Dead Tracking Room Design

[bounty]

Hi guys,

I have a live room that I'm trying to make a dead as possible. It's primary use will be recording dialogue for animation and vocal tracking, it very occasionally gets used for guitar ect...

The walls are built from high density concrete bricks, the floor is poured concrete, I'm not sure of the exact ceiling construction other than it's covered in plaster, so I would assume that it's a stud ceiling stuffed with insulation. The ceiling is also sloped. The double doors are completely glass with a pvc edge. Below are the dimensions and an idea of shape.

Live Room face on.jpg

Live Room Top View.jpg

At the moment the walls are covered in 4' x 2' x 4" broadband absorbers, the floor has carpet on it and the ceiling is covered with 1'x1' foam tiles that are roughly 3" thick. I'm not quite happy with the results I'm getting from this, it's dead, but not dead enough and the frequency response throughout the room is sporadic.

My plan is to remove the carpet, lay down laminate or lino flooring over the concrete, build 4" thick stud walls (like in the picture above), build a flat ceiling on top of that and cover the walls and ceiling in fabric. Space, especially width is limited so I'm reluctant to use up much more than 4" on all walls.

I'm a little confused about what to do with ceiling. The way I see it is I have two options, either lay an even layer of rockwool over it, or stuff it completely. So would it be better to have an uneven air gap or an uneven amount of rockwool? Any other suggestions are welcome.

Will 4" coverage around all walls with the use of movable baffles to help with any reflections from the doors be enough or should I look at including an air gap and membranes into the walls?

Finally the floor. As I understand it, acoustically a concrete floor is not a problem as long as the ceiling is suitably treated. Given that the goal is to make the room as dead as possible, should I look at building a floor or will I get the desired result by just covering it in lino or laminate flooring?

Materials budget is roughly £500-£750 with all the labour done by me.

Any help/advice/point me in the direction of some other good resources would be greatly appreciated.

[Soundman2020]

Hi there " bounty", and Welcome!

My plan is to remove the carpet, lay down laminate or lino flooring over the concrete,

Good start! The carpet is not doing anything to help you, and is likely actually harming the acoustics. Carpet has little use in acoustics.

Build 4" thick stud walls (like in the picture above), build a flat ceiling on top of that and cover the walls and ceiling in fabric. Space, especially width is limited so I'm reluctant to use up much more than 4" on all walls.

You could do that, but it might be easier to just build acoustic panels for the walls, and hang clouds from the ceiling.

I'm a little confused about what to do with ceiling. The way I see it is I have two options, either lay an even layer of rockwool over it, or stuff it completely. So would it be better to have an uneven air gap or an uneven amount of rockwool? Any other suggestions are welcome

If you want a very dead room, then I'd put at least 6" (15cm) of OC-703 up there, then hang clouds below that, as needed. The clouds could be hard-backed, and also could be steeply angled, so help with the modal issues.

Will 4" coverage around all walls with the use of movable baffles to help with any reflections from the doors be enough or should I look at including an air gap and membranes into the walls?

If you do the entire room in the same thickness, type, and density of insulation, you'll be treating the same frequency range everywhere, to the same extent. That's probably not what the room needs. I would vary the depth and angle of the absorbers on the walls, and I would put deep bass traps in at least some of the corners.

Finally the floor. As I understand it, acoustically a concrete floor is not a problem as long as the ceiling is suitably treated.

Correct! In fact, it's difficult to find a better floor, acoustically. That's about as good as it gets.

Given that the goal is to make the room as dead as possible, should I look at building a floor or will I get the desired result by just covering it in lino or laminate flooring?

Why do you want the floor dead? That isn't what your brain expects. Psycho-acoustics (the science of how the ear and brain perceive sound) show that it is better to have a solid, hard, reflective floor to give the brain a good acoustic reference point for determining directionality, spatiality, etc. Without a reflective floor, your ears have o way of determining which way is "up", acoustically, which is mildly disorienting. If you have ever been inside an anechoic chamber, you'll know how unpleasant that can be after a while.

You don't have anywhere near enough ceiling height in that room to be able to make the floor dead anyway, and you don't have the budget either, so just leave the floor as it is, as bare concrete, or with laminated flooring, linoleum, ceramic tiles, or similar on top. If the room is still too live after you do all the rest of the treatment (unlikely!) , then experiment with a couple of small throw-rugs of different thicknesses, right under the spot where you will be playing/talking/singing.

Any help/advice/point me in the direction of some other good resources would be greatly appreciated.

Before you do anything in that room, first do an acoustic test to see how it is performing right now. You need to know what the response and decay are looking like right now, in order to determine what you need to do to the room to make that go the way you want. So download REW (it's free), set up a good speaker with flat response, set up your measurement mic, and run the process. Post the resulting MDAT file here, and we can help you analyze it, to see what the problems are right now, and how to fix them.

You should also decide on just how dead you want the room to be, and what sort of decay curve you are looking for. What one person considered "just right dead" might be way too live for another person, and overwhelmingly, depressingly "dead" for a third person. For example, if I suggested a decay time of 200 ms, rising in the base and falling off in the high end, you might consider that "wonderful", or "way too bright" or "thuddingly dead". You might actually want 300ms flat, or 100ms bright, or 50ms dull, or whatever.

But do be warned: a very dead room sounds terrible, and is uncomfortable after even short periods. Your brain is not accustomed to it at all, since it pretty much never occurs in nature, and it doesn't like it very much. It also doesn't sound very good on recordings.

- Stuart -