Vocal Booth Feedback

Hello everyone, I am in the process of building my first vocal booth and would very much appreciate your feedback. It is being built to use for voiceover work. I have had limited control over the process but have learned a great deal from reading the posts here- thank you. The booth is in the corner of a top floor apartment; there is significant outside noise. The frame is built with Quiet Rock. It measures 35"deep, 47.5" wide, 83"high. The size runs the risk of a boxy sound but, due to many reasons, those had to be the dimensions. It does not have a floating floor. My plan is to cover the interior with 4 Inch Owens Corning 703 Rigid Fiberglass Board; possibly cover the floor with 2 inch board. In the corners the plan is to make a couple of super-chunk bass traps, for one of the corners on each end. Using Owens Corning 703 Rigid Fiberglass Board 2 Inch, cutting a 2'x4' sheet of insulation in half, then cutting each square from corner to corner so there are 4 triangles. Then they would be stacked into the corners. There wouldn't be much space for me or equipment though! I would greatly appreciate any feedback and will post pictures soon. Please let me know if you need any additional information. Thank you!

Scrap your ideas, tell us what you are trying to do...you are throwing too much money at a bad situation...

The goal is to create a booth that is as quiet as possible and usable for voiceover work. The booth is already built but has not yet been treated.

Hi there " dtalbott", and Welcome! :)

The goal is to create a booth that is as quiet as possible and usable for voiceover work. The booth is already built but has not yet been treated.

If it is already built, then it is already as quite as it is going to get. Treatment will not make it any quieter; it will just make the interior acoustics better. Isolation (sometimes also called "soundproofing") and treatment are two totally different, and somewhat opposite aspects if acoustics. Isolation deals with keeping sound in or out, and is accomplished with hard, rigid, solid, massive, heavy, stiff materials. Treatment deals with modifying the way sound bounces around inside the room, and is accomplished mostly with soft, light, fluffy, fibrous materials. The materials you use for treatment do not stop sound, and the materials used for isolation do not treat sound. They are pretty much mutually exclusive, diametric opposites. It's a common misconception, but simply false that foam, insulation, and "egg crates" stop sound getting into or out of a room: they absolutely do not and cannot, any more than a kitchen sponge can stop water pouring out the tap, if you hold the sponge right across it. Just like a sponge is good at mopping up water that spilled where you don't want it, so too acoustic treatment is good at "mopping up" sound that spilled where you don't want it. But it can't stop sound, just like a sponge can't stop water. So if your booth is finished, completely built, then the way it is now is as quiet as it is going to get, no matter how much you treat it. If you want it to be quieter, then you need to isolate it more, not treat it. It would be good if you could get some objective readings on how much it is isolating right now, in terms of decibels, using a sound level meter: that will tell us, with real world numbers, how many decibels of isolation you are getting right now, and we can also walk you through the procedure for figuring out how many more decibels of isolation you need. Based on that number, we can then show you different ways of adding additional isolation to your booth that will get you to the number you need. Isolation is not guesswork; it is following a series of steps, and using tried and tested techniques and materials that are know to accomplish the task. It would also help to have photos of the booth as it stands now, especially in how it was built, how the walls an ceiling are sealed, the seals on the door, the ventilation system, the penetrations for the electrical and signal cables, etc. Those are all potential sources of lost isolation, so if you can post photos of those we can see if there is anything more you can do there to increase your isolation, without needing to go to extremes of additional layers. We'll also need specif details of how it was built: what materials were used, how thick, hoe they were attached, how they were sealed. etc. In other words, everything there is to know about it. The good news is that there probably are solutions available to you, but we need to understand what you have before we can tell you how to fix it. - Stuart -

Thank you! The purpose of the OC 703 was for treatment, as you say. It had been recommended over foam. The (dream) goal is to have the space as dead as possible. The booth is located near windows; that isn’t ideal but there was no other option. Right now the sound booth measures 35"deep 47.5" wide 83"high In side it is 58’’ in diameter It’s built with 2 layers of Quietrock. There are 2.5 inches of soundproof sound insulation between the layers. There are also vents, going up into the ceiling and zig-zagging 25 ft across to the other end of the room. As this is a small booth, the treatment plan was to cover the interior with 4 Inch Owens Corning 703 Rigid Fiberglass Board; the floor would be covered with 2 inch board. However, this would take off four inches on the inside of what is already a small booth. Would it be better to cover the interior with 2 inch OC 703 instead of 4 inch? In the corners the plan is to make a couple of super-chunk bass traps, for one of the corners on each end. Thank you very much for your help!

