If you’re into car audio, you’ve probably heard of sound deadening. But what is it, and is it worth doing?
Sound deadening is important, and it’s a straightforward modification that can make your car infinitely more livable for you and the passengers. Even if a vehicle has factory sound deadening, adding a few extra layers in critical places is worth adding to make your older ride feel more like a luxury car.
As an Amazon Associate, ImproveCarAudio will receive a small commission from qualifying purchases made through the links in this article.
Tip: Sound deading is an excellent solution for audiophiles because even the best and most expensive audio system will not play well in a loud car.
The first step is to sound deaden the car to eliminate any road noise so you can hear your music better.
In simple terms, a well-soundproofed cabin allows you to enjoy every single tone, make quiet phone calls or have a conversation without shouting over each other.
In this article, I will look at what sound deadening is, how it can improve your car’s audio, and whether or not it’s worth the effort.
Why Is Sound Deadening Good for a Car?
Sound deadening is the process of reducing the amount of noise that comes from your vehicle. You can accomplish this in several ways, but the most common is adding material to your car’s interior that will absorb sound waves.
This can make a big difference in the overall sound quality of your car’s audio system because even the best sound system will not play well in the metal acoustic box, and it can also make your car a lot more comfortable to drive in.
There are a few different things to consider when deciding whether to sound deaden your car.
#1. The first is the type of car you have.
If you have a newer car, it’s likely that it already has some sound deadening material.
However, if you have an older car, it is likely little or no sound deadening material installed. This means that you’ll notice a bigger difference after adding some.
#2. The second thing to consider is the type of music you like to listen to.
For example, if you listen to classical music or Jazz, you will notice less difference after the sound deadens your car.
But if you’re into heavier, bass-heavy music, you’ll want to add some sound deadening layers. Otherwise, all that bass will bounce around inside your car from one metal surface to another, making awful sounds.
#3. The third thing to consider is how much you’re willing to spend.
You can buy sound deadening material in various forms, from spray-on insulation to peel-and-stick mats.
The type you choose depends on your budget and the amount of time you’re willing to spend installing it.
So, is it worth it to sound deaden your car? If you’re looking for a way to improve the overall sound quality of your car audio system, then the answer is definitely yes.
Sound deadening is an integral part of any car audio setup, and it’s something that you should consider if you’re serious about getting the best possible sound.
Where Is the Noise Inside the Cabin Coming From?
The noise level inside the car primarily depends on the driving speed.
#1. When driving slowly in the city at around 30mph, most of the noise we hear comes from the engine.
#2. At speeds between 30mph and 50mph, the most audible are tires rolling on the tarmac
#3. Above 50mph and during monotonous driving on the highway, a lot of noise is caused by airflow around the car.
In the case of tires, cheap all-season and winter tires make most of the noise because of their material composition. Unfortunately, in many cars, the quality of factory-fitted tires could be better, and they do not offer either comfortable driving or low noise.
Thus, we often replace factory tires with better quality aftermarket tires that make much less noise inside the car.
Engines are also troublemakers. Although most modern engines are quiet, they do not stay brand new forever, and with a car’s age and increased mileage, they get louder.
Components inside the engines, like shafts or bearings, wear out and become loose. It also does not help when we skip regular services or oil changes.
Also, door seals that wear and become harder over time cause excessive noise from the airflow around the car’s shape.
There are ways to soften the door and window seals, and by doing so regularly, we not only increase their lifetime but also make them to better form against the metal door and, in effect, we keep the wind out of the cabin.
To all these noises that our cars make, we have to add sounds that we would rather not listen to with pleasure, like the other car engines, especially those with damaged or tuned exhaust, bikes, music all around, etc.
People usually do not realize how all these noises affect our nervous system (article opens in a new window).
Exterior noise at a busy street can cross 100 dBA, while the safe noise level for human ears is 85 dBA (an article about various noise levels opens in the new window).
It is a sizeable difference in the noise between various car types.
For example, while luxury cars create below 60 dBA inside the cabin, in small sports cars, we can experience over 70 dBA because of less sound-deadening materials installed due to the weight reduction, or less resistant mufflers to increase performance, etc.
One can tell it is just 10 dBA, so not that much. Well, not exactly.
In reality, 70dBA is over three times louder than 60dBA because the sound is measured on the logarithmic scale, which means that with every 3 dBA increase, the noise becomes twice as loud.
What Is Sound Deadening?
Sound deadening is the application of materials to critical areas in a car to absorb and dissipate noise. It is also commonly referred to as noise reduction, anti-noise, or damping.
By absorbing or dissipating vibrations, you will reduce the overall noise level in the cabin. This is because absorbing the noise stops it from being able to bounce around and echo off hard surfaces, which is what amplifies sound.
There are not many more annoying sounds we can hear than rattling or squicking the door right after installing brand new speakers.
We should not save on sound deadening the car when we spend thousands of dollars on quality car audio, including powerful door speakers and amplifiers. Especially soundproofing doors should be part of every car’s audio improvement.
