John Sayers' Recording Studio Design Forum Archive

Hi everyone - first time caller (as they say on the radio!)

About this time next year I hope to be moving house and building a voiceover booth. It's a process I've done six times before. I'm hoping this will be my final move and my "forever booth", so it's vital I don't repeat my past mistakes.

Well, I've got plenty of time to think things through before the move, but in preparation I wanted to pose a couple of general questions about voiceover booth acoustics:

I know that all experts agree on this; the bigger the booth the better. Or better still, no booth at all. But, in practice, is there a minimum cubic size to shoot for? A size that we could confidently predict will work well for male and female voices (given proper internal treatment, of course) We'd need something that's big enough for two performers, if that helps.

Secondly, I know that conventional wisdom favours almost 100% absorption coverage. Obviously this results in a very dead, acoustically "tight" space. Trouble is that very dead booths can be oppressive. Is there any method or sense in adding back a little liveliness to make the space more comfortable to voice in and at least give some sense that the recording is coming from a room - not an anechoic chamber?

Lastly - and this may be an oddball thought: rather than build a booth as flat as possible, would it be feasible to design a room that simply sounds great on spoken word? More through luck than judgement, one of my previous booths just felt very encouraging to perform in. Almost like it had a helpful, springy resonance in the upper bass.

Apologies if any of this upsets purists. Without getting too specific on anything, I was just hoping to start a general discussion about great booth design.

Hi there " Dayo", and welcome!

I've got plenty of time to think things through before the move,

That is really REALLY good! You have no idea how many folks we get saying things like "How do I build a studio? I'm starting tomorrow"...

But, in practice, is there a minimum cubic size to shoot for?

Not really, no. Unfortunately! It would be nice if there were a simple room saying "Male vocals need 19.387 cubic meters, and females need 17.165". But it ain't so.

Having said that, I guess one way of thinking about it would be to design a booth that has modal support down to at least the lowest frequency of interest, and smooth modal spread from there up. Speech is generally considered to be 300 Hz to 3000 Hz, but in reality singing goes a lot lower than that. Male vocals can get down to 90 Hz or so, for a really low bass voice. Based on that criteria, all of the dimensions of the room would have to measure at least 2 meters. But to get a smooth spread, you'd need more than that. I just did a couple of quick tests, and the smallest room that meets that criteria would be about 2.4m high (normal ceiling height), 3.3m long, and 2.75m wide. Floor area is 9 m2, and room volume is 22 m3. Not exactly a booth! That has modal support down to 49 Hz, and smooth spread from about 82 Hz upwards, with at least two modes for each note.

OK, so that's just me thinking out loud: Don't take it as Gospel truth! I've seen much smaller booths that actually sound half decent, and if you are only ever going to record spoken word, or female sopranos, then you could go smaller.

One caveat: the smaller it is, the more treatment it will need. Very small booths have to be pretty dead to be usable, and "dead" is not nice to work in!

We'd need something that's big enough for two performers, if that helps.

Well, if it is for two people, then I would definitely consider something like the above dimensions. (Unless the two people are REALLY "close" friends!)

Secondly, I know that conventional wisdom favours almost 100% absorption coverage.

That's only because those booths are so small that you have no choice. If you make it larger, then you can indeed liven it up a bit. You could even make the acoustics variable, with folding or sliding panels that reveal or hide absorption.

Is there any method or sense in adding back a little liveliness to make the space more comfortable to voice in and at least give some sense that the recording is coming from a room - not an anechoic chamber?

With a very small booth, no, not really. The modal spread is so mangled that it has to be killed, very dead, then shot repeatedly, hung, drawn, quartered, beaten, drowned, run over, and finally nuked, so that it is beyond "dead" !

Lastly - and this may be an oddball thought: rather than build a booth as flat as possible, would it be feasible to design a room that simply sounds great on spoken word?

Yep! If it is big enough.... See above ...

More through luck than judgement, one of my previous booths just felt very encouraging to perform in. Almost like it had a helpful, springy resonance in the upper bass.

How big was it, and how was it treated? If you could find out the dimensions, you could try duplicating it.

But overall, I'd go for the largest booth that you can fit in (you didn't want to hear that!), treated for a neutral sound, and with variable acoustics so you can make it more "live" or more "dead" as needed.

My $0.02


- Stuart -

Stuart - thank you x a zillion.

Will digest your thoughts and post back.

Exactly the kind of info I needed. Great stuff.