If you want your recordings to take the next step when it comes to overall sound quality and feel, you should definitely consider having a vocal booth or at least something that closely resembles one. A vocal booth is a huge part of a recording studio, and usually entails a portioned off, isolated and enclosed area from the rest of the studio in terms of sound transmission. It may provide a worthwhile reduction in the amount of unwanted room reverberation that is captured, extra annoying frequencies that may be picked up by our sensitive condenser mics, or grab ambient noise from even outside of the studio at times.
Vocal booths are used to provide a space to record solo instruments, vocalists or voice over, without the recording being compromised by other elements like sound, echo coming from the room. Vocal booths can range from $500 to $5,000 depending on the materials used and how large of a space you want to create.
- How big of a booth?
- Materials used
- How to eliminate unwanted sound
- Placement issues
Creating a Vocal Booth
Vocal booths are generally smaller rooms designed to accommodate one or two people. Knowing the size of the vocal booth first and foremost is going to be critical. When building one, the dimension of the room combined with the quality of the acoustical materials used will control the reflection of sound. A typical vocal booth generally produces waves between 150 Hz to 350 Hz.
Most vocal booth sizes range from 3’ x 4’ to 4’ x 6’, but you don’t need to be strict here — the bigger the better depending on your needs, while going as small as possible can help reduce room for error. These sized rooms are great for vocals, amps and acoustic guitars. A six by nine feet vocal booth would be fine for recording a drum kit. The recommended ceiling height would be eight feet. So the questions for you will include: is this going to be just for yourself in a home studio? Perhaps an additional singer? An entire band?
Do the numbers first. Map out the room’s square footage and get organized. Write it all down or create an excel sheet of every inch that needs to be covered. We’re not number people ourselves and it may seem tedious, but just buying a bunch of sound proofing on Amazon and slapping it to a few parts of your wall isn’t going to be too effective. Take some time to get it correct.
The materials used to build vocal booths all provide sound isolation from the outside and sound absorption from the inside.
Ideally, you would want to build a vocal booth within a room where the walls are separated from the studio. The same goes to the floor. Typically, professional studios have floating floors which refer to the installation method where the floors do not need to be nailed or glued to the sub floor. A lot of home studios don’t worry about the floor and that can be fine if you’d like, but we’re talking about 25% of the entire vocal booth here. We’d try to cover your floor if you can. You can always get away with leaving it be at first and perhaps upgrading later if you want.
Wall and ceiling construction can be made with various degrees of isolation. Standard wall construction with one layer of gypsum board on each side of the wall would be the minimum. You can increase the isolation by applying a second layer of gypsum board to increase the mass. Moving on, the walls can either be made with staggered stud, or double walls.
A normal wall will have 2×4 lumber used for framing separated by 16 inches. The 2x4s will be attached to the bottom and top plates which are 4 inches wide. In a staggered wall, the top and bottom plates are 6 inches wide. The 2×4 studs are placed alternatively on each side of the plate. The gap between two staggered studs is 12 inches. With a staggered stud, you would achieve an STC (Sound Transmission Class — a way to measure the effectiveness of all of this subjective matter) of 48.
To give you an idea, at STC 45, loud speech will not be audible and at STC 50, loud music at a mid and high frequencies will be faintly heard. By adding more drywall and damping compound, which is a sound deadener, a higher STC can be achieved (about an STC of 62, which is very good). With a staggered wall, you would only lose 10 inches of space on each wall.
A double stud wall is two standard wall frames joined together. Instead of nailing them together, they have a small gap between each wall frame to have as much decoupling as possible. In this case, we have two frames of 2×4 studs with a gap in between. The overall thickness of each wall, given a two inch gap, would be 10”. With a double stud wall, we get an STC of 60 which is great and most sounds will not be audible. A double stud wall would take 4’ reduction in length and 4’ reduction in width. If you have enough space to spare, a double stud wall would be ideal.
When choosing soundproofing materials for the walls of a vocal booth, choose a minimum of 2” thick of high quality acoustical foam material that works in the vocal range. In addition, as sound naturally gathers in corners as the walls and ceiling combine, building a highly effective broadband absorber and placing it at all the tri-corners of the room would be a wise decision as just a cherry on top to really seal the deal.
To be able to explore ways to eliminate unwanted sound, we should first talk about types of frequencies.