You can listen to music in a soundproof car, like inside the acoustic studio. In other words, you can start hearing how speakers perform, and the difference is enormous. You do not hear any more resonance from plastic panels, distortion, or interior vibrations.
Even average quality soundproofing materials can make a noticeable difference.
Therefore, it is recommended to simultaneously add sound-deadening mats and foams to the door when you replace the speakers.
I could not believe it when I listened to the music the first time after I made from doors proper enclosures thanks to butyl mats and foams. After that, sounds became much more dynamic and precise. The difference was especially noticeable in the mid-bass.
To imagine the difference, try to listen to the music from the speaker lying on the table and then take the same speaker and install it into the enclosure. The similar effect you will see in the car before and after sound deadening.
Although there are more cars on the roads with completely soundproofed interior surfaces, the most critical areas for the music quality are the doors or side interior panels in the back of the two-door vehicles.
In general, every piece of a car interior to which we connect speakers should be covered with sound deadening panels and foams.
Even if you have a tight budget and want to avoid soundproofing the entire car, adding mats to the door will provide you with a much better acoustic experience than mounting speakers in a raw sheet metal enclosure.
The final effect will be much better than adding an amplifier to the same speakers but without sound deadening the door.
Why Is It Worth to Sound Deaden the Car?
Although the sound deadening car interior will improve the music experience, there are other reasons why you should add rubber panels to our cars.
Each year, more drivers decide to soundproof their cars, and they are not all audiophiles. And this is not only for the used cars, with old engines that are louder. More and more new vehicles are being soundproofed because of their mediocre factory insulation.
Sound deadening can be skipped when you drive Rolls Royce or Bentley, but unfortunately, I am not one of those drivers.
In addition to the sound reduction after soundproofing, the car interior is not heating up as much when it is hot outside.
This is due to insulation layers that prevent heat from entering the cabin, primarily through the roof and doors.
Every person has reasons for driving soundproofing decisions, but sound deadening generally increases driving comfort.
In my case, I love silence while driving. Driving a car for me is pure relaxation. So I often listen to my favorite Jazz filling the entire interior from 11 speakers around but not too loud. It is just perfect, exactly as I want it to be.
This level of silence was only possible to achieve with soundproofing when I had to hear all of the wind noises mixed with high tones.
What to Sound Deaden in Car?
Every car has a different construction and different interior acoustic or wind noise.
There are different factory insulation areas; therefore, we need to think about the best way to sound deaden the car, but that is a car-specific decision.
Nevertheless, there are common areas in all cars that can be better or worse taken care of, so below is my list of the places that may need attention in any vehicle:
This is the most popular starting point for many car owners when they decide to sound deaden their cars.
As I mentioned earlier, the door is a place where we install speakers, so it is essential to make sure that the sound is not leaking out of the door and that the sound waves can move freely inside the door panel.
Looking at the door from the inside, you will notice ample space. It is like an empty metal box. This is where most of the noise comes from when we are driving. Installing butyl rubber mats or foams in this area is crucial to improve the acoustic in the car.
The door is where we can achieve the most significant noise reduction in the car.
But before adding any materials to the door, we need to ensure that the door is properly sealed. All gaps and holes should be closed tightly so that no outside noise can enter the car.
Another area where car owners decide to sound deaden their cars is the floor. Just like with the doors, the floor is a large metal area with only a few places slightly covered with factory insulation.
This does not protect us from the noise that is coming from outside, wheels, and also from the engine compartment.
The easiest way to sound deaden the floor is to use a butyl rubber mat or thick foam. The mats are available in different thicknesses, so you can choose the one that best fits your needs.
The thicker the mat, the more sound will be absorbed, but it is also more expensive and can make the car heavier.
Some car owners use spray-on insulation, but there are better solutions. In addition, the spray is hard to apply evenly on the floor and can create a mess.
Sprays are excellent in tight hard-to-reach areas, but on the large floor, they are less effective than butyl rubber mats or foams.
The headliner is another area where we can improve the acoustic in our car. Just like with the doors and floors, the headliner is a large metal area not covered with any insulation.
The easiest way to sound deaden the headliner is to use a butyl rubber mat or foam. Adding butyl rubber mats or foams to the headliner will improve the car’s acoustic and make the ride more comfortable.
Also, it will reduce heating in the summer, so if you want to have cooler air in the car, take advantage of this area.
#4. Rear side panels
We hear most of the rear wheel noises on the rear side panels.
This is because those areas rarely have factory-installed sound absorbing materials, but after adding the panels, the effect is astonishing. I could not believe it the first time I tried it.
You will be surprised how much better the car will sound after adding butyl rubber mats or foams to the rear side panels. The ride will be more comfortable, and you will hear much less tire noise.
#5. Trunk area
The trunk is a different story. It is connected to most cars’ floors unless you drive a sedan where the trunk is separate from the cabin.
The main insulation idea is the same as butyl rubber panels, but if you install subwoofers, you should especially well insulate the trunk lid to avoid rattling sounds.
Also, if you have a spare tire in the trunk, it is a good idea to add some sound absorbing materials to that area too, to avoid noises from wheel vibrations.
