I often get asked about the benefits of cork vs. foam for soundproofing, as both are cost-effective materials to buy in bulk. After doing some research, I’ve come up with a quick answer:
When it comes to cork vs. foam for soundproofing, cork wins every time. Cork is a sound deadener, meaning it reduces vibrational energy. Foam is a sound absorber, and so helps to reduce echo. This means cork has more effective soundproofing properties, while foam is acoustic management.In this article I’ll go into a bit more detail about the different products, and what each one does specifically. Hopefully by the end you’ll have a better understand of what to use where.
How Do Cork and Foam Work in Soundproofing?
Before getting into the specifics of what each product does, it’s worth covering what they actually are.
Cork is a naturally produced material that’s made from tree bark. It’s literally the same stuff they use to cork wine bottles. Importantly, it’s amazingly lightweight and a good insulator.
Foam is quite a general term in the soundproofing world, but it typically applies to acoustic foam panels. These are the things you see on the wall in recording studios and can be shaped like egg boxes or peaks and valleys.
Acoustic foam panels are designed to absorb sound. This is different from actual soundproofing, which is usually defined as blocking sound from entering and leaving a space.
In a way, sound absorption is part of the wider soundproofing picture, but on its own doesn’t block sound.
It’s measured by the amount of energy lost by a sound wave as it passes through a given material, in this case, foam.
The energy is converted from mechanical energy (vibration) into heat energy. The sound waves try to vibrate the particles in the material and lose energy as a result.
Acoustic foam is quite good at this because it has an open-celled structure. This makes it easy for sound waves to enter the material, but the number of tiny surfaces makes it expend a greater amount of energy.
To an extent, cork also absorbs sound. But it also works as a sound deadener. Deadening is the process of causing a sound wave to dissipate against a surface before it can pass through.
Cork is good for this because its structure allows it to compress rather than vibrate as a rigid material would. This makes it much harder for sound waves to transmit through the material.
In short, both cork and foam do different things. On their own, cork would be more effective, but if you want a properly soundproofed space then you’ll need to use a range of materials.
Comparison of Cork vs. Foam
So the important thing to note is that cork and foam do different things. One is a sound deadener while the other is a sound absorber. Absorption is more about reducing echo and so technically isn’t soundproofing. Instead, it’s acoustic management.
But in the end, you might need some of each to get the most out of your efforts. To help you decide which is right for the job, here’s a comparison chart of cork vs. foam.
|Purpose||Sound deadening / sound absorber||Sound absorber|
|Most effective frequencies||High||High – mid-range|
|Effective against||Impact and airborne noises||Airborne noises|
Perhaps one of the most important points to discuss in this chart is NRC. This stands for noise reduction coefficient, and is the amount of noise a material absorbs.
For example, acoustic foam as an NRC of 0.8, which means it absorbs 80% of sound that passes through it. In turn, this also means it reflects 20% of sound energy.
Of course, this is 10% higher than cork’s NRC. But this figure isn’t everything. As I’ve mentioned, cork also deadens sound, meaning it helps to dissipate sound waves along with absorbing them. In my opinion, this makes it a superior product.
It’s also worth mentioning the frequencies against which each product is most effective. Foam is most effective at high and mid-range frequencies while cork is most effective at high frequencies alone.
This doesn’t mean they don’t absorb other frequencies; this is just where they’re most effective. Both products are let down by low frequencies, but many soundproofing products are.
However, this is where foam pulls out in front. You can buy bass traps (Amazon link) that are designed specifically for lower frequencies.
Bass traps are a slightly denser foam and are produced differently. They’re ideal for trapping and absorbing frequencies that most other products are unable to manage.
Pros and Cons of Cork for Soundproofing
Each product has its own pros and cons when it comes to soundproofing. They’re only comparable to an extent, but knowing the differences definitely helps to make a decision.
Here are the pros and cons of cork for soundproofing.
- Natural and sustainable.
- Comes in different thicknesses and densities.
- Great as flooring and for use on walls and ceilings.
- Absorbs and deadens sound waves.
- 3mm of cork can reduce noise by up to 10dB.
- Also a good thermal insulator.
- Naturally fire retardant.
- Not great against low frequencies.
- Not a specific soundproofing product – it can be difficult to find the right thing.
Pros and Cons of Foam for Soundproofing
Foam, on the other hand, is a dedicated soundproofing material. Generally, it performs well at its intended job, but here are the main pros and cons.
- Ideal for reducing echo and reverberation.
- Comes in different thicknesses for different uses.
- Widely used in soundproofing – plenty of available info.
- Can drastically improve the acoustics in a space.
- Fire retardant.
- Doesn’t help to block sound.
- Let down by low frequencies – easily managed with bass traps.
When to Use Cork vs. Foam in Soundproofing
Because cork and foam serve different purposes in a soundproofing project, it’s worth knowing the specific applications of each product.
So here’s a quick guide on the best applications for cork vs. foam.
Cork can be used in its base form as either floor or ceiling tiles. You’ll find these quite easily online and in DIY stores.
But it also works as floor underlayment. This is ideal for reducing impact noises and can be covered with carpet if you don’t like the look.
You could also cover walls with cork tiles or sheets. Considering you have a wide range of densities and thicknesses to choose from, cork is quite a versatile product.
Importantly, you’d use cork in the earlier stages of your soundproofing project when adding mass and other materials to the walls, floor, and ceiling.
Cork can be hidden away behind drywall or under carpet and still offer some great noise reduction properties.
Acoustic foam tiles will need to go on the top surface of a wall with nothing obstructing them from the sound waves.
In order for them to be effective, sound waves must make direct contact with the foam’s surface.
Therefore, acoustic foam tiles will basically be the last step in your soundproofing project. You’ll only fix them to the wall once you’ve finished adding mass and whatever else you need to do.
Importantly, too, not every soundproofing project will benefit from acoustic foam panels. You’ll generally find them more useful if you’re building:
- Recording studio
- Home theater
- Jam room
- Games room
This is simply because acoustic foam doesn’t block sound or prevent it from escaping a space.
Acoustic foam reduces echo and reverberation to make sounds sound better. The result is greater clarity when you need it, rather than less noise entering or exiting a space.
So Which is Better, Cork or Foam?
When it comes down to the all-important question of which is better, there isn’t really a clear answer.
As you’ve probably already guessed, it depends on the job at hand.
Cork is better in terms of actual soundproofing because it helps to deaden sound as well as absorbing them.
Foam excels when it comes to absorbing sounds alone, and its versatility allows you to tackle different frequencies and vastly improve the acoustics of a space.
In short, if you want to prevent sounds from escaping or entering, choose cork as a cost-effective and natural alternative to other products.
If you want to reduce echo at all frequencies in a space, choose acoustic foam.
Some Final Thoughts
Hopefully, this article has given you some useful tips on the topic of cork vs. foam for soundproofing.
The best advice I can give is to think carefully about what you actually need from the product. This is particularly important here because they do similar jobs but with important differences.
Whichever you choose, be sure to use some other soundproofing materials to get the most out of your efforts.