The Sound That Gets Around

So you have a noisy neighbor, or maybe your son is now playing the drums, or Dad has a new stereo system. The sound doesn't bother them, but the noise is obviously nerve wracking for the rest of us. What can be done to soundproof?

While you can beef up a single wall, ceiling or floor with soundproofing materials, you have to keep in mind that sound doesn't only travel in a straight line. The fact that your noisy neighbor is upstairs doesn't mean that all of the noise is coming through the ceiling.

Let's suppose you were to install an imaginary ceiling with 4" of lead. We'd be pretty sure that no sound is making it through that. You might be surprised, however, that you still hear that neighbor, or those drums. So where is the noise coming from?

Sound will "flank" around a wall or ceiling. In the case of our lead ceiling, sound has vibrated the walls in the room above. Their walls are attached to your walls. So some of the sound from the floor upstairs is actually coming through your walls.

Other common soundproofing culprits that you can easily address are:

Ducts: Often times there are common air ducts between units, or rooms of a house. Consider adding a duct liner to absorb some of the noise in them.

Seals: There are times when sound can travel under a wall, because the sound sneaks under the drywall. Remove the base molding and seal the area where the floor meets the wall. Use a good latex caulk or acoustical sealant, and replace the molding. Consider the same for electrical outlets and light switches. With the power off, remove the outlet cover and seal the area where the drywall meets the electrical box.

Doors: Obviously there's a large gap under most doors. Consider adding a door "sweep" available at any hardware store.

Windows: Sound coming in from the outside many times is entering not through the window, but around the window. If you remove the molding (casing) around the window, you'll likely see a large gap there between the drywall and the window frame. Fill with caulk, not an expanding foam. Large gaps (common, unfortunately) may need to be filled with a combination of scrap drywall and caulk.

For serious sound isolation, you'll need to treat the wall or ceiling with specialized materials designed for the task. However, consider the sound that is flanking around that treated surface. In some instances, this will require that you treat more surfaces. If possible treat the obvious ceiling, floor or wall first, have a listen, then before you consider adding more to that surface, consider treating the adjacent surfaces. At that point, the adjacent surfaces may more likely be the culprit than that treated surface.

One last tip, treat the noise producing side for better soundproofing results. This will limit the amount of sound that can enter the building framing. Once the vibration is in the framing it can travel far, like your voice along a string between two juice cans.