Best Sound Deadening For Your Car

Want to prime your car’s cabin for some speaker upgrades? Treat it to the best sound deadening material that the aftermarket has to offer.

Have you ever stepped inside a luxury car and noticed how quiet it was when you shut the door? We are way more sensitive to sound than we realize. And as a result, that decibel attenuation is an expensive commodity. In true luxury barges, we even see double glazed windows with an air gap between them for that very reason. Bentley and Rolls Royce cars are said to offer ‘Splendid Isolation’, meaning in reality about 20dB of sound reduction.

The truth is, decibels of sound are slippery customers, moving about through air and metal and bouncing around inside spaces. Which is why we talk about two kinds of things to do with sound in any space, not just vehicles:

One is sound ‘proofing’ – or stopping the transference of sound, the other is sound ‘treatment’ – or improving the space’s acoustics. The upside-down mushrooms hanging from the Albert Hall’s ceiling were devised in the 70s, generations after it was built. It was an awful venue for sound and the shapes cured it. Likewise, your car has weird and horrible acoustics. Your cabin boosts bass, every surface else sucks up the high frequencies, while the windows make ugly reflections. That’s why there is so much interest in tuning car audio equipment to work well.

However, the best investment in the realm of automotive audio has to be the mods which make the cabin a better place for audio. And that is where sound deadening comes in. So, before you think about upgrading your car speakers or subs, give a thought to the products and brands listed below…

Best Sound Deadening Materials

Silent Coat

Made in the EU, this is a solid value for money product. Silent Coat has a wide range of matting at often remarkably keen prices versus some other brands. They have twelve products if you count the different thicknesses. The first are the foil and polymeric damping bitumen based sound deadening mats: Silent Coat in 2mm, Silent Coat Black in 3mm with black foil, and Silent Coat Extra in a fat 4mm thickness. There’s also Silent Coat Multilayer mat (which is used for heavy vibration areas) with foil atop butyl mastic with a mass loaded vinyl layer, then another of butyl.

Meanwhile, Silent Coat Isolator mat is a foam that can be had in either 6mm or a fat 10mm spec and is used as a layer on top of the deadening mat. That’s the sort of stuff you want when dampening high end audio or bass cars. You want your cabin to be inert, and still be able to afford the audio to install in it? This is a good option.

Specialized products

On top of all that, Silent Coat sells a 20mm or 30mm bonnet liner with foil topping, called Noise Buffler. It is fire retardant and heat resistant but no thermal rating is quoted. Then, there’s a polyurethane foam with an egg-box looking surface called Silent Coat Absorber, offered in 7mm, 15mm and a massive 35mm. This is all about high frequency sound absorption – it is said to absorb 30-40% more sound through its architecture. A major application for this would be inside bass boxes to stop resonances.

Lastly, Silent Coat Noise Isolator in 10mm or 6mm is a lighter weight closed structure cell foam used for doors and in the roof lining. It’s good for absorbing airborne noise.

As well as the mats, Silent Coat offer three kits. One is a basic hatchback deadener, and the others are for Land Rover Defender 90SWB and 110LWB.

Overall, Silent Coat provides cost effective stuff, and offers a good choice of products for different applications.

• Summer 2023 price of single sheet of Bitumen matting with foil backing: $3.10 / £2.40
• Try out price/product: 20x 2mm sheet Silent Coat, $62.68 / £47.99
• Number of kinds of products (as in varieties, not SKUs): 12, plus accessories and three kits
• Main Market: DIY audio customers, Land Rover fans

Noico

Available solely through Amazon, this is a factory selling directly to the public, hence the low prices. They only sell a limited range of just the key products; basically two things in a couple of thicknesses. The sound deadening mat is 2mm thick, and has a foil topping that Noico says is used as install indicator. If you have pressed the embossing flat during installation, you have squidged it firmly enough onto the surface of choice. They offer a roller to do this with and there is a black foil version available. You would use this where you might otherwise spot a silvery glimpse of bodywork on stripped-down but deadened cars. A black foil product is a common option in the competition, hence their copying it.

