Acoustic Properties of Thick Velvet - AVS Forum
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post #1 of 9 Old 02-11-2007, 06:06 AM - Thread Starter
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I am finishing the tape and mud of my HT. Currently I am thinking through acoustic treatments for the room.

I know where & how most recommend acoustic treatments with linacoustic, bass traps, first reflections, etc. My question however has a slight twist....

Rather than using acoustic panels wrapped in acoustically transparent material up to ear height on the side walls, I am considering hollow panels wrapped in HEAVY velvet material. This material did not pass the "blown air" test. I am assuming this will perform well for the absoption of highs and mids and I would still need to address the bass traps seperately.

Why am I considering this? I have a sliding glass door in the rear of the room that has this velvet as a curtain with black-out cloth sewn onto it. I would like to maintain the use of it throughout the room rather than a GOM selection that might not maintain the same look.

Thoughts?

Thanks in advance.
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post #2 of 9 Old 02-11-2007, 06:59 AM
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I don't think the velvet will allow for enough absorption of high frequencies.
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post #3 of 9 Old 02-11-2007, 07:25 AM - Thread Starter
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Quote:
Originally Posted by RobZ View Post

I don't think the velvet will allow for enough absorption of high frequencies.


That's a response I expected which leads to this question which has me perplexed..and ultimately might contradict my opening statement that I understand what I am talking about

If the velvet won't absorb the highs but acoustic panels can be wrapped in acoustically transparent material, then the non-acoustically transparent material (velvet in this example) must be doing something? Otherwise, there wouldn't be an SOP for wrapping panels (or whatever) in something like GOM. No?
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post #4 of 9 Old 02-11-2007, 08:00 AM
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It may reflect highs as well as allowing some to pass thru.
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post #5 of 9 Old 02-11-2007, 08:05 AM - Thread Starter
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Quote:
Originally Posted by RobZ View Post

It may reflect highs as well as allowing some to pass thru.

If I understand correctly, the undesirable behavior of this velvet would be the reflection of highs. So...if I wrapped acoustic panels with it, instead of GOM by example, I could still suffer from those reflected highs?
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post #6 of 9 Old 02-11-2007, 08:19 AM
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It would likely not be as effective as GOM, cotton, etc.
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post #7 of 9 Old 02-11-2007, 08:32 AM
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Quote:
Originally Posted by 500hp View Post

That's a response I expected which leads to this question which has me perplexed..and ultimately might contradict my opening statement that I understand what I am talking about

If the velvet won't absorb the highs but acoustic panels can be wrapped in acoustically transparent material, then the non-acoustically transparent material (velvet in this example) must be doing something? Otherwise, there wouldn't be an SOP for wrapping panels (or whatever) in something like GOM. No?

There are exactly three possibilities for sound energy interacting with a particular object: reflection, absorption, and transmission. Note that diffusion can be considered simply a special case of reflection and/or transmission.

The standard "reverberation room" method for measuring absorption coefficients gives you sound absorption only. It cannot distinguish between sound which is reflected from the material and sound which passes right through it. This sound is 1 minus the absorption coefficient. That is, if the absorption coefficient (energy which is absorbed) over a particular frequency range is 0.35, then 0.65 of the sound energy is being reflected, transmitted, or some combination of the two.

Here are absorption coefficients for 18 ounce (the really heavy stuff!) velour, hung flat with no folds or draping, measured at octave bands from 125 Hz to 4 kHz. Source is the book "Acoustics" by Leo Beranek, McGraw-Hill. 1954.

0.05 0.12 0.35 0.48 0.38 0.36

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post #8 of 9 Old 02-11-2007, 08:43 AM - Thread Starter
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Quote:
Originally Posted by Terry Montlick View Post

There are exactly three possibilities for sound energy interacting with a particular object: reflection, absorption, and transmission. Note that diffusion can be considered simply a special case of reflection and/or transmission.

The standard "reverberation room" method for measuring absorption coefficients gives you sound absorption only. It cannot distinguish between sound which is reflected from the material and sound which passes right through it. This sound is 1 minus the absorption coefficient. That is, if the absorption coefficient (energy which is absorbed) over a particular frequency range is 0.35, then 0.65 of the sound energy is being reflected, transmitted, or some combination of the two.

Here are absorption coefficients for 18 ounce (the really heavy stuff!) velour, hung flat with no folds or draping, measured at octave bands from 125 Hz to 4 kHz. Source is the book "Acoustics" by Leo Beranek, McGraw-Hill. 1954.

0.05 0.12 0.35 0.48 0.38 0.36

- Terry



Thanks Terry....that is exactly what I needed.
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post #9 of 9 Old 10-28-2013, 10:43 AM
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Hi there!

I would love to know if you decided to use the velour, and if so what the outcome was?

Thanks!

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