Much better! All those details and the photos help a lot to understand what you have.

It’s built with 2 layers of Quietrock. There are 2.5 inches of soundproof sound insulation between the layers.

OK, but is there any decoupling in there? In other words, did you use resilient channel or isolation clips to keep the drywall on one side from touching the studs? From the photos, is appears that there is no decoupling. Also, how thick is the drywall: I'm guessing 1/2"? And since you have 2.5" of insulation, that implies that the framing is 2x3: Is that correct? If so, that shoule be getting you roughly 30 dB of isolation, except in the low frequencies, where it will not be very good at all. That's roughly the same as you would get from a normal house wall. So the big question here is: are you getting enough isolation? Is it quiet enough in there to record? If you are happy with the amount of isolation, then it is time to do the treatment, but if you don't think that there is sufficient isolation, now is the time to fix that, BEFORE you start treating. That's why I'm harping so much on this point: After you do the treatment, it is really hard to isolate more. So if you need more, do that first.

As this is a small booth, the treatment plan was to cover the interior with 4 Inch Owens Corning 703 Rigid Fiberglass Board; the floor would be covered with 2 inch board. However, this would take off four inches on the inside of what is already a small booth. Would it be better to cover the interior with 2 inch OC 703 instead of 4 inch?

It is a very small booth (more of a closet, really) so the only real option is to kill it. Meaning thick absorption all over: But as you say, taking 4" off each side is going to leave you squashed up like a sardine in a can, inside there! I would suggest doing two adjacent walls with 4" (any two: it doesn't matter), plus the ceiling, then try out with 2" on the third wall, and nothing on the door-wall. See how that sounds: if it is still not good, then add 2" to the door-wall. And if that still doesn't fix it, then add another 2" to the third wall, plus 2" to the ceiling. In other words, do it in stages, and only add as much as you need to get the sound where you want it.

In the corners the plan is to make a couple of super-chunk bass traps, for one of the corners on each end.

It's a vocal booth: you don't need bass traps. And you don't have room for them anyway! - Stuart -

Dear Stuart, You are AWESOME. Thank you very much for your response. I believe you are correct on all counts. Can you suggest a way to improve the isolation…without dismantling what is already in place? I would be open to that but doubt it will be possible for various reasons. I really appreciate your advice!

Can you suggest a way to improve the isolation…without dismantling what is already in place?

Well, you don't need to dismantle all of it, but you at least need to get the drywall off the inside of the booth, install resilient channel, then put it back again. And since you'll doubtless damage that drywall trying to get it off, you won't be able to put the same stuff back... but you CAN re-use it! You don't need to throw it away. Take it off as carefully as you can, cut it into strips that fit between the studs, inside the wall, and press it up against the drywall on the outside. Hold it in place with cleats, then seal around the edges with acoustic sealant, or even ordinary bathroom caulk (the type that stays soft and rubbery forever, even when it has cured). Then put good insulation in the cavity, before you put the new drywall on. The new stuff should be 5/8" (15mm), not the typical thin stuff.

There are 2.5 inches of soundproof sound insulation between the layers.

Well, if it is insulation, then it isn't soundproof! 8) :!: What type of insulation is in there? If it is the right type, then you can re-use it. Take it out carefully, put the old drywall in between the studs, then put the insulation back, and put the resilient channel on. Doing this should roughly double the amount of isolation you are getting right now, so subjectively it should be about half as loud. If you work carefully, it could even be triple (one third as loud). That's pretty good for a few hours work! :) - Stuart -