Sound Deadening

There is a reason this section is at the front of the line in our list. Put simply, it’s because of it’s importance in any system build and the effectiveness it has relative to the cost. Sound deadening comes in 4 different but equally important types: Speaker Baffles, Constrained Layer Dampers (CLD), Closed Cell Foam (CCF) and Mass Loaded Vinyl (MLV). Each is to complete a different job.

Speaker baffles are the first thing we would suggest in terms of creating a good environment for our speakers to work in. There is a few things these baffles do.

Firstly the silicone back shield provides a weather proof cover for the speaker which directs water around and away from the speaker basket.

Secondly the front of the baffle is designed to meet up to the door card, sealing against it. This stops energy from being lost up in the door cavity so all the energy fired from the speaker is directed through the speaker grill of the door card and into the cabin.

Third is the egg-shell style back wave absorption panel which adheres to the door behind the speaker and stops the rear wave reflecting back into the speaker and cancelling and affecting the output of the speakers.

Removing all these common problems by adding speaker baffles with your speaker installation drastically improves the output and overall sound quality of every aftermarket speaker upgrade gives you more midbass response and clearer sound that more accurately represents what the original artist intended.

CLD is the standard type of sound deadening material you see everywhere. The stuff worth talking about has two layers, a viscoelastic layer of butyl rubber, and a thin sheet of aluminum as a constraining layer. A CLD’s job is to lower structure-borne vibration of panels by converting mechanical energy (the vibration) into heat via the viscoelastic properties of butyl while the constraining layer helps the panel keep its shape and resist deformation.

The primary way that CLD achieves this is through shear forces in the butyl layer caused by being constrained between the panel and the constraining layer while the panel is vibrating (flexing). When the panel flexes, so does the CLD. When the viscoelastic layer stretches and deforms, it naturally resists and wants to “snap” back into place.

The next most crucial aspect in sound treatment for your vehicle is also pretty straightforward; a decoupler. We use open cell foam product for this job. The primary goal here is to provide a soft cushion between two panels using the natural compliance of the foam to prevent them from vibrating against each other, creating audible buzzes and other annoyances. The compliance and thickness of the foam is what is going to separate an ideal foam from a not so ideal foam in different situations. I prefer to use a foam that’s as thick as possible without compromising the integrity of the re-installation of the panels.

The final piece to the puzzle after you have lowered structure borne resonance and eliminated all of the panel-on-panel vibrations is to lower the outside noise entering your vehicle. This is what I refer to as soundproofing your vehicle. This is the most daunting and time-consuming task when sound treating a vehicle. There are two ways to eliminate sound from entering an area; blocking and absorption.

Blocking is going to be the most effective way for a car since blocking only needs mass with an air gap, while absorption needs a relatively thick open cell or fibrous material. You would need an absorbing material that is way too thick relative to the size of the car to do anything meaningful for road noise. That said, those types of products still have their place, but let’s focus on blocking noise right now. In order to block noise you need to have a decoupled mass.

The most popular choice for this in the aftermarket car audio world is Mass Loaded Vinyl, aka MLV. To be effective you need 100% coverage. No way around it and I’ll give you an example as to why. Have you ever had your neighbor start his lawnmower up early in the morning after a hot night with your window open? Annoying right? Well it doesn’t matter how closed your window is, even all the way until there’s only half a centimeter left. Only once it is completely closed and locked into place is the sound blocked and reduced to an acceptable level. Same applies here. This material is applied to the doors, inside the roof lining, on the floor pan, boot area. Everywhere or nowhere!