IN THE BEGINNING, there was dirt. Dirt is great for sound. It doesn't make noise and sound doesn't bounce off of it.
THEN MAN CREATED NOISE. That was okay until we created sensitive microphones that pick-up every little noise - even computer fans, distant planes, and shirt ruffling noise.
WORSE, WE BUILT HARD SURFACES, such as walls, corners, and music stands that bounce sound around... especially into sensitive microphones.
THE PROBLEM? Producers and engineers came to expect that voice over recordings were void of noise and bouncing sounds.
THE CHALLENGE? Building a home studio out of dirt is not practical.
FORTUNATELY: With thought and creativity, a quality, suitable, comfortable, and marketable voice over studio can be built for little to no money, almost anywhere you want. To boot, demand for home voice over studios continues to increase.
THIS ARTICLE: From location to claustrophobia, even with loud kids, starched shirts, air conditioner vents, and hard surfaces, this article will list considerations that will help you design and build a competitive home studio.
NAME: The room you record voice over in is interchangeably referred to as a booth, sound booth, sound room, isolated room, iso room, and iso booth.
PURPOSE: Voice over producers and engineers generally expect a recording that contains only your voice: no additional noise, and no echo (known as reverb, which is short for reverberation).
SOUND WAVES: are invisible waves that transmit sound. They pass through the air and carry, what our ears and brains convert to sound. They also pass (vibrate) through adjoining surfaces (wall to wall). Understanding 1.) the frequency and volume of sound waves (see sound proofing below) and 2.) how they travel (see sound absorption) is essential for building a studio.
SOUND PROOFING: Like water, sound waves find their way through just about anything. Imagine your kitchen floor full of water. Now imagine a very small hole in your floor. Eventually all water will pass through. Likewise with sound. A very small opening in your studio will allow too much sound to pass through to the microphone. It is therefore necessary to block all sound from entering your studio.
High frequency (high pitch) sound waves, such as those that carry cymbals, flutes, and the “clarity” portion of human speech, as well as low volume sounds, are very small, and almost any blockage will stop them, such as thin walls, glass windows, and thick blankets.
Conversely, low frequency (low pitch) sound waves, such as bass guitar, drums, and the “resonance” of human speech, as well as loud volume sounds, are very large, and pass through many surfaces. Blocking these from your microphone is challenging.
So to block sound, the rule of thumb is “the more noise you need to block, the thicker your walls must be.” So if your studio is in a home, on a quiet street, without dogs barking and street noise, regular walls may be fine. (Perhaps you'll need to cover windows with a pillow, as glass is very thin and will let noise in.) If you have a medium noise entering your studio, try slightly thicker walls, or multiple thin walls (such as a closet (a room within a room)). If a lot of noise enters your studio, construct walls, ceiling, and floor of multiple layers of sheet rock (wall board), preferably that stagger and include air-pockets between each layer. Also incorporate acoustic door seals (to prevent sound from leaking into the booth from the door edges), rubber bushings attached to the ends of each wall joist (to prevent sound transmission from one surface to the next), and use acoustic sealant (as it remains soft (pliable)) and therefore mitigates sound transmission from one surface to the next.
SOUND ABSORPTION: Sound waves propagate in all directions and bounce off of surfaces...especially hard surfaces. (Recall the big echo caused by a basketball bouncing in an empty auditorium.) This echo must be totally eliminated for voice over recording.
Assuming your studio is sound-proofed, the only sound propagating inside your studio is your voice. The louder your narration, the more echo there will be to stop.
Soft materials such as foam (egg-crate foam), thick blankets, carpeting, acoustic ceiling tiles, and plush furniture are commonly used to eliminate echo. Try to cover every square inch if possible. Be sure to cover your music stand too - a piece of carpet or soft rubber matting on it generally eliminates your voice from echoing off of it.
If you narrate in low volumes, such as audiobooks, documentaries, some national commercials, meditation programs, etc., one or two inches of soft material on all surfaces should suffice.
If you narrate in loud volumes, such as the big booming voice in some commercials, certain promos, certain character voices, etc., you may require three of four inches of soft material on all surfaces.
