Putting Auralex in a corner does not a vocalbooth make...

Greetings, everyone! In an attempt to tame the wild echoes in my studio, I purchased some Auralex foam. My plan was to place some in a corner of my studio so that voice-over talent could speak into a microphone situated in of the corner. I just did a quick and dirty setup to test the foam I was under the impression that the foam would absorb most of the frequencies from a human voice, and thus prevent the sound from reflecting off of the wall behind the foam and into the rest of the room. To my dissapointment, I found that the foam only absorbed some of the highs and allowed the rest of the sound to bash about the room as it has always done. Have I wasted $120 of my hard-earned money, or is there something else that I can do with the foam that will give me the desired effect? Thanks, Jack

Aloha Jack, So sorry to hear that it didn't work out. Before going further, any chance you could edit your profile to include your location. It would help to know where you are as it sometimes determines the advice given due to availability, terminology and cost of materials. It's also part of the forum guidelines. Thanks. :) Is it possible to move the voice-over position away from the walls? You'll still have to address the wall reflections, but perhaps with another type of absorber design. Have you considered any of these? http://www.johnlsayers.com/HR/index1.htm Also, I've recently had a couple of responses about vocal booths on my thread: http://www.johnlsayers.com/phpBB2/viewt ... c&start=30 (scroll down to about 3 posts up from the bottom, and over to the top of page four) Another post: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4824 Hope these help. Aloha 8)

Thanks for the quick response, kendale! John's wall units would of be the best solution of all, of course, but that is beyond my means at the moment. Your idea to put OC 703 / rockwool in a vocalbooth is definitely a good idea. I would imagine I could just put some of that in a corner like I did with the Auralex (it would likely need a frame and some cloth covering though), and it would work marvelously, correct? I just wish there were a way I could use the auralex, since I already have it. :)

After doing some more experimentation with my recently purchased foam, I have come to wonder why Auralex calls it "acoustic" foam. There is nothing acoustical about it; they don't really absorb sound at all. Although the foam makes a comfortable head rest, the stuff is absolutely worthless for just about everything else. I really feel sorry for people waste loads of cash lining their studios with this stuff with the false impression that it will make a difference. This really burns my biscuits! I feel the urge to go into a massive tirade right now, spewing profanity.....but I will resist that urge. All I can say is DON'T BUY AURALEX FOAM! The wise elders of this forum warned against it, but I still had to learn the hard way... :evil: Anyhow, "Logically" speaking, lining the corner of a room with some highly absorptive material should make a good vocalbooth, right? Would Mineral Fiber like this do the trick?

Judging by the photo it looks like you situated the voice talent so that they were speaking towards the corner. Are you using a cardioid microphone? If so you would get better results if you had the talent speak away from the corner. In your current arrangement, you get all the reflections of the room because the mic is facing the live walls. If you turn things around by putting your talent in the corner the room will be in the null of the cardioid pattern and the foam will be positioned so that it knocks down reflections reaching the front of the mic. This won't eliminate all of the reflections reaching the mic but it will likely improve things. Ultimately I think you will probably be happier come up with a more comprehensive treatment plan but it's worth a try before the Auralex becomes a $120 pillow.

jackmeaph wrote:

After doing some more experimentation with my recently purchased foam, I have come to wonder why Auralex calls it "acoustic" foam. There is nothing acoustical about it; they don't really absorb sound at all. Although the foam makes a comfortable head rest, the stuff is absolutely worthless for just about everything else. I really feel sorry for people waste loads of cash lining their studios with this stuff with the false impression that it will make a difference. This really burns my biscuits! I feel the urge to go into a massive tirade right now, spewing profanity.....but I will resist that urge. All I can say is DON'T BUY AURALEX FOAM! The wise elders of this forum warned against it, but I still had to learn the hard way... :evil: Anyhow, "Logically" speaking, lining the corner of a room with some highly absorptive material should make a good vocalbooth, right? Would Mineral Fiber like this do the trick?

:evil: While I have no shares in Auralex or any other foam or whatever other material company, this post is about you not Auralex. If you buy 1" of glassfiber, then start experimenting with them, you could as well say "Don't buy from Owens Corning" or whatever other producer. If one buys a new General Motors car, normally one doesn't say: Don't buy Opel because it sunk when I tried to sail with it to the UK. Auralex, as lots of others do as well, sells different materials with specifications (lots including measurements) targetted to specific purposes. It's of course easier to blame others called "them". "They" did it wrong ....... I'm also not a traditional foam user, but that's different than blaming a supplier for delivering exactly what you ordered. You can blame them if they misinformed you on an exact question or problem solution. And if they did I'm your biggest supporter in function of this misinformation, Auralex or not. While the fiberglass boards solutions are indeed perfect, Auralex could deliver as well foam material doing the job. And that foam is more expensive than a DIY solution is something one can know beforehand as well. But that's as well valid for any other commercial finished product.

