Soundproofing

Not every home has a media room. This room is dedicated to enjoying video games, shows, movies, and music. It can handle an intimate group — just the two of us — or a larger group — a Rock Band party. One way a media room differs from a family room with a TV is the extra effort put into isolating it from the rest of the house. As much as possible, activity in the media room shouldn't disturb the rest of the house.

Basics of Soundproofing

Let's start with a quick review of sound. Sound travels via vibrations in air and solids (and liquids, but houses generally aren't built from liquids). When a sound wave hits a wall the wall will vibrate, which will cause the air within the wall to vibrate, and transfer sound to the other side of the wall. The sound wave vibrates the studs in the wall, providing a second path to the other side. There are many ways to decrease the amount of sound transferred:

• Decoupling elements: If the drywall on the inside of the room is not directly connected to the outside of the room, then there will be no solid pathways to transfer sound.
• Absorption: Loose material in the empty spaces of the wall help absorb and deaden the sound attempting to travel through the air cavities in the wall.
• Adding mass: Heavier materials require more energy to make them vibrate. By adding mass to the walls, more of the energy from the sound will be absorbed by the walls, and less energy will be available to transfer through the wall.
• Damping: If it is more difficult for the wall to vibrate in the first place (i.e., it doesn't respond as much to the sound waves), then less sound will be transmitted.

This information was summarized from a more in-depth article from the Soundproofing Company.

The Walls

The most important element of a soundproof room is the walls. In the world of soundproofing, there are many wall options and many trade-offs. We chose a solution that is simple and cheap.

The lower part of the walls are formed by the concrete foundation; the added mass of these walls help to reduce sound transmission.

We added soundproofing insulation to the interior walls. The materials and labor for the R-13 insulation was cheap, so we insulated all the interior walls in the house. This will help absorb sound traveling through the air cavities in the walls.


We looked at several wall damping solutions for the media room. A popular solution is Green Glue, a compound put between two layers of drywall to dampen sound. The material is cheap, but it does require a second layer of drywall and extra installation time. Because is is inexpensive and not difficult to install correctly, it is popular in do-it-yourself solutions.

A second option is QuietRock. This is an all-in-one damped panel that is installed in place of drywall. Installation is exactly the same as drywall, but the material costs are more expensive.

Another option was Resilient Channels. These are attached perpendicular to the studs, and drywall is attached only to the channels. This allows the drywall to flex a bit and dampen more of the sound. It also provides decoupling from the studs. The channels are cheap, and installation is not too much more complex than just drywall. Care needs to be taken to prevent the screws connecting the drywall to the channel from touching the studs (this would prevent the flexing and decoupling of the drywall).

We chose channels because of the price and because the installer is familiar with them. Sound isolation clips can be used with some kinds of channel and provide extra isolation, but they add material and labor expenses. We decided channels should be good enough for the level of soundproofing we want. If we want something more, adding Green Glue plus a second layer of drywall is a relatively straightforward addition that we could do later. It wouldn't require removal or remounting of the existing drywall; it is simply a second layer added on top of the existing drywall and channels.

The Details

Walls are the most important part of soundproofing the room, but the details are also important. The mass of a solid core door prevents sound from easily travelling through it. A gasket around the edge of the door provides a strong seal against the frame when closed, and less sound is able to travel through the gaps around the edge of the door.

We avoided can lights because those allow sound to travel through the ceiling. Surface-mount lights allow a solid layer of insulation in the ceiling and nearly unbroken drywall on channels.

The attachment points of the projector mount and screen can negate the advantage of the channels, if screwed into the studs through the drywall. The projector mount is mounted directly to blocks in the ceiling. The drywall will be installed around the mount and a bit of sealant will provide a flexible interface between the drywall and the mount. The screen should be able to attach directly to the drywall without going through to the studs. It is heavier than the projector but spread over a larger area.

Carpet is an easy flooring choice. It provides extra soundproofing, is comfortable, and provides better acoustics. A hard floor would reflect more sound.

Sound travels well through the reflective walls of vents, but fresh air is critical in a tightly-sealed room. We are using a supply and return to the HRV system to provide fresh air into the room and evacuate the stale air. The supply will be tucked into an open portion of the closet, while the return will be in an enclosed portion of the closet. The closet should help muffle the sound that makes it to the vents. They both go to the HRV, which we assume will not transfer too much sound into the other ducts attached to it. Bends in the ducts will also help absorb sound.

Overall, not a lot of changes were needed to provide extra sound isolation in the media room; we mainly had to spend time considering details. From that, we should get a reasonable level of soundproofing without too much extra cost.