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Car Sound Insulation and Sound Deadening Foam for Vehicle Acoustics

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Noise has been shown to decrease the quality of our living spaces and add stress to our lives. That’s why the residential soundproofing and acoustics market has exploded over the past few decades. As the market grew, more products were introduced to help control sound in residential, commercial, and industrial settings. Many of those same products have been adapted to play a similar role in vehicles.

Car sound insulation is a useful tool in your toolkit to create a more comfortable car environment. The sound absorbing and decoupling done by foam and other insulating products plays a key role in decibel reduction and improving vehicle acoustics, often making them a necessary supplement to sound deadening and sound blocking material.

We spend a lot of time in our vehicles, so it should be a comfortable space. Sound deadening foam and sound insulation will reduce interior noise and echoes to give you the best environment for your car audio and your day-to-day life.

Popular Vehicle Acoustics Materials

Avoid Mistakes. Know What Sound Absorbing Foam Will Do… And What It Won't

Don’t buy a piece of foam, attach it somewhere in your car, and expect your car to be any quieter. Foam will not “block” unwanted noise like automotive mass loaded vinyl. It also will not work as a vibration damper for metal like our butyl rubber mat or liquid sound deadener.

Foam will, however, absorb airborne sound waves. The frequency and total amount of sound absorbed depends on the foam.

Type Product Impact
Sound Deadening Damplifier Pro, Spectrum Sound Deadening Spray Stops noise from structural vibrations by deadening the metal
Sound Blocking Luxury Liner Pro Fused foam and MLV act as a heat and noise barrier
Sound Absorbing OverKill Pro Closed cell foam decouples hard surfaces
Sound Absorbing Mega Zorbe Open cell foam absorbs sound waves

Foam Products Absorb Airborne Noise

Think of foam as a sponge, but instead of absorbing water it absorbs noise. Unlike a hard metal surface which will reflect sound waves, the porous foam surface allows sound waves to penetrate it. Once inside, the wave reverberates around the interior of the foam until it runs out of energy or it exits. Even when sound waves exit prior to dissipating, they will have less energy than when they entered. The thicker the foam, the better it will be at absorbing noise, especially low frequency sound waves.

For vehicles, we prefer to use thinner cuts of our acoustic foam because space is limited and the flexibility and ease of fitting makes it more practical. For home or commercial sound proofing projects, foam is often chosen for for echo reduction because people don't know what else to buy. In most situations, you'll want to use acoustic fabric panels or other acoustic material options for increased durability and/or better aesthetics hanging on a wall.

What Makes a Good Sound Absorbing Foam?

If you’re looking to absorb sound, you’re looking for an open cell foam. Open cell foam excels at absorbing mid-to-high frequency sound waves and is used in everything from gymnasiums to churches improve sound quality, although for commercial and residential applications we'd usually recommend you go with acoustic panels.

There are a ton of foam products out there, but most of them are not much use in your vehicle. We’ll get back to that, but to understand how foams are evaluated – you need to be able to read a chart.

Chart

This chart shows you how effective the product is at absorbing different types of sound.

  • The y-axis ranges from 0 to 1 and shows the percentage of sound absorbed. 1 = 100% absorption
  • The x-axis shows a range of hertz, indicating the sound wave’s frequency. In the soundproofing industry, an STC rating measures effectiveness from a standard range of 125 Hz to 4000 Hz – so many tests cover those frequencies.
  • Each colored line represents a different thickness level at which the foam was tested. A thicker foam will absorb more sound.

Success on this chart means absorbing as much sound as possible, while keeping the foam as thin as possible. It’s an important measure of quality, but you need more than that to be good enough to put in a vehicle.

Sound Absorbing Foam in Vehicles: You Need 3 Things

For a foam to make the cut to go in a Second Skin vehicle, it needs to do three things:

  1. Designed for wear and tear
  2. Resist the elements
  3. Enhance sound quality

Our foam products go through rigorous testing to ensure they can take a beating. These foam panels aren’t going on a soundproof wall to spend the rest of their lives 30 feet in the air. You’re installing them in a modern miracle of design and technology that is constantly exposed to heat, wind and rain, while traveling at sometimes lethal speeds on all sorts of terrain. This foam needs to be able to take a punch. But what foam do you need?

Open Cell versus Closed Cell Foam

If you're comparing open cell versus closed cell foam, open cell foam is a less sturdy product and will absorb water, so it needs a hydrophobic treatment to prepare the foam for vehicle use. Do not put foam that isn't water resistant in your vehicle, especially not the door panels! The trapped moisture creates the potential to grow black mold, which can literally kill you. Closed cell foam is denser and more rigid. It’s not very good at absorbing most sound waves, although it will do a little bit to stop low frequency sounds, such as engine and road noise.

Product Type of Foam Touch & Feel Sound Absorbed Other Uses
Mega Zorbe Open Cell Foam Soft and flexible Mid-to-high frequency noise Class A fire rated thermal insulator
OverKill Closed Cell Foam Dense and rigid Minimal; some low frequency noise Decouples hard surfaces

Mega Zorbe

Our Mega Zorbe product is a ½” thick melamine foam that we’ve treated to be more durable and hydrophobic. It’s great for thermal insulation, absorbs an impressive amount of noise, and comes with the option to include an adhesive backing for easy application.

Overkill

Our OverKill line of products come in 1/8” and 3/8” thicknesses and are excellent decouplers. OverKill’s primary uses are to squeeze it between plastic panels to stop rattles and to combine it with a mass loaded vinyl (like Luxury Liner) to create a noise barrier on top of your sound deadening materials. We have customers who swear they’ve shaved a couple decibels just by shoving OverKill behind cupholders.

A common use for both Mega Zorbe and OverKill is to install it inside the door panel as an easy way to improve the acoustics of the door. Mega Zorbe is more effective, as it’ll absorb a lot of the back waves, but OverKill will help a bit too – similar to how putting a carpet in an empty room helps a bit with acoustics.

Second Skin Can Help!

If you’re looking for more help or advice on your project, give us a call. We’ll help you choose the right combination of products to get the best results. Put our years of experience to work and simplify your project!

Have questions about your project?

Call us at (800) 679-8511

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