High frequency noise like chirping birds, ringing telephones, barking dogs, is made of low energy sound waves. These are easily eliminated.
Low frequency noise like traffic, heavy footsteps, is made of high energy sound waves and more effort is required to reduce it.
The followings are ways to eliminate unwanted sound:
Sound waves are cancelled when they meet an ‘inverse phase’ of that same wave shape, which is called destructive interference. This noise cancellation system works when a sound wave is emitted with the same amplitude, but with inverted phase, also known as anti-phase, to the original sound. The waves combine to form a new wave in a process called interference and cancel each other out (which is called destructive interference).
Some materials that have hard, smooth or rigid surfaces like stone, metal and hardwood have high sonic reflectivity. When the sound waves hit those materials, it bounces right off. This is especially useful for high frequency sounds.
Some porous materials like Styrofoam will absorb different frequencies instead of reflecting it. These will especially absorb high frequency sounds and won’t hurt adding here and there in your wall layering.
Different materials reflect and/or absorb different frequencies. That is why building a wall with many layers of materials with different properties is a good way of disrupting a broad spectrum of noise.
After deciding the size of the room and wall construction, you should consider some of the issues that you might face as you develop the design.
As vocal booths are small in size, they are best accessed via a door swinging outward. Reason behind it is that if the doors are accessed swinging inward, then you will have difficulty getting in and out because there is not enough space. When you install the door, use an industrial strength weather strip to seal all air spaces around the door; the sides, the top and the bottom.
Windows are bad. Most of the time, especially if it’s looking out into the outside window. It’s always recommended to have zero windows in a studio. In regards to the actual booth however, many like having visibility of their recording source. The main reason a vocal booth will need a window is so that the musicians, producer or orchestra leader will have a visual contact of each other. So if you plan to build an indoor window in the booth itself, you should position it at an angle so that the person inside the vocal booth can see the others. Moreover, the window must not let any sound through.
The window material should be made of laminated glass of at least half an inch thick. This will reduce the vibrations on the glass itself. You would want to install two pieces of them with their frames and with two inches of space between each of the individual glass pieces. Glue the place where the window meets the frame with an acoustic glue and use an acoustical sealant around the inside and outside edges of the glass-frame contact area.
As you already know, light is a source of heat. As the vocal booth is small, it tends to get warm quickly. So, using a low energy lighting would be the best solution. In placing lighting, you should avoid using dimmers as they often generate electromagnetic fields that can introduce hum and buzz into the recording.
If you’re doing this from scratch and are literally mapping out outlets, this is a whole different ball game. When placing electrical outlets, make sure they are easily accessed. Plan ahead and have an idea of where your equipment is going to be placed so that you can install the outlets high enough to make connecting amps and effects for example, efficient. Also, make sure all outlets are sealed to stop air going through.
Again, as the vocal room is small in size, they tend to get warm very quickly and keeping fresh air in the room is essential. We can’t tell you how many times we’ve had crazy sweats after a session. We’ve also had a few of our friends literally break headphones due to sweat!
An ideal way of introducing air flow would be by building air intake down low at floor level and outflow mazes exiting high up at the ceiling using natural convention to help the system. An example of this would be two or three low speed fans with a larger outflow port rather than a powerful fan that will spin at a higher speed.
Where to build a vocal booth:
To improve the overall effectiveness and reduce the cost of building a vocal booth, it is recommended if possible to build it in a basement where the walls are made of concrete. If that is not a possibility, then choosing an isolated room where the walls are dense, away from laundry appliances, water pumps, etc., would be a wise decision. We can’t always have the perfect setup of course, especially if you’re making a home studio, but if you have some options, go as isolated as you can.
Size, materials used for the walls, and soundproofing are all important in the production of a desired sound. Plan,. plan, plan!
Determining the size of a room depends on what you are accomplishing. To determine the size of a vocal booth, you should first decide what you’re going to use the vocal booth for; whether it is for vocals, instruments, drum or band. You should also decide what equipment and musical instruments you are going to use inside the vocal booth. You may be limited to the space you already have as well, which is fine. Even just a few slabs of soundproofing can go a long way, but if you’re taking a lot of time and resources to get this done, we recommend doing it as best as you can.
The quality of the materials used also plays an important part in the quality of sound production. Thicker walls with higher quality soundproofing materials ensure a better sound quality. The higher the quality of the materials, the better the sound quality of your recordings.