The 4 Most Soundproof Wood Options

With noise linked to serious health issues that include hearing loss and heart disease, soundproofing your home is more than just about comfort. And if wood is your preferred material, it can be tricky to choose the most soundproof type because of the overwhelming number of options and the alarming amount of false advertising in today’s market.

In a nutshell, the best soundproof wood types are Cork, Acoustic Plywood, Medium Density Fiberboard (MDF) and Oriented Strand Board (OSB).

The rest of this article will explain the basics of noise control, review the most soundproof wood types in great detail, and highlight the most important factors to consider when choosing wood for soundproofing. Read on for more.

The Basics of Noise Control

To understand how soundproofing works and how to effectively use wood for that purpose, you need to know the basics of noise control in a building.

Generally, there are two elements of noise control in a home setting:

Controlling the nature and quality of sound produced within your home
Blocking out unwanted sounds from external sources such as nearby traffic or a noisy neighbor.

Essentially, both tasks involve dampening echoes and preventing unwanted movement of sound waves from one point to another. Most commonly, two soundproofing techniques are used to achieve that.

These include:

Sound absorption
Sound blocking

Despite their differences, these two techniques are often confused, leading to many homeowners using materials designated for sound absorption for sound blocking and vice versa. Inevitably, this ends in disappointment.

To clear things up, let’s compare the two techniques:

Sound Absorption vs. Sound Blocking: What’s the Difference?

Sound absorption utilizes sound dampening materials to minimize echoing and reverberation within a room. Contrary to common belief, materials used for sound absorption don’t prevent sound from leaving/entering a room. Rather, they absorb it to reduce echoing, reverberation, and amplification.

Typically, the best materials for sound absorption are porous, with ample air spaces to enhance their effectiveness. That means sound can travel through them (even though it may come out with less energy on the other end) and is the main reason you shouldn’t use sound-absorbing materials alone to block noise.

Sound blocking, on the other hand, seeks to contain sound within a room and/or prevent noise from outside sources from entering a building. Materials used for this function are typically heavy, dense, and thick—with absolutely no air spaces.

Sound Absorption vs. Sound Blocking: Which Technique is Best for Soundproofing?

For complete noise isolation, you need a combination of both techniques.

You need sound-blocking materials to stop sound from traveling through your ceiling, walls, floor, windows, doors, and other openings in your home. This way, you can prevent sound from within your home from escaping and minimize disturbance from noisy surroundings.

At the same time, you need to employ their sound-absorbing counterparts to minimize the echoing and reverberation of noise from within and outside your home.

The 4 Most Soundproof Wood Types

In no particular order, here are the four most soundproof wood types:

1. Cork

Cork is certainly a wood type you’ll want to consider for your next soundproofing project if you want to get a bang for your buck. In addition to great acoustic properties, it’s natural, eco-friendly, and antimicrobial, making it a cost-effective option for soundproofing your floor against a noisy downstairs neighbor. And if the noisy neighbor lives next door or upstairs, you can use cork to soundproof your walls and ceiling, too!

If you’re familiar with wine, you’re probably thinking of the plug used to cover a wine bottle. Interestingly, the cork we’re talking about in this case is the same material used to make the wine bottle plug. It’s extracted from the cork oak tree, which primarily grows in the northwestern parts of Africa and the Iberian Peninsula.

But if cork comes from trees, how can it be eco-friendly?

Cork’s sustainability stems from the fact that the trees don’t need to be cut down to produce the material. Rather, the bark of the cork oak tree is stripped to make the product, and the trees continue thriving without it.

What Makes Cork a Good Soundproofing Material?

As mentioned earlier, complete soundproofing requires a combination of sound blocking and sound absorption.

In terms of sound blocking, cork isn’t necessarily the best option. Effective sound blocking requires a combination of great mass and density. When sound comes across any soundproofing material with these two characteristics, it bounces off, effectively stopping unwanted transmission.

Unfortunately, cork—and wood in general—is lightweight and relatively low on density.

The good news, however, is that cork is great at sound absorption. Generally, sound absorption requires porous materials with plenty of air spaces to trap sound. Thanks to the honeycomb-like cellular structure of cork oak, cork has plenty of such air spaces and is one of the reasons it’s often used for insulation and sealing.