The other product is Noico Red. A polyethylene foam mat in either 4mm or 8mm. Used as a thermal insulator, it’s claimed to perform as well as rubber based foams. Another benefit is that is doesn’t give off any smell like polyurethane foam tends to.

Rated to 190F or 88C, Noico Red works well as thermal insulation for warm climate vehicles, although it is not rated to be used in really hot spots like say, Dynamat Hoodliner. A real commodity purchase, you buy this if you have a clue what you are doing and just want the basic sound deadening. Not really a wide choice of products for van converters, but it’s keenly priced and appears to be good stuff.

• Summer 2023 price of single sheet of Bitumen matting with foil backing: $3.50 / £2.70
• Try out price/product: ten sheets of black 2mm, $35.25 / £26.99
• Number of kinds of products (as in varieties, not SKUs): five
• Main Market: Audio customers mostly, direct from factory to customer, hence so low in price

Dodo Mat

With more products, more kits, and more bits to help fit the stuff, Dodo Mat are the DIY van converters’ favorite. With some crazy thick insulation for thermal purposes – even including a vehicle-safe lagging wool made from recycled bottles, you could build a sub-zero arctic weatherproof off-grid monster starting with this stuff.

Dodo technically offers 21 products, since many come in multiple thicknesses. Dodo DEADN Hex is their synthetic butyl foil faced deadening mat. It’s soft and flexible for easy installation and 1.8mm thick. DEADN PRO Black has black foil and has 2mm of that low odor synthetic butyl. Dodo SQ DEADENING PLUS is a foam layer atop the butyl. Next in line, DEADN DUO combines a deadening mat with a thermal insulator and the PRO version is 7mm thick as against 5mm.

Specialized products

SQ LINER is a closed-cell wavy-surface foam used for interior sound absorption, while SUPER LINER is a smooth faced foam. Used over a layer of deadening mat, you pick the thickness. It comes in 5mm, 6mm, 10mm and 12mm. The Dodo BARRIER mat, meanwhile, is a Mass Loaded Vinyl or MLV and is weighty at 5Kg/M². You would use that for sound proofing, as in blocking unwanted noise, say in your van walls. The PRO version has a layer of closed cell foam already laminated to it. SOUND STOPPER measures 14mm thick and is the ultimate carpet underlay, with a layer of MLV between two foam layers. It needs adhesive to fit, unlike all the other products, which are sticky-backed.

Finally Dodo THERMOLINER and the PRO versions (featuring a glass fiber reinforced aluminum layer) are sound and heat insulation mats. In version 3, the self-adhesive glue has been upgraded and the release paper is harder to tear. You can purchase it in 6mm, 10mm, 12mm and a thick 30mm form. The one like loft lagging, called Dodo THERMO FLEECE, is 50mm thick.

In short, Dodo Mat has absolutely everything you could possibly want from a sound deadening supplier.

• Summer 2023 price of single sheet of synthetic Bitumen matting with foil backing: $3.91 / £2.99
• Try out price/product: Single Sheet Dodomat, $3.91 / £2.99
• Number of kinds of products (as in varieties, not SKUs): 21, plus accessories and eight kits
• Main Market: DIY camper van conversions and audio customers

Skinz

There aren’t many kinds of products in the Skinz line up as this is all about hifi, and not camping. They are designed and made for the folks who also sell the Audison Thesis stuff. True audiophiles, they sell very high end electronics. As a result, two items in the range exist just to improve loudspeaker locations, as well as sound deadening products.

Skinz Expert sound deadening mat is available in 2mm or as Pro in the 3mm thickness. The Pro version has black foil, while the Skinz Panel Liner product comes in 6mm and 10mm. The latter is a foam layer and like others, is recommended for use on top of sound deadening mat. The Skinz Wave Diffuser is a wavy foam product intended to be fitted behind loudspeakers in doors. The idea is that it absorbs the back wave of the driver and avoids reflections or distortions from them. The other speaker based product is the unique Skinz WaterGuard, a soft silicone rubber boot in 165mm and 200mm sizes, which prevents water getting at speakers.