A couple of acousitc factors are involved here, along with studio technique. Thin absorbent materials are noteffective at low frequencies. The human body is an omnidirectional source at low frequencies. Regarding studio technique: if you are using a directional microphone as in the picture, then the effects of any absorbent will be minimal because the area of reduced sensitivity is aimed at the direction of lowest signal! Before geting too much more disappointed try the setup as you showed in the picture witht he vocal talent where the microphone is and place the microphone where the talent was. Good Luck! Andre

I think I just realized what my mistake was. I purchased Auralex 422 Foam, not StudioFoam. From what I can gather, the 422 foam is designed only for decorating a room. It is described as follows:

They make great borders to finsih off almost all Auralex products

I had initially looked at the specs for Auralex's StudioFoam Pyramids, and they actually have a decent set of absorption coefficients, although a little bare in the low-end. I just now looked at the specs for the 422 foam, and I can definitely see why it is performing like it is. Here are some of the specs: NRC- .60 Absorption Coefficients: .85 @ 2.5 kHz .71 @ 1kHz .54 @ .5 kHz The 2" StudioFoam pretty much stays above 1.0 until around 500 Hz, so there really is a dramatic difference between the two products. My mistake was to assume that all 2" Auralex foam has the same specs. No wonder I was so dissapointed! That's why I became so angry, because I couldn't understand why something that supposedly has absorbtion coefficients close to 1 throughout most of the frequency spectrum would perform so poorly. I thought I had been jipped, but it turns out that I just wasn't paying attention to what I was buying. How embarrassing! :oops:

Sorry to be posting so much...

AVare wrote:

A couple of acousitc factors are involved here, along with studio technique. Thin absorbent materials are noteffective at low frequencies. The human body is an omnidirectional source at low frequencies. Regarding studio technique: if you are using a directional microphone as in the picture, then the effects of any absorbent will be minimal because the area of reduced sensitivity is aimed at the direction of lowest signal! Before geting too much more disappointed try the setup as you showed in the picture witht he vocal talent where the microphone is and place the microphone where the talent was. Good Luck! Andre

Andre and blunderfonics, you both make a good point. I just tried swapping places with the vocalist and the mic, though, and the sound is till way too live. It is definitely better than having the vocalist facing the corner, though, because that creates some atrocious flutter echoes! The room I am in is about 22 X 15 and it has very little absorptive material in it, save for some thin rugs and a futon in the back, so I guess I am facing an uphill battle. Questions 1. Would either of the two arrangements of the vocalist and the mic produce an acceptable result if I had better absorption material in the corner? I am looking for a very dry sound, and so I would like to get rid of all reflections if I can. 2. If the answer to question #1 is yes, would 2" Auralex Mineral Wool work?How about 2" studiofoam wedges? Here are the specs for quick reference 3. Is there any other solution under $200 that would allow me to record dry vocals? Thanks so much for the responses, guys!

First, treating a small corner of a room won't get you "dry" vocals, you either need a dry ROOM or a (smaller) dry room. Least expensive (non-soundproof) way to do that is a couple of pieces of plywood or OSB, some 2x4,s nails, and a door - Build a booth in a corner. If you have enough of the Auralex trim, you might consider making 3-4 LAYERS of it and leave a 2-3" air gap between that and the wall - that will improve its performance a LOT. otherwise, check locally for mineral wool ($200 won't buy enough from ANY acoustic manufacturer, you'll need to DIY the panels with your own cloth covers, etc) - spacing the panels off the walls by a few inches will help this material also (more even absorption, less boxiness) http://www.spi-co.com/servicecenterdirectory.cfm They have 4 locations in Ohio, CALL before you drive. Each store is different, and seem to have different products at different times. What you're looking for is either rigid fiberglass or mineral wool or rockwool, in at least 2" thickness, density around 3 to 4 PCF. Typically comes in 2' x 4' "boards". Expect to pay somewhere around a dollar a square foot for 2" stuff, more or less... Steve Just looked it up, this is the last quote I got from their location in Portland - 4pcf 4" 2x4' thermafibre, raw - $.81/sf.

knightfly wrote:

