Stop Noise in Its Tracks With Sound Blocking Material

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Road noise is a … frustrating part of driving, and some cars are worse than others. Whether you have an expensive audio system or are tired of having to yell while driving on the highway, investing in some quality sound blocking material will give you control over what you hear in your car cabin.

Mass loaded vinyl is a high quality noise abatement material that can substantially decrease the noise level in your car cabin, with the best results if installed correctly alongside effective sound deadening. It's possible to get a 95%+ reduction in sound pressure and roughly 2/3 reduction in the perceived volume you hear. Second Skin is here to help you get those type of results in YOUR vehicle.

Get to Know Noise Barriers
A good noise barrier will prevent sound waves from passing through it. Architectural Acoustics by David Egan summarizes the current building standards saying “The ideal sound isolating construction would be heavy, limp, and airtight.” The same materials and principles used to block sound in a home or apartment are used in a vehicle. Just like you'd want to avoid hearing your noisy neighbor through your walls, ceilings, and floors, Second Skin's sound blocking materials will wind noise and keep unwanted sound outside your car cabin.

As with anything else you buy for your vehicle, noise barriers come in a wide variety of material quality – ranging from incredible to ineffective (and even smelly). We want to make sure you understand the fundamentals of blocking sound waves so that you can make an informed decision about what’s right for you.

Want to Block Airborne Noise? You Need A Noise Barrier!

The manufacture of sound blocking materials is big business these days, and it’s not because of the automotive industry. Creating more comfortable and environmental living spaces has been a growing priority for the construction industry, and automotive companies are starting to wise up and apply those lessons to auto. For commercial and residential construction, the leading noise blocking materials are gypsum board (drywall) and mass loaded vinyl (MLV). Both gypsum and MLV have a comparable density per square foot, but mass loaded vinyl is the leading solution for vehicles because of its flexibility.

Remember earlier when I talked about sound deadening and sound blocking working together to reduce the noise level by 15 decibels? You don't? Well, that's why I said it again! Those unwanted sounds you hear inside your vehicle are traveling towards you along two very different paths. To get the best results, you have to match the product to the path you want to silence.

Structural Noise

Some sound waves travel through the vehicle’s structure before radiating into the passenger compartment. Vibration energy generated by mechanical systems and from road and tire friction moves through the metal chassis, floorboard panels and body structure of the vehicle before reradiating into the car cabin as noise. In many cases, the metal panels can even amplify the sound, like the buzzing noise when you turn the bass up on your audio system.

The solution to improve your acoustics is to apply car audio sound deadening material to any metal that vibrates. As the name implies, sound deadening materials dampen the metal and mute the vibrations, much like stopping a noisy wind chime with your hand.

Airborne Noise

Other types of unwanted noise travel into the vehicle by air. The air molecules surrounding the vehicle transmit unwanted sound from the exterior of the car, through the body panel, and then finally into the passenger compartment. These noises include the droning noise of exhaust system resonance, the roaring of road noise that comes from the tires, and even noise from air flowing under the vehicle.

The solution to airborne noise is to create a high quality sound barrier using the three key principles of blocking sound: heavy, limp, and airtight. The idea is to create a personal bubble that rejects airborne sound waves before they reach you.

If you use the wrong products for the application, use low-quality products, or apply products incorrectly, you will get inferior results. That’s why people get widely differing results when adding sound dampening material to their vehicles. Avoiding those expensive mistakes is easy – thank goodness you're reading up on it!

What Makes an Effective Noise Barrier?

To see how this works, let’s look at how a soundproof room is constructed. The same principles apply to soundproofing a room as soundproofing a vehicle. So, picture a recording studio – go ahead and put your favorite musician in there.

Musician's in there? Just checking. If you are like most people, you are picturing a room with walls that are covered with a thick foam padding. That soft foam is great for the acoustics of the room, but it is not a noise barrier. In fact, if there was a wall made only of that soft foam separating you from another person, you would be able to converse through it because sound easily penetrates open cell foam. Then why is the foam there? Because instead of blocking noise, the soft, lightweight foam is excellent at absorbing sound and quelling light echoes. That’s all it does. If that's what you're looking for, cool. We've got melamine foam sheets for you.

