Automotive Sound Deadening Materials Guide: Discover the Power of Insulation
One of the main differences between current luxury cars and the second-hand hatchback you bought years ago is the level of noise that penetrates into the cabin. Comparing the two, even in the shortest trips to the shops, is like night and day. Noise, vibration and harshness, or commonly called NVH are just some of the metrics that set brands apart. Road, tyre and engine noise can become tiring to the point it’s a downright nuisance. Deadening out the decibels is what carmakers strive to better do from one model generation to the next. The abundant use of various auto noise insulation products and in the right places in the vehicle certainly helps here.
Noise levels vary with speed and different road surfaces. When the engine is idling and the vehicle at a standstill, there’s barely any audible sounds. At speed, however, you’ll hear the wind, the tyres, the transmission and engine droning, and any vehicles on the road. Driving on paved roads and dirt trials also makes a difference. Though most carmakers now take the time to reduce noise and improve cabin comfort and ride quality, older vehicles tend to struggle in this respect. If you’re rebuilding an older car, or have one still in use, there are ways that you can reduce noise to tolerable levels.
What is Sound Deadening?
Sound deadening in vehicles means reducing the sound entering the cabin. Car builders and manufacturers use a range of auto noise insulation products that dampen and absorb sounds emanating from different parts of the car. Body panels and chassis components are the main culprits here, since they resonate when vehicles gain speed. And sounds increase with speed. To deaden out uncomfortable levels entering the cabin, the car floor can be insulated with layers of different sound insulating products. The thicker the layers, the less sound and noise there will be.
Types of Sound Insulating Products
Older cars relied on layers of bitumen-based mats that were fitted below the carpet and the carpet underlay. Newer products however provide better insulation, and aren’t as thick, meaning several layers can fit in the same space. These are butyl rubber dampening sheets that are fused with an aluminium top layer for additional effectiveness. They are only 2mm thick, yet stick well to all types of sheet metals in the car floor. The combination not only reduces sound, but also heat from the exhaust, transmission and engine. In addition, butyl rubber is impermeable so doesn’t let in water or other liquids, and won’t rot or deteriorate when exposed to higher temperatures over time. This is the first layer of a multi-layer solution to sound insulation. Butyl rubber pieces are cut and shaped to fit the car contours. They are fitted to the floor, roof, firewall, along doors, the boot and inside cavities. You can continue with adding the carpet, or go with other products if there is space available.
To reduce noise levels even more, a second layer is added. This consists of mass vinyl that covers the entire floor pan from the front to the rear firewall. Mass vinyl comes in at 2mm and is coupled with a 6 to 8mm thick closed-cell foam layer. The combination is easily applied, and acts as a sound barrier to completely block out sound. It too is durable, water and heat resistant, so increases cabin comfort further. It has a non-stick surface, so is easily removed. If you see this as a permanent sound and heat solution, then adhesives can be used on the foam for a secure fit.
The three-layer auto noise insulation combo is what luxury car makers use in their high-end cars. They deaden noise, and also serve to reduce heat. Sound deadening packs are available for most vehicles. However, they’re best suited for utes, vans and 4WDs that see extensive use in conditions that generate a lot of noise. Vehicle-specific packs are available, so there’s minimal work in applying separate layers and no mismatching parts. If you’re rebuilding old classics, then noise insulation will provide you with less cabin noise and also more bearable temperatures.
Benefits of Sound Insulation
Buyers opting for auto noise insulation products are seeking a quieter, comfier ride. Even the butyl rubber layer used on its own lowers decibels significantly. But in combination with the mass vinyl and foam insulation, road, tyre and engine sound are brought to a minimum. All that is left is to add the carpet of your choice on top. A quieter cabin lets drivers and passengers talk without the need to shout, hear every note from the speakers, and reduce stress levels from high-pitched noise. In addition, sound layers reduce heat along the firewalls and car floor, particularly good for long, hot Aussie summers. And they act as barriers from any spills that can make their way into cabling or cause rust.
Installation and Buying
If you’re rebuilding an older car, you’ll already have it stripped down. Layers are easily applied and fit to the floor well. You can also choose to have the insulation professionally installed. Retailers that stock automotive sound insulation products also offer installation. Get a quote and look for kits that fit your car.