SHAPE: While most rooms are square, sound booths should be anything but. In fact, the more angles, the better, as each angle helps deflect the sound, eliminating the possibility of “flutter echo” (sound that repeatedly bounces back and forth between two opposing surfaces).
If possible, construct your room with at least one angled wall.
LISTEN: Unless you have trained ears, you may not hear unwanted noise and/or unwanted echo. It is best, therefore, to record a sample and ask a studio to evaluate it. Do this before selling your home studio services to clients. Ask them to confirm that you recording is absolutely quiet and dry.
LOCATION: Your studio can go anywhere, as long as you ensure that it is sound proofed and echo free.
Below ground level (basement) studios are ideal, as windows rarely exist, and walls are usually underground. Walk-in closets are also good, as they rarely have an outside facing wall (architects tend to design homes so that closets do not take up potential window opportunities). Try recording in your car or mini van, as they are built to be quiet inside, and if parked inside your garage, they offer another layer of sound proofing.
If none of these are possible, it's time to build. Expect to pay a contractor between $1,000 and $5,000 depending upon your specifications. Another option is to purchase a pre-built (pre-fabricated) studio (see below).
SIZE: Determine how large your booth must be, and if possible, make it at least 50% larger. (One day you'll thank yourself.) Additionally consider how many people will record simultaneously in the booth (will you record dialogues? Will you record foley sfx (which takes up a lot of room)? Will you need a video/computer monitor to view while recording? Will you want a table for scripts, water, etc.?)). Be sure to account for the microphone and music stands. Will you stand or sit? (Sitting down is common for long recordings, such as audiobook recordings, but takes up more floor space.) Do you have claustrophobia? If so, go with a larger booth. Will you rent out your booth to musicians (who need larger spaces for guitars, keyboards, etc.)? Think about these things before you build.
WINDOWS: Windows are nice. They prevent claustrophobia, allow you to see a producer/engineer outside the booth, and allow you to view a video/computer monitor during the recording (in the event that you must match your voice to a visual while recording). However windows are thin, and therefore they let sound pass through. And windows are a hard surface, and therefore cause echo. Ideally, use a window... just make it small, and have prepared a pillow you can stick over it in the event that you must narrate a loud recording that cause more echo.
DOOR: Use a solid wood core door, or a metal door - and then cover it with a soft material to prevent echo. Incorporate acoustic door seals (or heavy-duty weather stripping) on all four sides.
LIGHTING: Be sure to have a well-lit sound booth, so there is no strain on your eyes. Preferably use a non-glare, non-heat producing light type. Note - most fluorescent lights produce noise, and unless you find one that is supposedly silent, stay away from fluorescent.
A/C: Have a number of electric outlets in your booth - so you can plug in a monitor, a headphone amp, lights, and anything you need.
AIR: Due to their small size and lack of incoming/outgoing air, sound booths become warm and musty after a while. Therefore, ventilation is a welcomed option when recording a long narration. Be sure, however, that the vents do not create any noise. One solution is to bring your central air conditioning into the booth - and run it on fan or A/C. Be sure to coat the inside of the ducts with sound absorptive material, and be sure that the ducts make many 90 degree turns (each 90 degree turn decreases the volume of air movement, from the vent, by half).
WIRES: Remember that wires (video, data, monitor, XLR, telephone, BNC, cable, etc.) should be run through one of your walls before you complete your studio. Using a door-knob drill to drill a hole through the wall, run all types of wires through it (you never know what you will need), and then seal the hole with acoustic caulking.
PRE-FABRICATED: Okay - want the easy way out? Purchase a pre-built (pre-fabricated) sound booth. Many companies sell these (look on-line). Try to purchase a modular one so that you can expand it (should you need to) and/or move it easily. Various quality levels, sizes, and options exist - including built in lights, windows, wire runs, and more. Expect to pay between $2,000 and $8,000 for a voice over quality one.
CONCLUSION: Building or purchasing a sound booth is a one-time event. Enjoy it. When done working, let your kids use it as a play room (allowing you quiet in the rest of your home).
Edge Studio offers private and group consultations on home studios and ProTools. Call 888-321-edge (3343) for details.