Heavy curtains as acoustic room treatment?

[kemmler3D]

Before I get my measurement mic and find any specific problems to solve, it's just a simple question - do curtains do anything? So far the answer is yes, maybe, it depends

They definitely do something, whether they do the thing you need them to do depends on the situation. But covering 1 wall is unlikely to make anything worse, likely to make things better. Covering all 4 walls could be too much.

 

[Timcognito]

Before I get my measurement mic and find any specific problems to solve, it's just a simple question - do curtains do anything? So far the answer is yes, maybe, it depends

Amir said yes a few posts up.

 

[akamatsu]

I use heavy curtains (black out curtains from Ikea) to tame the RT60. They pretty much are able to cover most of the right side wall. Right now I'm listening with all curtains open so that the amount of window/wall covered is minimal. They still seem to be doing a good job along with other furnishings. If you clap your hands in the room and hear a secondary echo, the RT60 needs taming. You want to hear some decay. As others have said, you don't want to over damp. I've heard music in a room where the acoustic room treatment salesperson went overboard. It was dead.

 

[Justdafactsmaam]

Before I get my measurement mic and find any specific problems to solve, it's just a simple question - do curtains do anything? So far the answer is yes, maybe, it depends

They definitely do something. The question will be do they do what you want them to do

 

[Newman]

it's just a simple question - do curtains do anything?

Short answer: yes, heavy drapes definitely do something, and in a bare room it is a positive thing.

Imagine a bare room with nothing but a hifi and a kitchen chair for listening. It will be too reverberant, and the following normal-furnishing treatments will all be positive for the sound quality:-
- wall-to-wall carpet with premium underlay
- heavy drapes over the windows and sliding glass doors
- a big boofy couch or two with soft upholstery

cheers

 

[Holmz]

Before I get my measurement mic and find any specific problems to solve, it's just a simple question - do curtains do anything?

Yeah they do, but maybe too much for higher freqs.

So far the answer is yes, maybe, it depends

And, as I mentioned earlier, you probably want to first concentrate on lower freqs.

 

[dlaloum]

Before I get my measurement mic and find any specific problems to solve, it's just a simple question - do curtains do anything? So far the answer is yes, maybe, it depends

Well first you need to define the type of curtain, weight, material and surface finish... - all of those will impact, albeit at different frequencies.

So can a curtain have an impact - yes it can.
Will a specific curtain have a specific impact - depends (much analysis needed)

Heavy curtains, with substantial pleating can impact down to 100Hz...
Surface finish of the curtain may impact on the high frequency reflectivity, pleating will disperse rather than reflect HF...
Textured/velvet finishes will absorb more HF than smoother shinier finishes

IMO and experience - large glass surfaces are the devils tool !! Curtains resolve many of the issues caused by Glass.

Glass with curtains makes it more "wall" like - thank god for the curtains in our large open living space! If I am listening/watching something, I try to make sure the curtains are closed.

Other unobtrusive wall treatments include .... bookshelves !! (and books too!)

 

[dlaloum]

They definitely do something, whether they do the thing you need them to do depends on the situation. But covering 1 wall is unlikely to make anything worse, likely to make things better. Covering all 4 walls could be too much.

Covering all 4 walls, you would be heading for a quasi-anechoic setup.... and nobody likes listening to gear in an anechoic space!

 

[dlaloum]

As an aside, some of the best auditoriums in the world, have adjustable curtains/wall hanging drape devices, which are used to adjust the acoustics to suit what is desired for the performance.... so the answer to "do curtains affect acoustics" is a definitive YES....

The question after that is whether your objective can be achieved with curtains, and defining the objective and the curtains to meet it.

 

[kemmler3D]

Covering all 4 walls, you would be heading for a quasi-anechoic setup.... and nobody likes listening to gear in an anechoic space!

Quasi-anechoic but probably only down to 150-200hz at best, so more like a boom boom room than anything.

 

[decryption]

They definitely do something, whether they do the thing you need them to do depends on the situation. But covering 1 wall is unlikely to make anything worse, likely to make things better. Covering all 4 walls could be too much

At best I'd be looking at putting curtains on the left and right walls, probably wouldn't on the back wall and there's not much space on the front wall due to the 140" projector screen.

So can a curtain have an impact - yes it can.
Will a specific curtain have a specific impact - depends (much analysis needed)

Heavy curtains, with substantial pleating can impact down to 100Hz...
Surface finish of the curtain may impact on the high frequency reflectivity, pleating will disperse rather than reflect HF...
Textured/velvet finishes will absorb more HF than smoother shinier finishes

IMO and experience - large glass surfaces are the devils tool !! Curtains resolve many of the issues caused by Glass.

Glass with curtains makes it more "wall" like - thank god for the curtains in our large open living space! If I am listening/watching something, I try to make sure the curtains are closed.

Other unobtrusive wall treatments include .... bookshelves !! (and books too!)

Thanks for the tips. Would certainly be using a velvet/textured finish, kinda like a woolen blanket, not a shiny polyester finish curtain.

 

[Holmz]

…
Thanks for the tips. Would certainly be using a velvet/textured finish, kinda like a woolen blanket, not a shiny polyester finish curtain.