Another product others don’t seem to have is a dust and grease cleaner. A preparation spray, it’s used to make sure the self-adhesive layer on the deadening mat does its thing.

Sold through the FOUR Masters network of dealers, you will find Skinz products sold with Hertz and Audison kit.

• Summer 2023 price of single sheet of Bitumen matting with foil backing: $5.60 / £4.29
• Try out price/product: 3mm Door Kit of seven sheets of Skinz sound deadening is $39.17 / £29.99
• Number of kinds of products (as in varieties, not SKUs): six
• Main Market: High end audio customers

Stinger Roadkill

This brand is available at Halfords, as well as being widely distributed by AAMP Global’s UK/EU arm. Or, if you want to make life really simple, you can find Stinger Roadkill products on Amazon too.

It’s got pretty packaging and while a big brand, has a less than comprehensive set of products on offer. The coolest product it offers has to be the foam speaker installation rings. Made to hide inside factory speaker locations with aftermarket speakers fitted, they come in six sizes. They fit fives and sixes and three kinds of ovals, including 6x9s.They help reduce the factory locations’ stock ‘boxy’ sound. If you have a better install, they also offer an egg box foam pad to place behind speakers so as to dampen that back wave.

The product range

Stinger Roadkill Expert Lightweight is a foil-topped sound deadening mat sold in various size pre-packs, including 80ft² rolls. Overkill is a ¼ inch foam damping mat used for interior damping and is aimed at high frequency noises. The sole purpose of this one is to give you a quieter cabin. ULTIMATE combines a layer of Expert aluminum/butyl, with a layer of Overkill acoustic foam, in the one mat. They also do a Hood Liner with the aluminum layer and the heat and sound insulating foam. It’s rated to 255F or 124C – not as high as the Dynamat hoodliner (more on that, next) but that will be a more expensive buy.

Last is the Stinger Carpet Pad pack. Designed for the footwell, it has two layers, One of a high density semi-closed-cell foam and one weighty butyl/vinyl layer.

Stinger has a good selection of stuff and if you do run out, you can just pop out and buy some more at an actual shop.

• Summer 2023 price of single sheet of Bitumen matting with foil backing: $9.80 / £7.50
• Try out price/product: Speaker kit of two sheets of Black aluminium foiled, 2mm, $19.58 / £14.99
• Number of kinds of products (as in varieties, not SKUs): eight, plus branded glue
• Main Market: Audio customers online or available from Halfords

Dynamat

The daddy brand, created in the USA over thirty years ago, this is the stuff that folks brag about using. Car audio was their plot, although they also provide home audio application products. I saw Dynamat being used on the production line of the McLaren F1 – they’re THAT good. It is the best in terms of weight versus absorption at soaking up vibration, changing it to low level heat. Yes, when shouted at, sound deadening mat gets microscopically warmer! You cannot destroy energy, only dissipate it. And Dynamat is awfully good at it.

The product range

Sold as seven lines of products and some supporting bits like branded gloves, roller applicators and tape, the main stuff is Dynamat Xtreme; a bitumen based deadening mat with an aluminum foil topping. That stuff is sold by the sheet. Then, with blue rather than silvery foil, there’s Dynamat Superlite, which is 30% lighter and thinner, yet works just as well. Next, you can add a layer of Dynaliner. In ⅛, ¼ or ½ inch thicknesses, it is a lightweight heat and sound blocker layer. Dynacore, in half and one inch thicknesses, is a seriously meatier sound and heat absorber with a black fiber core. It is rated to 350F or 177C, so is useful for hot spots.

Dynamat Hoodliner has a 1mm foil layer and is made to reflect engine heat. Dynapad is a different three-core absorber mat, used for under-carpet heat and sound insulation. Lastly, Dynadeck, a vinyl thermo-acoustic foam mat made as a replacement carpet material.

• Summer 2023 price of single sheet of Bitumen matting with foil backing: £8.38
• Try out price/product: Door Kit of two sheets of Dynamat Xtreme sound deadening is £16.75
• Number of kinds of products (as in varieties, not SKUs) seven plus accessories like rollers
• Main Market: High end audio customers, supercars like McLaren.