John Sayers' Recording Studio Design Forum Archive

So, i purchased vocal booth plans online. I'm watching the video on the construction of the floor and it just does not look right to me. Does the construction in the attached picture look legit? Couldn't i just frame the floor like any other floor?

Hi there "nemesis808", and Welcome!

You are right: it definitely does not look right!

In fact, there are several things wrong with that. Firstly, the booth is square!!! Which is one of the worst possible shapes, acoustically. All of the modal response issues (standing waves) that occur in the "width" direction will be exactly matched by all of the modal response issues that occur in the "length" direction. In other words, those modal issues will be double the intensity, and will reinforce each other. The peaks will be twice as intense, and so will the dips. Plus, since there are now a lot fewer axial modes to go around, the spread will not be smooth.

One of the most basic rules of acoustic room design, is to ensure that no two dimensions of the room are the same, or multiples of each other, or within about 5% of each other. A square shape room is the third worse shape possible. A cube is the second worse, and a sphere it the worst.

So whoever deigned that "vocal booth", clearly doesn't know much about acoustic design!

The second major issue, is that the image is showing a raised floor! Why on earth would anyone put a raised floor in a vocal booth, of all places! WHY???? A raised floor is, by definition, a resonant system. It WILL resonate at certain precise frequencies, that can be calculated easily. So whenever that frequency happens to occur in any sounds inside the booth, or outside the booth, the floor will resonate in sympathy, and transmit that tone right through to the other side. It's not a good idea to have a tuned resonant box as the floor in your booth...

There's also the additional issue of impact resonance: drop something on that floor, and it will vibrate/resonate. Step on it: same thing. Put a mic stand on it, and the mic stand will pick up all those vibrations, and send them directly to the mic...

So whoever deigned that "vocal booth", clearly doesn't know much about resonant systems, acoustic isolation, vibration, microphones, flanking paths, or studio floors either...

Not only is the floor a resonant system, it is not even needed at all! That's a myth. A very persistent myth, true, but a myth nevertheless. In the vast majority of cases, no floor is necessary, least of all a raised, resonant floor. Studios only need raised floors for very special circumstances, and this is very unlikely to be one of them. Apart from anything else, that wastes a lot of precious ceiling height...

Where are you planning to use that booth? What type of floor will you be putting it on?


I'd say that you should probably totally ignore whatever those plans say, and look around the forum for vocal booth designs that actually do work, and have been proven to work in practice. There are many examples. Use the "search feature", and you should be able to find several.


- Stuart -

Thank you so much for the response! I've just got back to reading your post and im searching the forum and doing some research. So, while i search and learn i hope you don't mind some questions.

In fact, there are several things wrong with that. Firstly, the booth is square!!! Which is one of the worst possible shapes, acoustically.

What shape would you recommend? I've read that the diamond shape is one of the best. Is that correct? Is there anyway to take a square booth and optimize it so that "no two dimensions of the room are the same" as you put it.

The second major issue, is that the image is showing a raised floor!

Would it make any difference if the cavity was filled with "ROCKWOOL" and used Green Glue sandwiched between two layers of 1/2 inch OSB top and bottom of the floor?

Not only is the floor a resonant system, it is not even needed at all!

So what would i use for a floor?

Stuart. Thanks for the help man it's MUCH appreciated!

What shape would you recommend? I've read that the diamond shape is one of the best. Is that correct?

As long as the length, width, and height all differe from each other by at least 10%, then you should have a reasonable ratio. In other words, if the height is 8', then the width should be more than 8'8", and the length would then need to be more than 9'8". The booth can still be rectangular, or it could be diamond shaped if you prefer.

Would it make any difference if the cavity was filled with "ROCKWOOL"

It would help a bit,bit not much. That would help to damp any internal resonances, but it would not do much about the higher MSM resonant frequency, which skews your low frequency isolation.

So what would i use for a floor?

Whatever is there for your existing floor at present! After the booth is in place, you could maybe put down some laminated flooring, which can look very nice and is also good for acoustics.


- Stuart -

Soundman2020 wrote:

What shape would you recommend? I've read that the diamond shape is one of the best. Is that correct?

As long as the length, width, and height all differe from each other by at least 10%, then you should have a reasonable ratio. In other words, if the height is 8', then the width should be more than 8'8", and the length would then need to be more than 9'8". The booth can still be rectangular, or it could be diamond shaped if you prefer.

Would it make any difference if the cavity was filled with "ROCKWOOL"

It would help a bit,bit not much. That would help to damp any internal resonances, but it would not do much about the higher MSM resonant frequency, which skews your low frequency isolation.

So what would i use for a floor?

Whatever is there for your existing floor at present! After the booth is in place, you could maybe put down some laminated flooring, which can look very nice and is also good for acoustics.


- Stuart -

I'm even more confused now. So the wall sit directly on the floor? How can i get good isolation that way? almost every design i've seen has some sort of floor.. including ones I've seen on auralex.com! Is there ANY design with dimensions you can point me too?

What is your existing floor made of? And what is underneath that floor? THAT is the key issue here.

- Stuart -

FYI - There is a vocal booth design at the top of the 'studio design' listings.

Scott

rockindad wrote:FYI - There is a vocal booth design at the top of the 'studio design' listings.

Scott

Im actually building that booth now! Im pretty excited about it

Soundman2020 wrote:What is your existing floor made of? And what is underneath that floor? THAT is the key issue here.

- Stuart -

I'm in a building that's a historical landmark (first bank of Italy which then became BofA!) I'm on the mezzanine floor (just above the lobby) and my floor is what seems to be a concrete slab that i put this peel and apply faux hardwood flooring on. Attached are a few photos

The hardwood photos are looking great you can add a wool carpet on it so that the shine of the hardwood flooring are maintained for a longer time, you can check some carpets from [SPAM REMOVED BY MODERATOR - SPAMMER BANNED]