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Sound Deadening Material to Stop Unwanted Noise

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Sound deadening is the hidden secret behind the upholstery of any successful automotive soundproofing project. If you didn't already know that, you're in luck because you've stumbled into the right place. If you did know that and have a noise or heat issue, we look forward to helping you solve it.

We're here to help you find the best car insulation solution for your vehicle. Whether you have rattling metal distorting your speakers, a car restoration project, or want to create a bubble of comfort for yourself as you drive down the highway, we have the high quality products that will get you where you want to go.

We want you on Team Second Skin. In the article below, we'll walk through why cars make so much noise, the types of noise in vehciles, and our recommended solutions. We have deadening mats and liquid deadeners, all tested to give you the most possible soundproofing for your vehicle. Keep reading to learn more than you ever thought you'd know about making a vehicle quiet and comfortable, or reach out to us and one of our Second Skin soundproofing experts can help with your project. We're here to get you RESULTS!

Popular Sound Deadening Materials

Why Do Cars Make So Much Noise?

Noise inside the passenger compartment of a car comes from one of three sources:

  • Noise that enters through gaps, holes, and open windows.
  • Noise that is generated by automotive mechanical systems and travels through the vehicle structure before radiating into the passenger compartment.
  • Noise that is generated by automotive systems or an external source and enters the passenger compartment by first traveling through air, then passing through a body panel, and finally reradiating into the passenger compartment.

The first type of noise – sounds that enter through holes, gaps, and windows – is what most people think of as wind noise. Noise reduction for wind noise is fairly simple… fill the holes. Solving for the other two types of car noise is more complicated, but we'll teach you how to reduce road noise in your car as a fun diy project!

The science behind car sound deadening is the same as other parts of the vehicle. A sound damping material acts to the metal body panels the same way a shock absorber does to automotive suspension. As the wheel goes up and down over bumps, the shock absorber resists movement in both directions by pushing a piston through oil. This resistance reduces the amplitude of the travel of the chassis by a small amount each time, eventually coming to rest. A sound dampening material does the same thing, just in a different way. By resisting the minute stretches required for the metal to move in and out like a drum head, the amplitude is reduced, reducing the sound radiated into the car cabin.

Second Skin Audio has a complete line of automotive sound insulation, with multiple options for sound deadener, noise blocking, and noise absorption materials. Not only do we have all the high quality materials you need to completely insulate your car, we'll walk you through every step of the way!

Our Most Popular Product: Damplifier Pro Sound Deadening Mats

Two things matter for quality sound deadening (1) the quality of rubber and (2) the thickness of the materials. Our most popular product is the Damplifier Pro™ sound deadening mat – and it excels at both.

  • The self-adhesive mats are simple to install. Just cut, peel and stick. Controlling sheet metal vibrations is the first step to improving automotive sound quality.
  • We only use high-quality butyl rubber and thick annealed foil. We do not use cheap asphalt or fillers, and we don't skimp on the foil's thickness.
  • Butyl rubber is safe for use inside your vehicle. It's tough, won't melt, and won't out gas chemicals when it's hot.
  • Damplifier Pro was engineered for high performance, scoring between very good and outrageously good on industry standard vibration testing. It also has good thermal insulation properties to help keep your vehicle comfortable.
Damplifier Pro photo

Second Skin vs The Sound Deadening Competition

Second Skin demolishes the competition!! We could just say that (like some do), but that's not really helpful to anyone who's actually doing research. "Not helpful" is not our style. We get that you have options and want to be sure you're making the right decision. Instead, we've done our best to summarize how we think about automotive sound deadening for you. Hopefully it's helpful!

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The Two Types of Unwanted Noise: Structural & Airborne

Structural Noise

Structural noises originate from the exhaust, tires, and other external noise sources before entering the vehicle and transmitting through body panels and other metal components. You hear these car noises as vibrations, buzzing noises, roaring, droning, humming, rattles, squeaks, and groans. It's particularly bad in older and antique cars, and of course, any vehicle that has a killer audio system.

