Voice over booths are a popular add-on for most studios as it allows you to record the voice in an acoustically dead environment so that it can be electronically enhanced to create the right feel to meet the application. For instance, someone talking inside a gymnasium will sound very different from someone talking in a hallway or a restaurant. When the voice is recorded without ambiance, reverb and echo can be added during post production to fill the need. Building an effective voice over booth is not difficult. These are some practical guidelines to follow:

Step 1: Determine the size
How big should it be? Well that really depends on how many people will be using it at any one time. If you plan to use your vocal booth for solo singing, you can get away with a relatively small booth. If on the other hand you plan to record dialogue, you may want a room with enough space to accommodate two or even three actors. A typical voice over booth will range from 4'x4' to 4'x6' and up. It must be big enough for mic stands, music stand and if you plan on it being used as an isolation booth, maybe even instruments (electric guitar, drums, bass…) Start by drawing a floor plan and see how it best can fit in your room. [image]

Step 2: Wall construction
Once you have decided on the shape and size, you have to consider the construction. Most studios employ offset stud walls to help contain sound and keep noise out. This is the best type of wall construction but it does mean that your walls will be thicker, especially if you use 2"x6" top and bottom rails. [image] If space is limited, consider using standard 2'x4' studs for the rails and the same for the walls by turning them sideways. This will save a couple of inches on each side. Adding a Barrier strip on the inside of the walls will further help reduce noise transmission. This barium impregnated PVC is very heavy and works best when hung relatively limp. [image] Double up on your sheetrock to increase the mass.

Step 3: Doors and windows
Sound travels via vibrations. This means that if the obstacle you have constructed to hold back sound can vibrate, sound will pass right through. The heavier the obstacle the more effective it will be at controlling sound. For the door, use a heavy solid core commercial door. If you choose one that has a window, make sure the window is also heavy. You should also consider doubling up the window with a second pane of glass. This will help keep noise out. Your window should follow the same rule. You also want to make sure you have a good industrial seal around the door so that sound cannot find its way through the cracks.

Step 4: Ventilation
Next you have to think about the ventilation. Your actors will not perform very well if they cannot breathe! So how do you get fresh air in without letting the noise through? The answer is: build a maze. Sound tends to be very directional so it has difficulty going through an acoustically treated maze. In essence, we have to create an indirect path for the sound to travel in and out of our voice-over booth. For air to flow, you need an intake and outtake. Heat rises, so the outtake is usually best if the exit port is up high. It is also easier (and often quieter) to such air out than it is to blow air in. And the larger the ventilation pipe, the lower the air velocity which of course means less noise. The intake pipe can be near the floor. An effective method is to build a passage way between the outside and inside while forcing the air to go around a few corners. Treat the inside of your ducts with 1" thick acoustic material. This way, sound will be absorbed while the air continues to flow. On the outtake, do the same only add an exhaust fan. Consult your local building supplier to find a fan that has plenty of draw while being extra quiet. If you ca control the speed it is a huge bonus!

Step 5: Electrical and audio wiring
In addition to your fan, you will need to have some lights. The easiest solution here is to mount standard electrical outlets inside your room and use plug in arm lamps. Make sure that the electrical outlet boxes on the inside and outside are distanced from each other so that sound does not transmit from one to the other. Adding some insulation around the outlets will also help contain sound. The mic connection is best done using a standard 4"x6" nema electrical enclosure and by having a custom panel made with 2 to 8 XLR connectors and two or more ¼" jacks for return audio.

Step 6: Acoustic wall treatment
Most voice-over booths tend to be heavily treated to eliminate any reverberant field. Although you can get away with 1" material, you are far better off to use 2" thick material to help tame some of the mid range. Broadway panels work great for this! Especially if the inside walls are made with 12" increments. This way, you will have less cutting and fitting to do. To control the lower mid range, Cumulus triangle traps are highly effective. Best of all, they are easily mounted and completely out of the way.