John Sayers' Recording Studio Design Forum Archive

New York, USA
Please feel free to erase this ? if it is a waste of your time.

I am simply trying to get some not-so-technical advice on how to improve the acoustics in a "music room" in our newly constructed house, in the basement. My husband uses this room mostly for acoustical guitar and mandolin playing, but eventually we are going to move the upright piano down there. He also has a Fender Strat which will probably get used down there as well. Probably will not be used for recording at this stage, but possibly in the future. Rural location, no neighbors to be concerned about.

I would like to know if you think adding cork to the walls, and possibly ceiling would improve the acoustics in this room. I have read as much of the tech stuff as best I can, but it is simply too much information for me to comprehend. This might be kooky, but I have thousands of wine corks, and thought that either gluing or tacking them to the walls and/or ceiling might take away from the horrible basement acoustics we currently have down there. Me being the artist (NOT the musician) I think it would look really cool too! I don't have enough to do the whole space, but would one wall or even 2 be an improvement or a waste of time? Later we will look into some serious acoustic upgrades, but for now, would this help at all?

The basement space is approx 22' long x 15' wide. One of the long walls has an opening 4'-wide, open to the rest of the basement and the stairs going up come off of this opening if you turn right. The walls are ARXX constructed (insulated concrete forms)...basically an inch or so of styrofoam with concrete poured in the center. There is 1/2" drywall covering the foam on the inside. There is one small (12" high x 28" wide) window just below ceiling level, on a long wall at the opposite corner of the "doorway". Ceiling is drywall, 8'-high, floor is unpainted concrete.

I apologize (again) for my stupid question, but all I can find online are the really serious acoustic wizards like yourselves, or talk about cork flooring and its sound-deadening qualities...nothing in between.

THANK YOU!

Hi, and welcome.

There is an announcement at the top of the forum about what to do to assure getting as many responses as possible.
The announcement leads to this post (click here). Please could you take another look at that, 'cause there's something missing!

I apologize (again) for my stupid question,

I don't think it is a stupid question at all! Cork does have some acoustical uses, and you do have a problematic room, so it isn't silly to think that maybe "A" will help "B".

Let me try to give you some answers, without getting too technical.

First, something totally unrelated to cork: your rooms dimensions. There are good relationships between the dimensions of a room (height, length, width), and there are bad relationships. This is normally referred to as the "room ratio". In your case it isn't bad, but it isn't fantastic either: However, I wouldn't worry about it too much, since you don't seem to be looking to make a professional studio out of it, just a place where your hubby can play his instruments and it will sound good. Your ratio is probably good enough for that. But if you do want to put a studio in there at some later stage, then you should probably think about improving that.

Next, you don't really say what it is about the acoustics that you want to improve, and it would help if you could be more specific. There are two major and totally incompatible aspects to acoustics. One is "isolation" (often incorrectly called "soundproofing"), and the other is "treatment".

So if your problem is that you (or your neighbors) cannot stand the noise coming up out of the basement when he is playing, or he cannot stand the noise coming down from the rest of the house, then you have an isolation problem, and there are several ways of dealing with that. Cork will not help with that issue.

But if everything is fine on that front, and everyone is happy with everyone else's noise, then you most likely have a treatment problem. In other words, when your husband plays in that room, it just doesn't sound good: the instruments don't sound "right", or there are unpleasant echoes, resonance, twangs, and that kind of thing. This is a very different issue, and from the way you described the construction of your room, I'm guessing that this is what you are experiencing. If this is the case, then cork might be part of the solution, but it wont be all of it.

The problem is that all small rooms (like yours) have problems with low frequency sounds, and in order to fix those problems you need really LARGE things to treat them. What we normally recommend as a good, simple and cheap solution for getting started with treatment, is simply stacking ordinary home insulation (fiberglass or mineral wool) in a few corners of the room, floor to ceiling, and at least two feet deep. Of course, stacks of insulation in the corners is pretty ugly to look at, but you can make a simple wooden frame in front of it, diagonally across the corner, and put some kind of cloth over the frame.

This kind of device is called a "superchunk" bass trap, and is very effective. That alone has an amazing effect on the acoustics of a room. But it isn't everything.

