How to Soundproof a Room, According to a Professional Sound Engineer

Soundproofing is the act of isolating a space from external sounds. Soundproofing entails what the pros call “sound acoustic treatments”—the practice of tuning a recording room to sound natural, since every space has an acoustic signature. It allows artists to record usable audio independent of what’s happening outside.

Continue reading for additional studio soundproofing ideas, how-tos, and need-to-know terms.

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When recording voiceover, a quality recording depends on the environment, materials, and performance—and the consistency of all those elements. Soundproofing helps maintain this consistency by eliminating external sounds from your recording. If you need to interrupt your voiceover every few minutes due to external noise, or postpone your recording session to the next day because of sound polluting the room, it will be difficult to maintain the same sound throughout the recording. Much like acting, a quality voiceover performance requires concentration, skill, and a controlled, stable environment. Soundproofing is the key to bringing quality sound to any work, whether you’re submitting an audio audition or recording for a new job. 

“I always say you need to put a lot of effort into recording a human voice, because it’s really something that carries a lot of emotion,” says Jean-Yves Münch, a recording engineer with more than three decades of experience working in film, documentary, music, and immersive media. “People are very sensitive to these details. They’re very subtle, but very important, especially for the human voice.”

Fully soundproofing a room involves placing soft, light materials on the room's surfaces—walls, ceiling, and floor—to absorb sound. Not all voice actors have the means to create a fully soundproof voiceover studio, so it's important to consider other factors as well:

1. Choose the right space. Start by choosing the right space, like a home office or bedroom with few or no windows—not your living room with large, single-pane windows and traffic on the other side. In some cases, even a sizable closet will do the trick.
2. Consider the room's surroundings and other external factors. From there, soundproofing isn’t just about adding components to a room to optimize sound. Whether you’re recording in a decked-out home studio or a soundproofed room, you should still consider other factors such as time of day, external stimuli, and a room’s natural acoustics.
3. Consider the timing of your recording. If you have trouble consistently controlling external noise with your soundproofing materials, aim to record when the noise is not present. Try recording at night when your neighbors are asleep and there’s less traffic on the roads, or even early in the morning. If you have quality insulation, ideally, you can work whenever inspiration strikes, but timing is still a strategic part of soundproofing. 

“You need to be sure that when you’re ready, your recording is going to work exactly the same way when you press record. Otherwise, recording is going to be a problem for you,” notes Münch.

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1. Absorption

This is when you use something heavy to absorb the energy of external sounds. Insulation will stop low frequency sound, such as outdoor traffic, from coming into the room. By using more mass, you can soundproof your studio more effectively.

2. Damping

It’s very helpful to have absorbent surfaces in your room. Heavy carpet, drapes in front of windows, and furniture (a bed, couch, pillows, etc.) are a few of the soft, heavy materials that will dampen sound. However, if your room is too dampened, you should add a little reverb when editing your recording, so it actually sounds like you’re in a room—otherwise it could give off an artificial sound quality.

3. Decoupling

This is when you build a wall in front of a wall in order to create space between yourself and any noise pollutants on the other side. This is more of a heavy-duty method, but it’s useful if you’re building out a soundproofed studio and dealing with a lot of external noise.

4. Filling gaps

Make sure you’re filling slits and small holes in any barriers. Put seals on windows, cover cracks in walls, fill in angles of walls, and treat these well. Quality soundproofing involves a cocktail of sound absorption, diffusion, and reflection. 

Once you’ve chosen a spot, identify where external noise is coming from. It may be a neighboring wall, traffic, your building’s hallways, or elsewhere. This is when your different ideas for soundproofing begin to take shape. Noise travels through air and objects. While transmission through solid barriers is more difficult to tackle (think of an upstairs neighbor who’s stomping their feet), beginning with air transmission (like a dog barking down the block) is easier. So start by putting plastic seals on any big windows with a lot of outdoor noise.

To tackle sound coming from inside your building or from your neighbors, a great insulation trick is adding bookshelves filled with books to your studio. Not only will they treat your room’s acoustics, but they will also break up the smooth noise-carrying walls with books of different sizes and shapes. If you’re open to investing a bit more money and time, consider building a decoupling wall by putting an additional wall in front of the first wall and filling the space between them with insulation. Make sure your wall is waterproof to avoid any mold issues, and that it has quality, filled joints at the corners with caulking.

One common misconception around foam panels for soundproofing: They will treat and help improve the sound quality in your room by reducing echo and breaking sound waves. In reality, they won’t contribute much to soundproofing. However, they’re a good addition if you have a lot of hard surfaces in a room.

Another soundproofing myth Münch quickly debunks? “You might have heard about gluing cardboard egg boxes all over a room for soundproofing. I’m here to tell you that doesn’t work. It’s very ’70s.”

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As you might suspect, the financial costs of soundproofing a home studio can vary based on several factors. At the higher end of a budget, you can expect to spend between $2,000–$5,000 per room. This means going all out: installing soundproof windows and doors, and building insulated or decoupling walls for a 120 square foot room. 

On a tighter budget—where you might simply add seals and drapes over windows, place bookshelves against your walls, and cover any cracks—you’re looking at closer to $300–$500 for a similarly sized room. Of course, this varies on factors like the cost of goods in your area, how much work actually needs to be done (sealing one window will cost less than sealing four), and additional labor costs. Start by making a checklist of what needs to be done. Look at the cost of materials from either your local hardware store or a larger home improvement center, and go from there.

A final option, notes Münch, is to spend little to no money at all. “Move around your existing furniture and rugs to optimize the space for soundproofing, and make use of the materials you already have. It might not be optimal, but it can be effective if you find the right combination.”

Beyond the physical materials you might use to soundproof a room, investing in recording hardware can also help. 

Portable sound booths are one option. They create a shield around a microphone to dampen the room’s sound and can also be moved from place to place. The brand Kaotica offers a version of this device. In terms of shops with great additional recording and soundproofing resources, Münch recommends sE Electronics (“Their products are classic, and usually super portable,” he says) and Sweetwater as great brands for recording hardware.

As a final note, Münch emphasizes that anyone soundproofing their home studio should ask themselves how often they’re going to use the soundproofed room. “From there, you can see how much of an investment you’d like to make,” he says. “If you’re using it often, from a professional standpoint, it might be a good idea to rent a studio, versus attempting to soundproof a room that has a lot of problems. Practicality should be key.” 

So there you have it! By applying these helpful tips, you’ll be equipped with the right tools and knowledge to soundproof your home studio. You’re well on your way to deliver quality, effective voice recordings for any voiceover acting or at-home recording gigs you may land.