I read @dlaloum as suggesting that you might want a heavy curtain, but with more of shiny finish to not totally such out the high freqs.
Maybe we should get him to elaborate?

 

[dlaloum]

I read @dlaloum as suggesting that you might want a heavy curtain, but with more of shiny finish to not totally such out the high freqs.
Maybe we should get him to elaborate?

I would go for a velvet or other textured finish, so that you reduce direct reflections in the high frequencies.

You don't want too much of it... but traditional listening room setups have had live end/dead end ie: one side absorbs and/or disperses high frequencies, the other reflects them more - providing a more spacious sound... the soudstage...

You do want some reflected sound to reach your ears for a more natural effect with stereo, but you want that reflected sound to be sufficiently delayed for your automatic hearing reflexes to "discount it" as part of the direct sound -that way it doesn't affect imaging, but it still provides some reflected sound so you get more of the ambient soundstage.

Typically that means looking to absorb/disperse high frequencies on surfaces that are close to the speakers (as a direct reflection from there would confuse the image, as it is too close in time to the direct sound from the speakers), and you would look to allow more reflection from more distant surfaces.

In a pure surround sound world.... you would be in an anechoic room, and all this would be handled by the system itself via direct sound exclusively.... but in a more pragmatically real, hybrid world in which we live.... multi channel setups have the same requirements as stereo.... and 80%+ of the listening experience comes from the front L&R or L/C/R .... so you typically want absorbent stuff near the speakers and less absorbent stuff at the rear of the room. (all of this talking about mid to high frequencies... NOT BASS)

 

[Guermantes]

We recently looked at installing an acoustic curtain in a room at work, but the cost-performance was not great. So we installed this Primacoustic kit after determining where the specular reflections were for the listening position:

Primacoustic London 12 Room Kit

Vastly improve the acoustic sound of your room by installing the Primacoustic London 12 room Kit - it looks great and it's more effective than acoustic foam.

www.soundseasy.com.au

The result was quite good, especially at reducing slap echo in mid to high frequencies. After running measurements with REW, we discovered that the remaining reflective issues (other than modal resonances) were the table and computer monitor at the listening position.

With curtains, space between them and the wall they are covering will improve lower mid-frequency absorption:

Effects of folding (7/8 is the least amount of folding):

 

[nathan]

Not bad but notice how much more broadband and consistent an actual panel is, and far more effective down to and through the transition frequency of most rooms.

 

[Bjorn]

Please note that a reverberation measurement is not applicable to a small room. Meaning the effect we see in the graph will not be as good when the panel is placed in living room. It will not absorb as low. The total dimension also matters here. One single panel doesn't yield this result.

 

[nathan]

The graphs simply show the relative effectiveness of the materials, not the end result.

The end result is based on how many panels are used in a room. And it can be measured. CEDIA/CTA’s RP22 summarizes this nicely:

Right down to the targets:

 

[nathan]

And the Dolby standard for a mixing room for ATMOS music has a very similar RT60 / RDT as well (it is buried in their EXCEL tool for designing mastering suites):

Suffice to say, in both instances (CEDIA/CTA and Dolby) the goal is event consistent decay across the audible frequency range, with some rise in the bass.

The curtains will not give this even consistent impact (see their graph which looks like a mountain peak) whereas a conventional fiberglass, rock wool, or similar acoustic panel does a better job.

 

[Newman]

The curtains will not give this even consistent impact (see their graph which looks like a mountain peak) whereas a conventional fiberglass, rock wool, or similar acoustic panel does a better job.

Agree with what you are saying, but bear in mind Toole’s analysis and conclusion that, for a domestic listening situation, well-implemented domestic furnishings can give a very satisfying listening space. We don’t want to lose sight of that, along with the fact that RT60 is not considered to be a suitable measure of domestic sized rooms, where the diffuse state is not achievable.

Having said that, I confess to personally using 100mm polymer wool batts in my own room.

 

[nathan]

Agree with what you are saying, but bear in mind Toole’s analysis and conclusion that, for a domestic listening situation, well-implemented domestic furnishings can give a very satisfying listening space. We don’t want to lose sight of that, along with the fact that RT60 is not considered to be a suitable measure of domestic sized rooms, where the diffuse state is not achievable.

Having said that, I confess to personally using 100mm polymer wool batts in my own room.

Agreed. Toole's data stemmed from two channel listening tests with EXCELLENT speakers (ie, flat response and extremely consistent off axis dispersion) in a conventionally furnished domestic space. The OP is doing multichannel sound in a small room with nothing on the walls.

I know technically RT60 isn't a thing in a domestic sized room, but RDT is.....and I've given the industry standards for both mastering suites and for home theaters in the prior posts. One doesn't have to follow them, but it is worth knowing about them, since the OP was asking about curtains, and all the data suggests there are better ways to treat a dedicated theater room with bare walls.

And, frankly, while I have a well treated home theater (in a spare bedroom, so its small) with a linear RDT achieved via rock wool panels, I completely agree that in a Great Room, a pair of excellent speakers can sing without any dedicate treatment......and that's what my Great Room does. A pair of 126BE with no treatment around the listening area. And it is magic.