Cars are manufactured with a lot of things in mind – materials, performance, cost, weight, to name just a few – but car audio tends to be an afterthought. 

Whether you're an everyday driver with too much road noise during your commute or a pro-audio enthiasist seeking the best sound quality, sound deadening car doors is vitally important.

Our decades of experience in professional car audio are poured out into this guide for you to transform your car doors into pro-audio doors.

Car Door Sound Deadening

The key to car door sound deadening is using a quality sound deadener on the metal in your car door. We recommend installing the deadener on the outer door skin and around your speaker to kill the vibrations. Follow as we go through the multiple different ways to approach adding sound deadener to your car door.

How to Sound Deaden a Car Door

1. Find out where the noise is coming from by adjusting the fade and balance settings on your audio system.
2. Tighten any loose screws to stop rattling. Try adding washers or closed cell foam to decouple.
3. Replace blown or broken speakers.
4. Install Speaker Tweakers to improve car audio by preventing speaker back waves from bouncing directly back into your door speakers.
5. Install sound deadening and soundproofing materials to your door. Read on to see what we recommend!

This shell is basically a cavern for noise with a crash bar in between. Seal around the bar with Damplifier™ Butyl Sealant Tape to control resonance. Next, cover the outer door skin with Damplifier Pro™ sound deadening. Similarly, the more quality car sound deadening material you add to your door, the quieter they get. A sound deadened car door means better audio quality, and we recommend covering as much of the metal as possible as this will have a big impact on the overall sound quality improvements you're seeking to make.

Research Tip

When buying deadening materials, pay close attention to what it’s made of. You don't want mass loaded mats and you don't want cheap fillers in your butyl or asphalt. Using a poor performing mat will drastically reduce your vibration damping (sometimes as little as 1/10 the effect). Not only do these products do a bad job of sound deadening, some versions smell bad, offgas, or come unstuck.

Next, combine Damplifier Pro with Mega Zorbe™ hydrophobic melamine foam (HMF) on the door's outer skin. This aircraft-grade thermal insulation and sound deadening foam is great for improving the sound quality of your door speakers by absorbing echoes inside the door cavity. This will help you get the acoustics right and increase what your ear perceives as the overall power of the system.

T-Fade from Everyday Audios Adding Sound Absorption to a Car Door

You may see a plastic “vapor shield” covering the inside of your car door, you can remove this to make it easy to access the inside of the door with sound dampening material. When you're done, you can add the vapor barrier back if it's in good shape. (Our butyl tape is the perfect adhesive for that.)

Use Damplifier Pro™ to deaden the vibrations of the inner sheet metal. A quick solution is to place Damplifier Pro™ over the area where the speaker hole is (covering it), and then using a utility blade to cut a hole for your speaker. By completely encasing your speaker with high-end sound deadener, you're attacking the root of your car audio problem as efficiently as possible.

Couple all this with Speaker Tweakers to keep the audio focused towards you and help stop speaker back waves from distorting the speakers in your car doors. We call this, "The Speaker Cradle" as Steve Meade's signature deadener move. You'll see it in a ton of his videos. Another option is to add speaker box insulation, which we wrote an article on if you're interested.

Depending on the strength of the vibrations, you'll also need add some Damplifier Pro to the remaining parts of the inner skin.

Steve Meade Cutting a Speaker Hole in Damplifier Pro

Install Luxury Liner Pro™ (LLP), the best automotive sound barrier material you'll find, over the access holes in the sheet metal to create a subwoofer box. It will increase its density and reduce outside noises from resonating through the metal and into the car's cabin.

You can take it one step further by sealing up the door cavity with Luxury Liner Pro™ to get even more out of your speakers while also making the vehicle quieter. In our testing, sealing the door is the best way to reduce noise from the door (also increases mid-bass). Combine this treatment with Mega Zorbe inside the door cavity for the best possible door soundproofing.

Check out how our friends over at CarAudioFabrication used a combination of Second Skin sound dampening materials to transform their car doors from echo chambers into beautiful speaker enclosures.

Mark from CarAudioFabrication Upgrading the Door Panel

Installation Tip

Use High Temp Spray Adhesive or Super Strong Double Sided Tape to apply these materials on top of your sound deadener. When installing LLP make sure you have at least 3/8" clearance between the inner sheet metal and your door panel and your window still has room to roll up and down.

If you're looking for maximum SPL, start with Damplifier Pro™ on the car door panel. While mostly used for constraining and dampening metal, Damplifier Pro™ will help keep plastic parts (especially those that overlap) from rattling as much in intense pressure builds.

If you've got rattling plastic panels, the answer is OverKill™ or OverKill Pro™ closed cell foam to decouple that rattling plastic. For aftermarket speakers, this is a must to keep your sound coming through clear and clean when you turn the music up. Our high density closed cell foam is a denser material that will improve car door insulation inside the door cavity while reducing some low frequency sounds like road noise and speaker distortion.

Use clear plastic or tape on your door and draw a template to cut your material to size. Be sure to mark mounting points and holes for mechanical parts.

Installation Tip

Use plastic panel popper tools to carefully disconnect the plastic clips when removing the door panel to avoid scratches.

Team Second Skin (Jeffrey & Sydnee) Installing OverKill Pro in a Car Door Panel

The Second Skin Car Audio Door Kit has everything you need to amp up your car audio and max out your stereo system. You'll be shocked at how loud your speakers sound and will be completely done with that annoying rattling in the background of your music. This combination of materials will get you the results you're looking for.

• Damplifier Pro is the highest performing sound deadener available today. You want your music sounding right, so apply this to the metal on your doors to guarantee you're done with rattles.
• The second protective layer depends on which kit you go with. OverKill Pro closed cell foam decouples rattling plastic and improves acoustics. Luxury Liner Pro will create a noise barrier between you and unwanted outside noise.
• Finish the job with a pair of Speaker Tweakers to break up speaker backwaves.
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