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What is Soundproofing Foam?

B. Turner
B. Turner

Soundproofing foam is a building material used to control the transmission and absorption of sound. This material can be used to achieve two distinct goals when it comes to sound control. First, it is used in homes and commercial buildings to block sound from the outdoors, keeping the interior of the space quieter for the occupants. Second, it can be used to absorb noises in recording studios or theaters, which reduces echo and improves the quality of the sounds.

To understand how different types of soundproofing foam can be used, one must first understand how sound waves and noise levels are measured. The ability of an object to block sound is measured by its Sound Transmission Coefficient (STC) rating, which can range from 0 to 100. A wall with a STC rating of 50, for example, means that noise levels on one side of the wall are 50 decibels higher than on the other side. Sound absorption is measured using the Noise Reduction Coefficient (NRC), which generally falls between 0 and 1. This number shows the amount of sound absorbed by an object, and the higher the NRC value, the more noise is absorbed.

Soundproof room.
Soundproof room.

When used to prevent noise from entering a building or home, soundproofing foam must be very dense and solid, causing sound to deflect off the material. A liquid variety of foam is often used in homes. This material is sprayed into the walls and expands to completely fill the space. While the soundproofing capabilities of this spray foam range by manufacturer, it offers a NRC of .7 and an STC rating around 37 on average.

Acoustic foam for soundproofing.
Acoustic foam for soundproofing.

Soundproofing foam panels are also used inside of building walls to help deflect sound. Made from polyurethane or polystyrene, these insulating panels generally have a STC rating between 20 and 50, depending on the thickness of the panels and on how many layers are used. When foam-core structural insulated panels are used in place of traditional framing and insulation, the wall may have a STC rating of 50 and a NRC of .95 on average.

Soundproofing foam panels are commonly used in recording studios.
Soundproofing foam panels are commonly used in recording studios.

In situations where sound must be controlled within a room, foam panels are used on the face of walls and ceilings. This is a common application in recording studios, gymnasiums, churches, and auditoriums. Open-cell foam panels allow some sound to enter the voids within the foam, where it is converted to heat energy and absorbed. This helps improve sound quality by minimizing echo and making the sound more clear to listeners. These soundproofing foam panels are made of melamine, and generally have an “egg-carton” or other deeply textured surface.

Discussion Comments

anon984784

I just spent $2,000 for this "soundproofing" foam in my apartment. It was just installed yesterday, took eight hours. I am devastated to say that it did absolutely nothing. I literally spent $2k just to have dust everywhere from them working. Guess I'm just not meant to sleep soundly.

anon241217

I've got three words for all you people: green glue sandwiches. No I'm not talking food here. Look it up. It's green glue between two slabs of drywall/sheetrock. If all you need is low-frequency sound blocking, then that's all you need.

If you need mid-high sound freq blocking, layer in some natural cotton fiber insulation and mass-loaded vinyl. There's your budget professional studio recipe right there folks.

Oh, and don't use wood. When it comes to soundproofing and sound transmission, metal studs, believe it or not, are the most effective in blocking sound, more so than vinyl, if they are tightly adjacent to other materials (such as drywall).

anon183843

Yep to everything everyone wrote so far. In one flat a friend owned, noisy partying people moved in below, slamming doors, music, etc. We put in permanent floating floor (that is, foam sheets, then 1/2 inch plasterboard on top, then interlocking chipped boards to walk on w/o breaking the plasterboards), then linoleum on top of the chipboard. Had to cover every inch of the flat. Otherwise, areas like the closet, if not done, would leak the noise. Cost about 3k and two weeks to do, but in the end, the noise now only coming through the walls and open chimney just a bit. Weeks later, my friend said, 'why didn't we do this years before?'

Now, in a rented flat with neighbors barking, screaming and carrying on, I made my own removable panels with 2x2 wood frames, plasterboard screwed on top, and cut bits of carpeting on top.

Friends come over and ask about the screaming neighbors they hear in the hall, but I can't hear them. Trust me: if I can build these four panels (materials cost about $275 - Wall area 15' x 8') anyone can build it, as I am truly atrocious with a saw and hammer. I filled in all the cracks with t-shirts, and everything from my closet.

anon128207

As an acoustician I am not aware of any spray foams that have been proven to increase sound isolation (sound proofing). Please enlighten me with manufacturers details and test data.

The only benefit of foam is when using the open cell variety (non sprayable) within a cavity where it will make a few dBs difference. Even this is most uncommon as foam is very expensive when compared to the superior glass and rock fiber products such as Rockwool and Owens Corning. Mass (bricks / blocks / drywall) is by far the most important consideration when attempting to increase sound isolation.

Your point about open cell foam being used to control sound reflections for better room acoustics is correct although often fabric face glass wool products are preferred due to their superior fire rating, range of colours and longevity.

With respect I would advise readers that this article is largely misleading and could result in a waste of money, effort and frankly heartbreaking results.

The best sound proofing material for dwellings bar-none is called Green Glue. I have no affiliation with the manufacturer (the huge multinational Saint Gobain) but I recommend you look at their website as it is filled with great factual and practical information backed up by lab test data.

anon124863

Are their renters apartment/condo laws concerning paper thin walls and floors/ceilings? I suffer every moment from this disturbance and also do not feel free to move about as I feel I am probably also disturbing others.

oasis11

Subway11- Sorry you have to go through that. I also live in a condo and wanted to add tile flooring. So my contractor used sound proof insulation when he installed my tile floors and I am so glad I did that.

I did not realize that sound proofing was such a big deal. I think my contractor used a product called Laticrete. It is supposed to be one of the best sound proofing materials on the market. It literally covers up any sound so that you walk around comfortably and not disturb anyone.

subway11

I just wanted to add that sound proofing material for floors is critical in an apartment building or condominium complex. I live in a sixteen story high rise in which most of the apartments come with Berber carpeting, however there are some owners that prefer wood floors.

According to our condo by-laws wood floors can be installed provided that sound proofing material is used. The owner’s one floor above me did not add the sound proofing material to their floors and we hear every step they take. It is really uncomfortable.

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    • Soundproof room.
      Soundproof room.
    • Acoustic foam for soundproofing.
      Acoustic foam for soundproofing.
    • Soundproofing foam panels are commonly used in recording studios.
      By: antbphotos
      Soundproofing foam panels are commonly used in recording studios.
    • Spray foam commonly used in houses for insulation has some soundproofing capabilities.
      By: auremar
      Spray foam commonly used in houses for insulation has some soundproofing capabilities.
    • Accoustic insulation can be used to soundproof a floor.
      By: Silvia Crisman
      Accoustic insulation can be used to soundproof a floor.