If you are having noise problems and the noise source is outside your home, soundproofing could be a great solution. Constant traffic noise from a nearby road, loud neighbors watching tv or playing music, or even just walking around if they live upstairs, can be a real pain, especially if you are in need of good sleep. Or if you have family members who revel in loud activities — playing a musical instrument, watching movies in a home theater, woodworking — soundproofing can be used to imprison the noise and hinder it from disturbing the rest of the household.

If you've ever seriously considered moving because of a severe noise problem, soundproofing your home is definitely an alternative to have in mind. You probably won't need to soundproof your whole house; if you focus on the room(s) with the most prominent noise problem, you can create a noise haven. If you wanted to do some remodeling, this would be the perfect opportunity to implement soundproofing — it's always less demanding to build it into the construction than to add it later.

The basic principles of soundproofing

Sound absorption is not equal to sound blocking! Absorption one of the soundproofing elements, but it actually has a tiny contribution. Most materials with sound-absorbing characteristics are designed to improve the acoustics of a room, not to prevent sound from coming in or going out. They reduce echoing of already present sounds but they do not stop sound from entering or leaving the room. So a product having excellent sound absorption is not always useful for soundproofing. If you are in need of effective soundproofing, don't spend your time looking at products that are intended for acoustical room treatment.

1. Mass

You can block sound with any thick or heavy object. Drywall and mass-loaded vinyl are examples of decent soundproofing materials that use this charateristic. This approach is most useful against airborne sounds, like voices, and not so effective for impact noises such as footsteps, which are generally transmitted through the building structure.

2. Damping

Hit a wine glass with a fork, and it will ring. Now grip it with your fingers, and the sound stops instantly— that's the effect of damping. In soundproofing, damping is achieved with viscoelastic adhesive damping compounds such as Green Glue Noiseproofing Compound. The unique charasteristic of the damping compound is that it converts sound energy into heat, so that the sound abruptly stops, as with the damped wine glass.

For the damping composite to work, it needs to be placed between two stiff panels (drywall, plywood, or subflooring), which are then screwed together, creating a Constrained Layer Damping system. When the system is hit by the sound, it causes shearing forces between the stiff panels which create friction in the damping layer, hence converting the sound energy into heat.

Damping is the most capable of the four elements against low-frequency noise, like booming bass beats of music or noise from construction machinery.

3. Decoupling

Some sound is transferred through the building structure. Decoupling gaps are introduced into parts of the building, stopping the sound vibration from moving forward along its path.

It’s best to use decoupling during a building's construction, for example, by staggering stud beams so that the two wall panels are reinforced by two separate sets of studs, rather than having both walls use the same studs and hence being linked by them. Decoupling can also be included later, with resilient sound clips and furring channels, although the original structure (walls, floor, ceiling) needs to be removed first. Decoupling is also used with windows with non-parallel panes so that they don't vibrate simultaneously. Finally, decoupling is a critical element in the construction of a "room within a room," an innovative soundproofing method that is greatly effective.

Decoupling is used less than the other three methods, simply because it requires tearing out existing structure. Also, it must be done with extra precision, because if done poorly, it can create a resonance chamber, increasing low-frequency noise.

4. Absorption

Absorption has the least effect of the aforementioned elements. Acoustic ceiling tile and loosely packed fiberglass insulation are examples of decent sound absorbers, and they provide a little additional soundproofing.

These four elements work independently of each other. For example, this means that if you've already applied plenty of mass but no damping, you can gain considerable upgrade by adding a damping element to your soundproofing. So if you have already had certain soundproofing installed but it's not managing to reduce the noise good enough, think about which of the four element(s) are frail or insufficient in your system, and that's what you want to check in order to gain the most improvement.

Misinformation About Soundproofing

Be wary of ineffective “soundproof” construction material like:

• Soundproof paint: Guaranteed to deaden sound or absorb mid-range sound transmissions, soundproof paint is only good for covering faded spots or nail holes. At only 30 thousandths of an inch thick, this paint won’t diminish noise at the low and high ends of the sound spectrum, making it incompetent for most soundproofing purposes.
• Soundproof wallpaper: Like soundproof paint, most soundproof wallpaper is extremely thin and doesn’t live up to its promise of properly reducing noise. Many soundproof wallpaper products are simply normal wallpaper reinforced with a minimal layer of foam or other noise deadening products. It does not diminish high and low-frequency sound waves, failing to soundproof a room.
• Foam rubber: Yoga mat or mousepad rubber will not soundproof walls. Only particular noise-reducing materials containing foam, rubber, and other sound absorption factors will give you the type of wall soundproofing needed to properly control soundwaves.
• Carpet on the wall: Unless you’re purposely going for the eclectic or “shabby chic” look, tacking carpet on walls doesn’t effectively stop sound waves. The carpet may lessen some reverberation but does not have the needed density to diminish sound transfer.