Then what prevents outside noise, like the sounds of street traffic or of the rock group next door, from entering the recording studio? It’s the construction of the wall: more specifically the effective combination of drywall, insulation, and mass loaded vinyl. A material’s sound isolation properties increase linearly with its mass. A denser material blocks sound better than a less dense material, per Egan’s Mass Law Curve in Architectural Acoustics.

chart of Egan's Mass Law Curve

Gypsum board can be anywhere from 1 to 3 lbs per sq ft depending on its thickness and the manufacturer. Typically, a 1/4” board of drywall is about 1.2 lbs per square foot and 5/8” of drywall is about 2.6 lbs per square foot with ½” drywall falling in the middle. Mass loaded vinyl is typically sold between 1 lb per square foot and 2 lbs per sq ft. Because the amount of sound blocked is linear relative to mass, thicker and denser material always means reduced noise.

To achieve the sound isolation required of a recording studio, you need a wall assembly consisting of multiple layers of gypsum board and mass loaded vinyl with batt insulation inside the stud cavities. You may even utilize a double stud system to further bulk up your wall. No matter the wall construction, your room won’t be soundproofed unless you also address the biggest weaknesses: the doors and windows. A typical door without seals has nearly a square foot of airspace around it, so soundproofing the door becomes a critical component.

Applying Home Soundproofing Techniques to Automotive

Let’s take these home soundproofing principles and apply them over to automotive. A good place to start is with the three key principles that create a successful noise barrier.

Dense: you need at least one pound per square foot to effectively repel sound waves (and the heavier the better). If you go much lower than that, the STC rating won’t be high enough to be worth the effort.

Limp: the barrier should be somewhat malleable and soft to absorb the energy of noise vibration and to prevent it from resonating

Unbroken: any gaps in the barrier are gaps that sound waves can travel through

 

Mass loaded vinyl is the preferred automotive solution instead of gypsum board. The term "MLV" comes from the way the vinyl material is manufactured. To increase the mass of the vinyl sheets, heavy metal particles are mixed in during the manufacturing process. That extra weight increases the density and creates an effective sound blocker. MLV is preferrable to gypsum board in cars for two reasons. First, it’s more “limp”, one of our 3 key qualifications. Second, it’s flexible. The curved, vibrating surfaces of a vehicle would be a terrible place to try and install drywall.

Second Skin’s mass loaded vinyl options range from 1 lb per sq ft to 1.25 lbs per sq ft. We don’t recommend going up to 2 lbs per sq ft because the material becomes less workable, making it challenging to fit around the contours of your car.

Additional Sound Blocking Information

  • Limp barriers work better than rigid ones

    The mass loaded vinyl barrier has to be somewhat limp, because the give prevents your barrier from vibrating. This is true whether you're installing the MLV inside the wall of a room in your house or under the carpet in your vehicle. Think about if you hit a sheet of lead (which used to to be the go-to blocking blocking material before we learned about the health concerns); it won’t reverberate and ring like a rigid sheet of tin or brass. It’s the same with mass loaded vinyl – the flexibility and limpness prevent the MLV from vibrating. Because the MLV material doesn’t vibrate, you don’t hear the ringing sound.

  • What should you look for in an MLV sound barrier?

    The first thing you should confirm is the quality of the mass loaded vinyl. Two key indicators of quality are the MLV's STC rating and whether or not the company will describe it as odorless.

    • The STC rating tells you how well the MLV blocks sound waves, the higher the better. The density of most MLVs is between 1 pound per sq ft to 2 pounds per sq ft. The industry standard is 1 lb, which is what we recommend for vehicles because the denser versions of MLV are not as workable around a vehicle's curves. Most people use the 1 lb density for homes as well. For this density, you're looking for an STC in the the 26 to 28 range.
    • Being odorless indicates the quality of the materials that compose the MLV. It's possible to cut costs by making the MLV out of cheap recycled goods, but you pay for that cheapness in odor and blocking power.
  • Watch out for MLV made from low quality recycled products

    Most MLV products are made from recycled goods. We are a fan of recycling, but it's important to make sure you're getting the best quality if its going into your living spaces. If you get the cheap-o MLV, some of the problems you can run into are:

    • Inconsistent thickness, which can reduce the mass per square foot and reduce the effectiveness of your MLV sound barrier
    • They can smell bad. Not in my car please!
    • Can be more brittle and less flexible. You don't want the product to rip just because you bent it a couple of times.
    • Sometimes its not even MLV! We've seen this occasionally with MLV material people buy in hardware stores.


    Just do your research before buying.