To put things into perspective, let’s take a look at the latest sound test results, and compare the STC rating of 12mm APC cork to that of the Proflex RCU 250. When tested on 6” (152.4mm) slab, the APC cork gave an STC rating of 72. This is significantly higher than the STC rating of an 8-inch(203.2mm) slab of Proflex RCU, which is about 56.

So while it may not be great at blocking sound, cork’s great acoustic properties can help you effectively soundproof your home. In a nutshell, these include:

Sound absorption: due to its small cells, cork has lots of air spaces that help trap sound. In 1cm3 (0.0610237 in³), there are around 40 million cells. Such a high surface area to volume ratio increases porosity and enhances cork’s ability to trap and absorb sound—which stops transmission.
Noise reduction: Cork’s unique cell structure also helps it reduce sound vibrations. This comes in handy when you want to stop low-frequency sounds from traveling through walls or prevent the impact of your feet from disturbing the downstairs neighbor.
Acoustic Insulation: Cork’s great sound absorption capability excels at minimizing acoustic transmission through ceilings, floors, and walls. By absorbing mid to upper frequencies, it prevents echo and reverberation.

2. Acoustic Plywood

Similar to cork, acoustic plywood is great at sound absorption, but not so great at sound blocking because it’s low on density and mass. That said, this type of wood is great at sound control. It fragments standing sound waves, bounces high frequencies, absorbs bass sound energy, and generally improves sound quality in a room.

But to realize these benefits, acoustic plywood has to be perforated to let air pass through and subsequently dissipate sound waves. Typically, manufacturers use round, square, channeled or oblong perforations. Some mix things up to improve aesthetics and sound absorption effectiveness.

What Makes Plywood a Good Soundproofing Material?

To improve its density and weight, acoustic plywood is often combined with other materials such as Amorim cork rubber to form soundproof plywood panels. Doing this improves the sound blocking capability of plywood, and the result is a panel that can block and absorb sound.

Without other additives, acoustic plywood can still serve as a sound control material and is often used in home theatres and concert halls to reduce frequency acoustics and enhance sound clarity.

With regards to soundproofing at home, you can use acoustic plywood to:

Fragment standing sound waves caused by resonance within a room. Typically, resonance amplifies low-frequency sounds, which causes walls to vibrate. So by fragmenting standing sound waves, you can prevent amplification of low-frequency sounds—such as bass from music, for instance—within your room, thus effectively dampening noise.
Absorb bass from loud music. Plywood’s NRC rating is higher at low frequencies, meaning it’s more effective at absorbing bass and other low-frequency sounds.
Minimize impact vibrations on the ceiling of your downstairs neighbor when you walk around or move items. In addition to its great soundproofing qualities, non-sanded plywood makes a great material for sheathing floors because it’s cheaper and resists moisture better than many commonly used materials, including MDF.
Reduce echoes and sound reverberation. By dissipating sound waves, acoustic plywood prevents echoes and sound reverberation.

3. Medium Density Fiberboard (MDF)

MDF is a type of engineered wood made by fusing broken-down softwood or hardwood fibers with resin binder and wax under heat and pressure to create panels. Wood panels with this kind of construction are typically denser and stronger than other types of manufactured wood, such as particleboard and plywood.

In terms of soundproofing, few wood products come as close to drywall as MDF. That’s because it shares several important characteristics with drywall, most apparently the thickness, STC rating, and density. In fact, its 720 kg/m3-rated density is higher than the approximate density of drywall, which is about 650 kg/m3.

Despite its excellent acoustic qualities, MDF has its fair share of drawbacks as a soundproofing material. It’s highly flammable, absorbs moisture quickly, and hard to work with. It also releases VOCs when you cut it due to the adhesives used to hold the wood strands together.

On the bright side, MDF is very strong, making it a great option for soundproofing projects that require structural rigidity.

What Makes MDF Great at Soundproofing?

MDF’s excellent soundproofing capabilities are courtesy of its high density, thickness, and STC rating. With such characteristics, it can effectively contain all sound frequencies, something that many wood products struggle to achieve.

And since it’s made of wood, it can also absorb sound, making it one of the best types of soundproof wood if you’re looking for complete noise isolation.

4. Oriented Strand Board (OSB)

Like MDF, OSB is created by pressing various wood strands together and securing them in place using adhesives. That means like the MDF, OSB may emit VOCs when you cut it. However, it doesn’t absorb moisture as quickly as MDF. On the contrary, it’s very slow to absorb water, making it an ideal soundproofing material in areas where moisture may be a problem.