First, treating a small corner of a room won't get you "dry" vocals, you either need a dry ROOM or a (smaller) dry room. Least expensive (non-soundproof) way to do that is a couple of pieces of plywood or OSB, some 2x4,s nails, and a door - Build a booth in a corner. If you have enough of the Auralex trim, you might consider making 3-4 LAYERS of it and leave a 2-3" air gap between that and the wall - that will improve its performance a LOT. otherwise, check locally for mineral wool ($200 won't buy enough from ANY acoustic manufacturer, you'll need to DIY the panels with your own cloth covers, etc) - spacing the panels off the walls by a few inches will help this material also (more even absorption, less boxiness) http://www.spi-co.com/servicecenterdirectory.cfm They have 4 locations in Ohio, CALL before you drive. Each store is different, and seem to have different products at different times. What you're looking for is either rigid fiberglass or mineral wool or rockwool, in at least 2" thickness, density around 3 to 4 PCF. Typically comes in 2' x 4' "boards". Expect to pay somewhere around a dollar a square foot for 2" stuff, more or less... Steve Just looked it up, this is the last quote I got from their location in Portland - 4pcf 4" 2x4' thermafibre, raw - $.81/sf.

Thanks for the very thorough response, Steve! If I understand correctly, it is a bad idea to have a vocalist speak into a corner, regardless of how much acoustic treatment there is in the corner, because: 1. Being so close to walls makes things sound boxy. 2. Like Andre said, voices are omnidirectional in the lows, so sound will still end up going out into the room. Is this correct? If so, it seems that my only option is an ISO booth. I think I will look into building one, and so I have a couple of questions, if you don't mind: Questions 1. Does the booth need to be built to provide a large degree of isolation (2-leaf, caulking, etc.), or will standard building techniques be sufficient to eliminate reflections? 2. If the answer to #1 is "no", then does it even need a ceiling?

"boxy" is more a result of uneven absorption - denser absorbers (within reason) and deeper distance from surface to wall will help this. Human voice for the most part doesn't have a lot of energy at low enough frequencies to be truly omnidirectional, but yes it will have a noticeable effect - especially on a male vocalist (not Steve Perry or Sting) :wink: If you don't need isolation for its own sake, double walls won't affect acoustics inside a booth by much, especially at vocal frequencies. If your ceiling is absorptive over the top of the booth (not really a booth without a lid) it might actually improve acoustics inside by acting somewhat as a bass trap. For a booth, I'd start with only about a 2 foot wide band of absorption (2" rockwool, spaced at least 2" off the walls) and center it at source/mic height - same with the ceiling, no (or thin) carpet on the floor, and slightly splayed walls (1" in10") if you can. (flutter) If this isn't enough, you can always ADD absorption; light carpet's only contribution would be minimising foot noise during recording, and the "minimalist" wall absorption should help keep the carpet from making the room too dull in the high end... Steve

Jack, Any 2" acoustical foam will absorb well down to around the 200-300 Hz range. You really should consider complementing your Auralex DST-422s with some corner treatments, like LENRDs or ??? The typical male voice can have fundamentals down into the 100 Hz range. In a small space like a vocal booth, the typical application is 2" acoustical foam plus some corner treatments. I think if there is any way you can augment your setup with some thicker treatments in the corner(s), you will be much happier with the results.

Putting the vocalist is the corner is actually a rather nice solution, but Andre is right. You have them facing the wrong direction. Using a cardioid or super-cardioid mic and appropriate absorption behind the vocalist, you can get pretty decent isolation. I don't think your Auralex purchase was in vain. If I was you, I would mount rockwool or something similar slightly off the wall as Steve suggested, then cover it with your Auralex - ceiling included. It will look nice and you'll have good absorption in the vocal range. Then aim that cardiod mic INTO THE CORNER. It also has the added benefit of a happier vocalist who isn't starring into a dead corner. ;) Thomas

IMO, a major drawback of placing a sound source in a room corner is that you have effectively increased the directivity of the source by a factor of 8 (or greater than 9 dB). For example, if you place a source in the middle of a room (away from reflective walls), the source has a directivity of 2 (assuming high ceilings and a moderately sized room) which equates to roughly a 3 dB increase in sound power. If the Auralex is absorbing the mids and highs (typical of foam), a 9+ dB increase in sound power inherent by placing the talent in the corner should subjectively result in a much more "boomy" sound by comparison. Plus, for the same vocal effort, this significant increase in sound power may serve to increase the audibility of other room anomolies. As knightfly indicated, you should strive for a dry room configuration with no coloration to get dry vocals and a properly designed ISO booth would be perfect for this application.