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!

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.

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.