It gets worse. The metal body panels will actually amplify your car's structural noises. That's why you hear those aggravating buzzing noises with the audio system's deep bass sound. That's also one of the reasons your car is much louder on the highway – which is often when people notice the worst road noise. Highway road noise can be so loud that you can't hear the person in the passenger seat. Soundproofing your car will solve these problems.

The best way to reduce structural noise is by applying damping materials to the vehicle's body panels. A damping material is a resilient material that constrains the motion of the panel. "Loudness" correlates to the sound waves' amplitude, so by reducing the amplitude, we reduce the noise level. The less a car's body panel can flex, the softer the sound will be that it radiates. If you'd like to take a detour here and learn more about dampening vs damping vs deadening, feel free. We'll wait on you.

Airborne Noise

Airborne noises are sound waves that travel into the car through the air and then bounce back and forth inside the car's cabin. The best ways to soundproof unwanted noise traveling through the air is to block or absorb it. You either want the airborne sound waves to never reach you or, once they're in the car, to reduce the time they spend reverberating. Then you get to enjoy the quiet, calm environment you've created.

Think of a recording studio. The studio's walls, ceiling, and floor keep unwanted sound out by being dense and airtight. We then install sound absorbing materials on the walls to absorb the echo and reverb of the airborne noise inside the space. The result is greater control over the music that is heard and recorded. Soundproofing a car uses the same principles.

Sound will still be transmitting through the body even if you did an excellent job damping the metal and dampening that structural noise. Blocking the airborne noise that does make it through is absolutely key and requires mass. In a building, that mass is typically added using gypsum board, concrete, and wood. For automotive sound barriers, mass loaded vinyl with a soft decoupling layer (Luxury Liner Pro) is the best option to achieve high mass with good flexibility and a limited thickness. You MUST block airborne sound if you want a quiet vehicle.

Once airborne sound waves are inside the car cabin, the best you can do is to absorb them. The OEM insulation and upholstery in your car do most of the work here, although specific parts of the car like inside the door panels and above the headliner benefit from sound absorbing material. To add extra absorption to a your vehicle’s cabin, two high quality options are hydrophobic melamine foam and jute insulation.

Car graphic

Quality Sound Deadening Material Makes a Difference Don't Be Fooled.

The best products combine a butyl rubber, elastomeric compound with a thick, high-quality foil. They also don't use "filler" material, that's cheap but hurts performance. Think about it this way. Using filler is like stuffing your meatballs full of rice to make them bigger. Sure, you've got bigger meatballs. But they don't taste as good, because there's a lot of rice in there and it's not as FLAVORFUL. More filler makes the mat less rubbery and less elastomeric, so it won't snap back into shape like it's supposed to.

When we manufacture our Damplifier™ and Damplifier Pro™ self-adhesive sheets, we cut out all the fillers. Who wants a product that looks thick if it performs worse? Not us. We also don't use cheap, flimsy foil. Yes... that would save us money, but it won't constrain the butyl adhesive as well to stop those vibrations. Again, you've got an inferior product. That attention to detail is why our product specs are so much better than competing products.

The worst quality sound deadening material you can buy is made from asphalt roofing material. (No... just no.) Yes, asphalt will deaden metal a little bit so you'll see SOME impact. Somewhere between 10% and 30% the effectiveness of Damplifier Pro™. And maybe that sounds ok to you, because you're willing to sacrifice performance to save some money. The reason we avoid asphalt entirely in automotive is because we don't mess around with the health concerns. We are especially concerned about using cheap sound deadening materials around heat producing components or in a warmer climate, because asphalt will melt and out gas chemicals at high temperatures. Avoid the sticky mess and the fumes. Keep asphalt on your roof or on the road, not inside your car.

