Is this enough for sound absorption and diffusion?

Dalton Lynne

New member
Hello all - I'm in the process of building a vocal booth that is double-walled, has double layers of sheet rock on each side and the ceiling with green glue in between (and acoustical sealant), and with two angled doorways across from each other (one doorway having two doors). It's roughly 6.5 x 6.5 x 6.5 and was constructed for the purpose of audiobook recording/voiceover work. I've been trying to figure out how to do proper acoustical treatment once it's ready for me to "move in." I used this video to come up with a plan but am not sure if what I'll do is sufficient or not. Here is the video:

YouTube

So, based on that information (based on voice usage) I'm planning to use two 23" x 23" diffusers (one in front of me, one behind), and sound absorption panels (one on each wall beside me, and one or two on the ceiling.

Does that sound adequate, or am I way off base?
 
If you make a sealed room it will need an HVAC system to get fresh air in there so the talent can breathe.

Acoustic treatment depends a lot on what problems you have in the room. "Small" usually means more problems (modes), and "cube shaped" means the room modes generated from each surface will be at the same frequency, so they will stack.

If you go here,

Room Mode Calculator

and type in 6.5 for length, width and height, the mode calculator will tell you the mode frequencies. You want to avoid seeing the same frequencies stack. Bass traps and diffusion can help to tame the problem, but stacked modes will complicate the problem. It might help to build a trapezoid room to scatter the modes, or change the length, width and height so they are not the same.

A 6.5 cube or 275 square feet is a tiny closet that will have a lot of problems.

If you go here,

Room Size & Volume Charts – Acoustic Fields

and scroll down to the "good sound room volumes" chart, it's basically saying bigger is better.
 
Thanks so much for your reply. The room has already been built, so that part can't be changed. Below/attached is a rough sketch of what it looks like (I hope I did that right). I will check out that link you posted (though I think I won't understand how any of that translates with regard to how many diffusers/absorption panels I need). Thanks again!

Vocal booth.jpg
 
If it were me............I would put some kind of floor to ceiling or near as bass traps in the 90 degree corners. But not too large in width. I would then put something in your 90 degree ceiling to wall corners but only smallish otherwise it would get a little claustrophobic.

You do not need too much bass treatment as it's only a vocal booth. Unless you are really Bazza White reincarnated?

Then line the rest with proper acoustic foam walls and ceiling.
 
I wouldn't even put any drywall on the inside. I'd fill the studs with OC703 or 705 and cover it with heavy cotton duck. That space is going to be an acoustical nightmare otherwise. Might still be actually. Relatively insane modes all over the vocal spectrum. And 95% of the energy far below what foam is going to have any effect on.
 
And he is correct about the drywall/plasterboard. If you need or want solid walls then use 18mm osb or similar.
 
You've already built a *soundproof*-designed room, but to address that boxiness the video talks about, in that small space, you will need a lot of both absorption and diffusion.

The front-rear spaces ("front" meaning where you are looking when you sing) because whatever bounces directly off the front wall will reflect back against all of the surfaces. The back wall will catch direct reflections and come back to the mic in the most direct way, but everything will catch and reflect some of that front wall surface. In that small of a space, I'd probably want to emphasize absorption with some good broad-band trapping covering most of that wall and at least some of the side walls from your standing/sitting spot forward. Some "clouds" directly overhead and a mix of absorption and diffusion on most of the back wall.
 
You've already built a *soundproof*-designed room, but to address that boxiness the video talks about, in that small space, you will need a lot of both absorption and diffusion.

The front-rear spaces ("front" meaning where you are looking when you sing) because whatever bounces directly off the front wall will reflect back against all of the surfaces. The back wall will catch direct reflections and come back to the mic in the most direct way, but everything will catch and reflect some of that front wall surface. In that small of a space, I'd probably want to emphasize absorption with some good broad-band trapping covering most of that wall and at least some of the side walls from your standing/sitting spot forward. Some "clouds" directly overhead and a mix of absorption and diffusion on most of the back wall.

If he puts a cloud on ceiling he loses another 4" which makes it 6'1" in height and with losing 8" in width and length because of panels on walls, he would have a room that he can touch all walls and a ceiling that is on his head. Don't know about you but I couldn't spend 30 secs in a place like that.
 