How to Install Luxury Liner Pro

You don’t have to use an adhesive if you’re using it on the floor, but we recommend one. Apply Luxury Liner Pro using the Second Skin Contact Spray Adhesive, another strong adhesive (like 3M 90), or a super strong double sided tape. Apply the adhesive to the top of your sound deadener and to the foam side of the Luxury Liner Pro. We do not recommend installing Luxury Liner Pro on the car roof or anywhere else it’ll be upside down – it’s heavy and may fall.

Remember the 3 rules we discussed earlier! When installing the mass loaded vinyl, it should be left somewhat limp to prevent the MLV from resonating as it blocks sound waves. It also should installed covering as close to 100% of the car’s floor as possible with the seams taped together to ensure you don’t have any gaps. By using high quality, dense MLV, and installing it as a limp, unbroken layer, you’ll create the most effective noise barrier possible for your vehicle.

We always recommend installing Luxury Liner Pro at the same time that you’re installing your Damplifier Pro sound deadener - save yourself the time and effort and do it all in one project.

Luxury Liner – an MLV Noise Barrier for Home Use and for Vehicles

Luxury Liner is our MLV without the fused layer of closed cell foam. Just like with Luxury Liner Pro, we’re very particular about the quality of the vinyl to ensure it’s odorless and the mass per square foot is consistent. Luxury Liner is most commonly used for sound isolation in two use cases involving home or commercial soundproofing projects.

The first use case is replacing a layer of drywall to beef up a wall’s STC rating. To create a soundproof wall, it’s very common to screw two layers of gypsum board together to increase density and sound isolation. Mass loaded vinyl can be used in place of one of these layers of drywall to get a higher STC rating at a lower total wall thickness. MLV is a denser material than gypsum board, so it blocks more sound per inch than gypsum board alone. Just staple the MLV airtight to the studs with holes cut into it for wall outlets and other openings. Then caulk all edges with a non-hardening compound. By using acoustical caulk that stays rubbery, when the caulk dries it won’t get brittle and chip away. You likely will also want to use foil tape to ensure the barrier is airtight. After installing the MLV, screw the gypsum board flat against it to complete your airtight barrier.

The second use case is for a partial wall that doesn’t go up above a dropped ceiling. If the wall stops at the ceiling tiles, noise can easily pass through the tiles and into neighboring rooms or offices. Install the mass loaded vinyl from the top of the wall to the true ceiling, extending the wall and blocking any noise that was passing over your partial wall. Mass loaded vinyl is by far the easiest and most effective solution for a partial wall with a dropped ceiling. Just like in the first use case, you’ll want to use acoustical caulk and tape seams to ensure an airtight barrier.

For Automotive: Don’t Skip The Decoupler

Remember we said that everybody who installs sound control products does not get the same results? We always recommend using a decoupler when installing Luxury Liner MLV in vehicles.

If you use Luxury Liner on top of Damplifier, or any other sound deadener, you need to install a soft, decoupling layer (such as our OverKill Pro closed cell foam or Heat Wave Pro jute insulation). The softer decoupling material prevents the two hard surfaces from resonating together. Don't allow the sound waves from that vibration energy to reduce your results.

 

Using MLV Around the House

Luxury Liner is an excellent solution for your typical wall, ceiling, or floor soundproofing projects. While it's best to install the MLV inside the wall attached to the studs, you can install it without taking down the sheetrock by screwing the mass loaded vinyl directly into the gypsum board. Just make sure it lies flat with no air pockets. Any trapped air will cause acoustical issues by causing the two layers of to resonate together, severely reducing any sound isolation effects. You can choose to leave the MLV exposed, or sheetrock over it as long as your third layer of drywall also lies flat with no air gaps.

Luxury Liner MLV can be used in home theater rooms, music rooms, or any other noisy room in your home. Did you buy your kid a drum set for Christmas? Want to create a soundproof booth? You’re looking for an MLV noise barrier.

Mass loaded vinyl can be used to wrap anything making noise, like metal HVAC ducts, a generator box, or plumbing pipes. If you have questions about your specific application, please give us a call.

Second Skin Is Here to Help!

Quality materials matter. Why go through all the effort of deconstructing your car or home only to be guaranteed subpar results due to inadequate materials? Do it right the first time.

Max out your car soundproofing project by installing a noise blocker on top of your sound deadener. Once you’ve upgraded to a personal bubble of calm, you’ll be glad you did.

If you still have questions, don’t go it alone! Call in for help on your project before you buy anything. We’re here to help.

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