Most likely you also have sound bouncing around between the walls in various manners, setting up things "standing waves" and also causing flutter echo, and other unpleasant effects. There's an easy way of dealing with this too, and here your corks might be useful. Normally we recommend a couple of different approaches here, and the simplest one is getting panels of Owens Corning 703 semi-rigid insulation (abbreviated "703"), which is cheap and has great acoustic properties. You can just place a few panels of that against your walls (it normally comes in 4' x 8' panels, 4" thick), and once again it isn't pretty so most people make frames for it and cover it with cloth. You DON'T need to cover all your walls with that! If you did, you would over-treat your room, going too far in the opposite direction and making it unpleasant for different reasons. That would be an acoustically "dead" room. So the best plan is to "checkerboard" your 703 panels along the walls, so that each panel faces a piece of bare wall on the other side of the room.

The final touch is the ceiling: if this is an average basement, then you have open joists up above you. Once again, you can place panels of 703 up there, between the joists.

The floor? Leave it like it is: bare concrete on the floor is actually very good acoustically. Or if you don't like the looks, then lay some laminate flooring directly on top of it. Do NOT use carpet!

OK, so what about your cork? Well there is another type of treatment that you might want to try, called "diffusion", which basically means breaking up sound waves by putting large objects in their path. I'm thinking that you could build some diffusion panels to use on one of the walls, instead of the 703, and glue your corks to some type of random wooden shapes that stick out from the wall at various depths. I reckon it would probably give a very nice effect visually, as well as being useful, acoustically. It would not be any kind of standard acoustic treatment, and the effects are a little bit unpredictable, from the theoretical point of view, but it certainly won't do any harm, and personally I think it would be pretty neat!

I would suggest basing your "wood block and cork" diffuser on one of the normal diffuser principles, which could be ploy-cylindrical maybe, or QRD, or even a combination. Or it could just be random patterns of, for example 6" by 6" wood blocks with corks glued to them, arranged in a checkerboard pattern on a 4' by 8' backing, at depths that vary from, say, 1" away from the wall to 8" away from the wall (you do need to make the squares fairly large to have a good acoustic effect).

DISCLAIMER! OK, now before someone climbs all over me for suggesting a totally untried and non-theoretical treatment on a forum that is know for being soundly based in science, I will say that I have no theoretical basis at all for what such an arrangement will do to a room! Not a clue! Guilty as charged! However, I do know that even randomly arranged wells of various depths will have some useful diffusive effect, and I do know that using a large scale QRD with smaller scale QRD's inside it is also effective, so I do have a hunch that this "cork diffuser" would have a positive effect on the room, and in the very worst case it most certainly will do no harm, so I say: why not? It's worth a try! If I had a thousand wine corks lying around, I might even be tempted to try it myself! (Hmmmm... there's a thought! This gives me a great excuse to start drinking more wine.... all in the interests of acoustic science, of course! )

But seriously, if you want to give it a try, I would do the "superchunks in the corners" treatment first, followed by at least some panels of 703 on the walls and ceiling, then play around with various designs for your diffuser, and I'm willing to bet it will be a success!


- Stuart -

John Sayers said, on some thread around here, that cork was the Owens corning 703 back in the day. Or something close to that. Based on that I built my cloud using hard backed 5/16" cork.

I was really impressed with how it worked, the cloud that is.

>>>So if your problem is that you (or your neighbors) cannot stand the noise coming up out of the basement when he is playing, or he cannot stand the noise coming down from the rest of the house, then you have an isolation problem, and there are several ways of dealing with that. Cork will not help with that issue.<<<

This is not the problem.

>>>when your husband plays in that room, it just doesn't sound good: the instruments don't sound "right", or there are unpleasant echoes, resonance, twangs, and that kind of thing. This is a very different issue, and from the way you described the construction of your room, I'm guessing that this is what you are experiencing. If this is the case, then cork might be part of the solution, but it wont be all of it.<<<

This is the problem.

I will try what you have suggested and I will keep you posted as to my progress. I don't need scientific guarantees, just some hope that what I am doing will help somehow.Thank you so much for your helpful answers!

adding room treatments will shape the space to get rid of the echoes and odd frequency responses, some other work might be needed if you have some resonances due to loose boards etc. what those treatments are exactly will be determined by a variety of factors, budget being one of them.

I think that this information is the best.

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