With cars getting faster, there’s always the risk of more cabin noise as speeds increase. But what is happening is the opposite. New cars today are much quieter thanks to layers of sound-deadening material. This prevents structural vibrations, like shaking panels, wind and tyre noise entering through doors, and engine and transmission noise creeping in from floors and firewalls. Car makers have invested millions in bringing decibels to tolerable levels. And this is more evident in luxury cars that set the standard for everything else. 
While not all of us have a fortune to spend on Bentleys and Rolls-Royces, the next best thing is using car soundproofing material in areas creating vibrations, or noise. This can emanate in different car parts. Engine noise is more evident at speed, road and tyre noise get into the cabin via the chassis and suspension, and wind noise is created from turbulence around the vehicle body, often from parts like wheel fenders and side mirrors. Sound deadening targets these areas with a healthy dose of soundproofing materials, With more of the vehicle covered, the materials dampen and block unwanted sounds. 

How It’s Done 

Sound deadening is one way to soundproof your car. To deaden or remove unwanted vibrations that create noise, soundproofing materials are placed over vibrating metal parts. This reduces metal from rattling and resultant airborne soundwaves from transferring to other metal parts. In most cases, isolating vibrating car parts is done with a butyl rubber deadening mat. 
To further reduce noise and loudness, a sound dampener is used. This can be a foam acoustic layer or mass-loaded vinyl mats. Either material is used on top of the butyl rubber layer and effectively absorbs and blocks remnant sound waves. Car parts lined with car noise insulation products include firewalls, floor pans, wheel arches, quarter panels, doors, boots and roofs. 

A Better Look at the Materials Used 

Butyl rubber covers the first line of soundproofing. The material has a pressure-sensitive backing to stick easily and comply with uneven metal components, and a top aluminium foil layer to stop soundwaves from spreading to adjacent parts. The material is easy to install (just peel off the backing and start sticking), very thin (at 2mm) to fit even the highest spots, and easy to cut and shape to suit any area. Added benefits are water and heat resistance, so besides sound, you’re also dealing with moisture and heat in one simple product. The material is also odourless, won’t rot (unlike older-style bitumen-based deadener) and holds its own against tears or punctures. 
This can be enough for some vehicles, but remnant soundwaves are absorbed and blocked by adding mass to the butyl rubber. Acoustic foams do a great job of preventing sounds from spreading. These are multi-layer open and closed-cell foams. They too are simple to cut, easy to install, and have an adhesive backing, so stick well. Thicker 12mm variants will be more effective, but if space is an issue ultrathin 4mm foams are your best bet. 
Another alternative used in luxury vehicles is mass-loaded vinyl. This is a heavy-weight sound barrier that is also limp and flexible, easy to install and effective at blocking stubborn noises. The material doesn’t require adhesive as the weight is enough to keep it in place but is often combined with a thinner insulative foam for the best results.  

Benefits of Soundproofing 

Reducing noise levels with car soundproofing materials greatly improves your driving experience. The vast list of benefits includes: 

• Increased comfort – lower noise from rattling car parts or outside factors improves comfort and reduces driver and passenger stress and fatigue, especially in longer drivers or when off-roading. 
• Fewer distractions – focussing on the road ahead instead of distracting sounds in different car parts increases concentration, and significantly lowers the risk of accidents. 
• Better audio quality – hear every nuance in your favourite tracks, have buzz-free calls, or normal conversations without having to shout or turn up the volume. 
• Improved heat and water resistance – all of the sound-deadening products mentioned above also reduce cabin temperatures for safer, comfier rides, as well as water ingress, thereby preventing damage to electrical components or rusting. This has a direct impact on your car’s resale value. 

Can All Vehicles Be Soundproofed? 

Short answer, yes. The materials work best when applied in stages with butyl rubber first and foams and vinyl layers added later. A critical factor here is available space. Luxury cars, vans and 4WDs do better in this respect. But even older and smaller hatches and sedans can see a drastic reduction in decibels with layers covering areas that get the loudest. Even only covering the floor pans, door panels and firewalls in thinner butyl rubber leads to a much quieter interior. Adding soundproofing to roofs and boots or insulating engine bays and bonnets goes one step further. 
Car makers now take noise, vibrations and harshness (NVH) seriously, and subsequent models are not only more comfortable but also much quieter. Much of this is due to the ample use of deadening products, as well as more streamlined, aerodynamic designs, quieter tyres with lower rolling resistance, abundant use of seals, thicker glass, and parts like harmonic balancers to reduce engine noise. All these work together for a smoother, noise-free ride.