How do I know if a sound deadener has asphalt? None of them mention asphalt anywhere! (Wonder why that is…) That's the hardest thing about automotive sound deadening for your average DIY researcher. It can be hard to tell what's INSIDE the various mats. If you've read down to here in an article about automotive sound deadening, you care about improving the sound quality of your ride. Fortunately, there are some easy tells you can look for:

  • Anything sold by the roll is likely to be repurposed roofing material like what you can get at the local hardware store. It probably contains asphalt, and it definitely doesn't have a solid foil constraint layer. You can't roll up good foil like that.
  • Look for the temperature rating. Asphalt melts at a lower temperature than rubber, so as you start seeing a lower temperature range – the sound deadening material has cheaper fillers in it at best, but probably contains asphalt.
  • Buy made in the USA. While we've found USA-made products with a high filler content, we have yet to see one with an asphalt base. The imported sound deadening mats tend to be much cheaper per sqft, and much more likely to use asphalt.

So there you go – one of the sound deadening industry's dirty little secrets. Use the information how you will.

Damplifier Pro™ and Damplifier™ have been the sound deadener of choice for car audio enthusiasts for over 20 years. When you upgrade a stereo system, the sound energy being put out is upgraded beyond what the car’s original engineers intended. Unless you want vibrating metal to be part of the background noise, you can’t skip the deadener and you can’t use cheap “placebo effect” deadeners that you hope will solve the problem.

Don’t take it from us though. Just ask Steve Meade, EXOcontralto, or your neighbor Carl about how they all use Second Skin for their car audio builds. That fancy new stereo system is just begging you to fix the stereo sound with some Damplifier Pro. Try it out, and future you will be grateful.

And if you're looking for an alternate sound deadening product to our mats, try a sound deadening spray like Spectrum™ or the thicker Spectrum Sludge™. Both are water-based viscoelastic materials specifically formulated by Second Skin for high performance and easy workability. Yes, they work well. They're also easy to clean up with soap and water, environmentally friendly, and non-toxic. You just apply them differently. Spectrum™ is easy to spray, brush, or roll on. You can use it in place of our Damplifier products or in addition to them, because they can go places where it's hard to apply a sound deadening mat, like your vehicle's undercarriage or for wheel well soundproofing.

Mats or liquid

Mats or liquid? Which sound deadening method is best?

These can be used together. Many people do just that. The sound deadening mats are great for flat areas, making it an excellent choice for the firewall, floor, roof, or trunk. Mats can follow curves well too, if you trim them to fit, which is what most customers do for their door panels.

Sound deadening liquids are great for those hard to reach places, like a sound deadening undercoat, inside the fenders, and inside the wheel wells. We think both products look great – Damplifier has black mats with a ghosted Second Skin logo whereas Spectrum has a dark grey, seamless look once it dries.

You can apply Spectrum inside the car too. The product is really easy to spray or brush on once you've exposed the metal. It typically just comes down to your preference. Spraying Spectrum™ really shines if you have a large area to treat, like the inside of a van, the back of a Jeep, or a truck bed. Be sure to use our PlastiWrap™ and Wire Tape™ to mask off anything you don't want to be sprayed. Don't want to spray or don't have the equipment? No problem. Spectrum™ and Spectrum Sludge™ are easy to apply with a brush or roller. The Sludge can even by applied by hand.

Sound Deadening Material FAQ

  • How to Install Sound Deadening Material in a Vehicle

    Installing a sound deadener in a vehicle is pretty simple. Remove upholstery and paneling to expose the bare metal. Clean the metal. Apply the deadener. You should always roll a sound deadening mat on with a hand roller to ensure there’s a strong bond between the damping mat and the metal. If you don’t have excellent contact and adhesion, you will substantially reduce how well the deadening mat performs. To learn more about how to install sound deadening material in a car, take a look at our self-adhesive sound deadening mat install guide in The Owner's Manual resource center. You can also read about the technical specifications of our sound deadening mats by reading up on Damplifier Pro.

