeff's company site, of course ;)

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Re: Drapes? do they work for absorption?

Postby Psychederick » Wed May 04, 2005 6:50 pm

What we've found very useful in our live room is theatre black. The on ly problem being that by nature of its colour it does make the space feel smaller.
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Re: Drapes? do they work for absorption?

Postby Savant » Wed May 04, 2005 7:27 pm

Thanks for the kind words and subtle plug, Hugh! ;) I should mention that I regurgitated some of the specifics from references I have on hand. Whenever we need drapes, we use or direct folks to Rosebrand. I don't know if that's a good link for UK folks - perhaps there's an equivalent company over there?

Also, it seems like eons ago that I took my college theater sound design course. Three walls of the recording room were treated with heavy velour curtains spaced about 3" or 4" from the wall. The floor was carpeted and the ceiling was acoustical ceiling tile. Add some gobos and the room was exceptional for recording dialog and foley.

Best regards,

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Auralex Acoustics, Inc.
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Re: Drapes? do they work for absorption?

Postby giles » Fri May 06, 2005 3:58 pm

This mostly seems to deal with reflections, i would like to know how effective heavy velour drapes would be in stopping sound leaving the room, not total soundproofing but a significant reduction?
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Re: Drapes? do they work for absorption?

Postby Ethan Winer » Fri May 06, 2005 6:37 pm

Giles,

> i would like to know how effective heavy velour drapes would be in stopping sound leaving the room <

Zero, zilch, nada.

Okay, maybe 0.01 dB at 100 Hz. :shock:

--Ethan
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Re: Drapes? do they work for absorption?

Postby giles » Fri May 06, 2005 7:20 pm

thanks Ethan, that's clear enough.
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Re: Drapes? do they work for absorption?

Postby Ric_westyorks » Fri May 06, 2005 10:09 pm

I have some acoustic absorption data for wool serge at work. I will post it when I am back at work next week.

Wool serge is used by acousticians where panels are not applicable. In the UK many theatre specialists re-sell it, One place that gets specified by the top Acoustics consultants that I know of is J & C Joels Ltd of Sowerby Bridge, West Yorkshire. Pleasant staff to talk to though wool serge is never cheap. I have seen this used where CBSO are based and in some other venues for absorption.
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Re: Drapes? do they work for absorption?

Postby giles » Sat May 07, 2005 8:17 pm

thanks for the Joel tip; interesting company; they don't give prices on the site. If it's not too much trouble those figures would be useful.
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Re: Drapes? do they work for absorption?

Postby bellay » Fri May 03, 2013 6:59 pm

Hi, I'm also searching for some curtains to cover window thats behin my speakers. On left/right/ I have absorption panels but I cant put one on my window. I bumped on this pretty cheap ikea curtains: http://www.ikea.com/us/en/catalog/products/40111987/
would this be ok for some mid/high absorption or I should go with heavy velvet curtains.
Thanks
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Re: Drapes? do they work for absorption?

Postby GIK Acoustics » Tue May 07, 2013 1:12 am

The window behind your speakers usually doesn't contribute to any major reflections so even a smaller thinner curtain should work well. Of course if you're looking to deaden the space more a thicker curtain would be warranted but is probably unnecessary on the front wall.
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Re: Drapes? do they work for absorption?

Postby Russell B » Tue May 07, 2013 10:07 am

Hi I am using Drapes in my studio as a room changer I suppose you'd call it I have one wall of one room with heavy drapes floor to ceiling and by opening and closing them I can change the character of that room from bright to warm depending on what I need at the time. It is not a large room but it is useful to be able to change the sound slightly but I will admit with them closed fully it can get a bit boomy depending on what I'm recording.
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Re: Drapes? do they work for absorption?

Postby quietcurtains » Thu Sep 13, 2018 6:39 pm

I think Ethan and Jeff mentioned the main technical points.

Not many curtains have been tested for STC and NRC values, but there are a few companies that have.

We do have some data for both sound proofing and sound absorbing curtains at
https://www.acoustic-curtains.com/lab-tests/
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Re: Drapes? do they work for absorption?

Postby blinddrew » Fri Sep 14, 2018 1:12 pm

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