Well, I'm female - and pretty short (5'3") so I don't think that part would be too much of a factor. Pre-made vocal booths are much smaller than what I've been constructing (well, with my folks' help). I think the one my boss works in is 2 x 4 - the smallest Studio Brick model. It is tiny compared to what I've got and yet his doesn't have a boxy sound, and it's not covered in acoustical treatment inside, from what I can tell. Maybe some bass traps and a panel or two of acoustic foam IIRC.

Thanks so much for everyone's input. I'm still taking all this in and trying to understand everything. I had initially figured diffusers and sound absorption panels were the way to go. Then using only bass traps was mentioned so I am at this point very unsure about what to do lol I have some left over rockwool insulation panels that I was going to use to make the absorption panels and/or bass traps, so I've been researching the best/easiest way to construct those.
 
I have built my own Lynne and sorry for calling you a 'He'. I don't suppose you sound like Barry White either.

I sort out advise. Some not exact. I found out by trial and error and by costing myself more money. But I know what works.........for me.

Luckily I had more room. My booth is 10' x 6' x 8' high external with 100mm insulation all around and walls of 18mm osb. Lined with foam and I am experimenting with lower frequency absorption (materials). But the one I built is for my wife so low end not that important.
 
This is how the inside of his booth is treated. I don't know how much of this was already part of the booth itself and how much he put in (maybe only the bass traps? Not sure).

image0.jpg image3.jpg image4.jpg
 
Yes those 'holey' panels are to diffuse the sound waves. They break them up so any sound is easily absorbed and not bouncing back strongly towards the microphone.

Basically most materials will absorb sound to a greater or lesser degree. When all's said and done you go with .....what is available....what you can afford/do for yourself....what is practicable.

For example.....some voice over people claim they use a cheap $50.00 mic and a couple of old duvets. I don't know???

Suppose if that's all you need the Neumann and the like just wouldn't exist.

All I can say there is a lot more to it than that and it works out a lot more money as well if you want to do the job properly.
 
lol - it's perfectly okay, Orson - no worries. It's not like my name (which is the pseudo I use for book stuff) gives it away.

And yeah, sorting out advice is what I often have to do. And I try to sort it out in a way that makes sense to me. Sometimes it takes me a while - haha

I would have gone bigger if I could, but I am limited as to how much space I've got, so I did the best with what we had. It's a huge step up from what I was working in before, which was literally a little cubbyhole space underneath some stairs. Very small and uncomfortable. This one will be huge compared to that.
 
Ahhhh - so those are diffusers then! I had no idea. I'm telling you, I'm very much a NOOB to some of this this :p I mean, I know what bass traps look like, and acoustical foam, but I'd have never guessed those holey panels were like a diffuser. derp
 
Ok Lynne in a nutshell. According to the experts of which I am not. You started off with a bad size as you never have a room which is the same measurements all round.

What I have learnt is that drywall/plasterboard echoes like hell and osb board is stronger, softer with sound but more expensive.

I preferred proper acoustic foam over cloth covered fibreglass/rockwool inside such a small space and I am trying more natural materials for any lower frequencies the foam does not take out............Like I say you go with what is available and what you can afford.

The holey board I would try depending on cost etc.

When you sort your room out. You will need ventilation to get rid of moisture from you and to provide you fresh air..........Again what you can do yourself etc...........A good fan is approx £$50.00 but then you have to make it silent.

You can spend thousands and basically never stop.

First of all I would get the room quiet and then work out cost of sound treatment......foam panels or rockwool panels etc.
 
The panels could be made from a board material and possibly backed with absorbing foam or other.
 
I was trying to find that holey diffuser stuff but can't locate it so far. Most diffusers I see are totally different looking than that. Which is one of the reasons I had no clue those were diffusers. Something like that would actually be preferable than what I was looking at (which was this - https://www.amazon.com/gp/product/B0798SJ77F/ref=ox_sc_saved_title_7?smid=A3OLQ5TI0FA06O&psc=1).

My room isn't totally uniform as far as the "same" measurement. The angled doorways on each side break up the actual measurements into uneven ones. I was just giving rough figures off the top of my head to present an idea as to how large the working area was.
 
As far as I know. Diffusers are designed to do a particular job and deal with certain frequencies depending on their design. The Amazon example I haven't a clue as what it is supposed to do.
 
My room isn't totally uniform as far as the "same" measurement. The angled doorways on each side break up the actual measurements into uneven ones. I was just giving rough figures off the top of my head to present an idea as to how large the working area was.

If your room is already finished then you need to work out costs of all sound treating materials.
 
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