How to Soundproof a Room

When considering how to go about soundproofing  a room, whether commercial, industrial, or residential, there are several factors to address. First, investigating the source of the sound (if unknown) and determining the path of reverberation is essential in both sound minimization and in developing a soundproofing plan for the room. After addressing the source of the noise and minimizing it if possible, selecting an appropriate material with which to further minimize the noise and soundproof the room is typically advised.
 

How Sound Travels
 

If the source of the noise is an industrial machine, it is often very difficult to minimize the noise at its source. Instead, examining how sounds travels from its source to its final destination—the transmission path—is often the appropriate place to start. Sound travels in waves that can be slowed, reflected, or refracted by objects it encounters. Transmission paths can vary, depending on the sound. Sometimes sound moves directly from the source to the ear of a nearby receiver; other times it encounters barriers along the way that reflect some of the initial sound back, thus dampening and softening what the end receiver hears. Sound can also travel through the ground and surrounding structures, which further complicates tracing its route.
 

Addressing Noise 

In trying to reduce noise, it is often most cost-effective to attempt to treat the source of the sound itself before attempting to soundproof an entire enclosure. Examine the source of the sound (a drum set, a large industrial machine) and determine if any damping treatments can be applied to minimize the sound output. If possible, move the device in question to either alter the path of transmission or further reduce the output. Once the source of the noise has been addressed as much as possible, it may then be time to consider soundproofing materials for the larger enclosure. Common materials include the following:
 

• Acoustical Linings

• Absorbent Materials

• Barriers and Panels
  

Acoustical linings can be an effective method for lining electrical channels, ducts, and pipes, which are common ways sound is transmitted throughout (and beyond) a room. A lining with a thickness around 2 cm can be applied in ducts and vents to block high-frequency noise. Bafflers, another kind of duct lining, are another option for blocking sound in duct passageways.
 

Absorbent materials are often used to interrupt a sound’s transmission path by absorbing noise as it makes contact with the material. Instead of being bounced back, as it is when it makes contact with harder material, sound can be absorbed by softer, strategically placed material. Sound-deadening drapes and mats can be applied to ceilings and walls in already finished rooms; in unfinished rooms, the installation of fiberglass batting (and drywall board). The addition of fiberglass insulation, in both finished and unfinished rooms can greatly reduce the transmission of sound beyond the enclosure.
 

Barriers and panels are an effective way to reroute sound by interrupting the sound’s path.  When used in conjunction with absorbent materials, some of the sound waves will be absorbed (and dampened) while the remaining sound can be redirected. The manner in which a sound reacts to a barrier or panel can vary. A sound can follow one of several paths when it encounters an obstacle. Often, the sound passes through the barrier, although it is reduced in strength. Other times a sound can be reflected, meaning the path of the sound is altered and the sound bounces off the object in a different direction. A sound can also be diffracted, meaning the waves are bent and their path is altered. The best outcome occurs when the sound is completely absorbed by the barrier it encounters. Through strategic use of absorbent materials and barriers and panels, the path of the sound can be significantly altered and therefore reduced.
 

Basic Do-it-Yourself Methods
 

For those seeking to soundproof a room  on their own, there are several basic steps that can be taken. If the room has yet to be constructed but has all electrical wiring and piping in place, incorporating the steps below may help ensure a tighter, more soundproof enclosure. As always, a professional should be consulted before beginning.
 

1. Hang drywall over the existing walls, but leave enough space so that additional soundproofing material can be placed between the layers.

2. Apply fiberglass batting between the two layers, or cellulose-based foam. The goal is to apply a layer of batting that will further absorb noise.

3. Further soundproof the drywall by using prefabricated soundproofing material, such as rigid panels, barriers, or drapes, hang the material as directed. Next, re-hang the drywall

4. If the enclosure features windows, using a double-hung vinyl-framed window can help minimize the transmission of sound. If the windows are already constructed and replacing the windows is too costly, consider making covers for the windows out of prefabricated absorbent material, or hanging sound-absorbent drapes.