  • How Many Square Feet of Material Do I Need to Deaden My Car

    The answer to this question depends on the type of vehicle you have and which product you are using. With Damplifier Pro, we recommend 60% coverage of anything metal - so the doors, floor, firewall, trunk, roof, and hood. You can always go up to 100% coverage to max out performance and to help stop thermal transfer. For Spectrum, we recommend 100% coverage in 1mm layers – 2 layers for interior applications and 3 layers for exterior applications.

    So that's it:

    1. What’s the square footage of my vehicle? If you’re unsure about your specific vehicle, and don’t want to measure it – check out our nifty Square Foot Guide.
    2. What parts of the vehicle do I want to deaden?
    3. Do I want to cover 60% or 100% of the metal?

    Or you can ask us to do it for you with one of our Custom Vehicle Plans.

  • How Much Does it Cost to Sound Deaden a Vehicle

    Good question. There is no easy answer here. There are several factors to consider:

    1. How big is your car? A bigger car costs more.
    2. How much noise do you want to reduce? If you want to max our your soundproofing, it costs a lot more than stopping a rattling trunk or improving the acoustics of a door.

    If you just want to do a small deadening project, you can spend $50-100. For serious noise reduction, we’re talking $500 for a small car and at least $1000 for a large SUV. We wrote a whole article on car soundproofing cost if you want to learn more.

  • Does Sound Deadening Really Work?

    Yes, sound deadening a car will make it quieter. There are two types of noise in a vehicle: structural and airborne. A vibration damper will stop the structural noise by reducing vibrations, which you then hear as reduced vehicle noise.

    We wrote an answer to the does sound deadening really work. Check it out!

  • How Thick Should Sound Deadening Be?

    Sound deadening should be at least 40mil (1mm) thick, with most mainstream brands capping out at 80mil (2mm) thick. Besides total thickness, the other key variables are the formula of the butyl (elastomeric vs fillers) and the quality of the foil (rigid vs flimsy). It’s hard to tell the difference between sound deadeners without holding them, but like most things in life… you get what you pay for.

    Second Skin offers sound deadening mats that are 1mm and 2mm thick (Damplifier and Damplifier Pro), and a liquid sound deadener (Spectrum) that can be applied up to 5mm thick.

 

Use Second Skin™ Sound Deadening Materials to Soundproof Your Home

Any metal that makes too much noise can be soundproofed with the sound control methods you just read about. A few common examples we hear about are:

  • Generator boxes, RV generators, or any place a generator is stored. Deaden the metal around the generator enclosure to kill the vibration noise. If you use deadener on the inside of the enclosure, just be sure that it's 2 inches away from generator heat sources.
  • Computer tower walls. It kills the vibration noise that resonates through the metal.
  • Screen doors. Apply a couple of small cut outs to stop the cymbal like noise.
  • Kitchen sinks. Even luxury sinks can be loud. Learn how to quiet a metal sink and cut the noise level in your kitchen.

Damplifier Pro and Spectrum have been used around the home to soundproof dishwasher enclosures, tame unruly washing machines, or to quiet HVAC ducting. Commercially our vibration dampers have been used in too many ways to count, ranging from coin counting machines to hospital and warehouse carts. If the metal rattles, a little of our high quality sound insulation material will deaden it.

Second Skin Can Help!

Each project is different. Let us apply our years of experience to help you find the right product for the job. We’re happy to talk through any project with anyone who calls in. We've seen thousands of jobs – let us save you some time. Second Skin is here to help!

Any vehicle that rattles or shakes, and most do, can benefit from sound deadening. Whether you installed a high-end sound system, are fixing up a hot rod, or just want to carve out a little bubble of comfort for your drive to work, Second Skin's sound deadening are best in class. Join Team Second Skin and turn any car into a luxury vehicle!

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