OSB is also cheaper, despite sharing similar soundproofing properties with MDF and drywall. So if you’re looking for a cheaper alternative to MDF or drywall, this may be it.

What Makes OSB a Good Soundproofing Material?

Thanks to its high density and mass, OSB can block sound to reduce its transmission from one room to another, especially when combined with other materials such as glass wool. But its ability to block sound is admirable; its sound absorption is what really stands out.

In one study, researchers tested three types of OSB wallboard for sound absorption and reverberation, and the results compared to those of concrete and brick. The findings showed that rooms insulated with OSB wallboards (made of OSB wood, glass wool, and air) were better at absorbing sound than brick and concrete buildings. This was particularly true for low-frequency sound.

Based on these findings and the fact that OSB has an impressive STC Rating, it’s safe to conclude that OSB wood can get the job done when it comes to soundproofing—especially when combined with other materials.

How to Choose the Most Soundproof Wood

Since different wood types provide varying degrees of soundproofing, it can be tricky to choose the best fit for your project.

To help you out, here are three important considerations you need to keep in mind when shopping for the most soundproof wood:

The Impact Insulation Class (IIC)

As you shop around for soundproof wood, you might come across a number that indicates the ICC rating for the product in question. This is a measure of how well a floor/ceiling can resist the transmission of impact or structure-borne noise. In simpler terms, it indicates how easily a particular type of wood will let sound vibration travel through your floor to your downstairs neighbor’s room.

At the very least, you’ll want a wood type with an IIC rating of 50. Not only will this minimize noise disturbances, but also ensure compliance with building code requirements.

The Noise Reduction Coefficient (NRC)

The NRC is the industry standard measure of how efficient a material is at absorbing sound, and ranges from 0.00 to 1.00.

An NRC of 0.00 indicates that the material in question doesn’t attenuate any sound, but rather reflects it. On the other hand, a soundproofing product with an NRC of 1 will absorb all the sound energy with absolutely no reflection.

So if you see a soundproofing material with an NRC rating of 0.75, for instance, it means it will absorb 75% of the sound and reflect 25% of all the sound energy it’s confronted with.

Since reflected sound creates echo and reverberation, a material with a higher NRC rating is always recommended. That’s especially true if you’re looking to construct a home studio. With a lower NRC rating, the sound would reflect off the walls, and the resultant crashing of sound waves would create a continuous sound cacophony that’d make it impossible to distinguish individual words.

For decent sound absorption, look for products with an NRC rating between 0.4 and 0.5.

The Sound Transmission Class (STC)

The STC rating is a measure of how well a partition in a building reduces airborne noise. In the US, this rating is widely used to evaluate the effectiveness of soundproofing materials used in windows, doors, ceilings, floors, exterior wall configurations, and interior wall partitions.

With regard to wood soundproofing, the STC reduction of any given wood type is a rough estimation of the net decibel noise reduction it will provide if you use it in a partition. It’s a rating you’ll want to pay attention to, especially if you’re looking to insulate a room against speech sounds.

For music, noise from machines, or any other sounds with a lower frequency than speech, you’ll be better off using another rating such as the NRC or IIC. That’s because the STC rating doesn’t accurately capture a material’s ability to reduce low-frequency airborne noise.

As is the case with NRC and IIC, the higher the STC rating, the more effective the wood type in question will be at reducing airborne noise. To attenuate loud speech, you’ll need something with a rating of about 40 to 50. But if you’re looking for complete noise isolation, you’ll want to go with an STC rating of 50 and above.

Summing Up

Noise control involves controlling the nature and quality of sound produced in a room and preventing unwanted sound transmission through a combination of sound absorption and sound blocking techniques.

Generally, wood is good at sound absorption because it’s porous, with plenty of air spaces to trap sound. However, it’s not so great at blocking sound because of the low density and mass. To address this, manufactured wood types such as Medium Density Fiberboard (MDF) are engineered with high density and mass while retaining the natural porosity of wood.

The most soundproof wood types are:

Cork
Acoustic plywood
Medium Density Fiberboard (MDF)
Oriented Strand Board (OSB)

To choose most soundproof wood, you need to consider the Impact Insulation Class (IIC), the Noise Reduction Coefficient (NRC), and the Sound Transmission Class (STC) ratings.