#6. Engine compartment
The engine compartment is the last area where we can improve the acoustic in our car. Adding butyl rubber mats or foams to the firewall, fenders, and the hood is essential to reduce engine noise.
Adding butyl rubber mats or foams to those areas will make a significant difference in the engine noise but be careful and use only panels that are heat resistant.
#7. Wheel wells
The wheel wells are one of the most critical places in the car when we want to achieve good acoustic.
The noise comes from the wheels and the suspension, so it is essential to ensure that those areas are well insulated.
The good thing is that wheel wells can be insulated from the inside and outside, depending on our needs or the car’s construction.
If we want to achieve the best possible results, use a soundproofing spray like Spectrum Spray-on Deadener, but you can also purchase a product like FatMat and apply it to the outside of the wheel wells.
Both products work great, but the self-adhesive butyl rubber is easier to apply and gives equally good results.
How Much Sound Deadening Do I Need?
This is a difficult question because it depends on many factors like the car model, the size of the car, and the type of soundproofing materials you use.
Generally, for a small car, you need between 75 and 100 square feet of butyl rubber mats or foams, and for a full size car, between 120 and 150.
Of course, this is just a rough estimate, and the amount of sound deadening you need may differ.
If you want to be sure, the best way is to contact a professional who can give you a more accurate estimate or check the online calculator on Secondskin.
Which Soundproofing Materials Should I Use?
When searching for sound deadening, you will see a wide selection of materials with different thicknesses, shapes, and prices, but which is the right one for your car?
First, it depends on the part of the car you want to soundproof and whether the material must also be water or heat resistant.
For example, foam panels that work great when installed in the door will do more harm than good when placed under the hood. And vice versa, soundproofing panels with silver foil that absorb heat are not needed on the floor, where is always a lower temperature than on the roof.
Below are the most common material types we use in our cars:
#1. Wool sheets, also known as felt mats, are the simplest and cheapest sound deadening products. They are thick, have excellent noise absorption, and offer easy installation. However, they quickly absorb water which can cause corrosion, and they are heavy.
Wool pads are often used as factory soundproofing of floors and wheel arches and placed directly under the floor carpets.
#2. Bitumen sound deadening pads are the other cheap option for car insulation. However, they are heavy and tend to crack due to their stiffness. Also, they must be heated to become more elastic before sticking them to the metal parts.
Bitumen panels reduce vibration and are excellent for large flat surfaces like floors or trunks. However, they are not the best choice for the door and roofs because of the high temperatures in the summer that can cause the rubber to melt.
#3. Butyl represents a higher level and is one of the best sound deadening materials. Butyl mats are more expensive but provide better damping noise protection than bitumen.
Also, butyl can better handle extreme temperatures, which means there is no risk for the butyl panels to break or melt.
The aluminum layer that covers butyl panels provides heat protection in areas with high temperatures. As a result, they are perfect for sound deadening engine areas and other parts of the car.
#4. Sound deadening foams have an additional benefit over rubber mats. They can reduce high-frequency noises, such as from the wheels or wind.
This is why they are often used on the wheel arches and as a second layer on the floor and inside of the door panels placed right on top of the butyl mats.
Can I DIY Soundproof My Car?
It is possible to soundproof the car ourselves at home, and I did it a few times. However, this is a more complex task and may only bring results if it is done correctly.
First, you have to choose suitable materials and quantities. Next is disassembling the entire car interior, and although it may not sound complicated, it is important not to damage anything, tiny plastic mounting clips.
Another important thing is to precisely measure and cut the sound deadening panels to ensure they match. Do not leave any free spaces or gaps that may cause noise not to be reduced to the level we want.
The doors have two layers of metal sheets. The outer one is painted from the outside, and the inner panel, holds all door equipment, including speakers and door handles.
For the best results, you have to cover both door panels with soundproofing materials.
The outer side of the door has to be covered with a butyl mat that is sound and vibration resistant. The inner panel, in addition to the butyl mat, should be covered with either rubber or foam panels that offer better noise protection.
Let’s look at the example of steps to be taken when a sound deadening car door is:
#1. Prepare the right amount of selected soundproofing materials. For example, the door needs around 9 square feet of flexible butyl panels and the same amount of rubber or foam mat.
#2. Remove the plastic door panel. Depending on the car model, we need to loosen the screws, debond the mounting clips and properly disconnect wires to the windows and mirrors steering. In cars with manually lowered windows, we have to remove window handles.
#3. Remove the interior door handles, speakers and covers, other plastic elements, wires with their clips, and plastic or paper sheets.
#4. Clean and degrease the raw metal surfaces.
#5. Place prepared butyl panels inside the door and stick them to the outside door panel. This is tricky because we have to push the rubber through the holes (also through the speaker holes), which are small in some cars.
At this point, you have to be careful not to block any drain holes at the bottom of the door.
#6. Stick a prepared rubber or foam mat to the metal door panel from the cabin side. Make sure there is left space for free movement of the door handles and window mechanism.
#7. Put back in place all plastic clips, connect wires and install speakers. At this point, we have to test if the speakers, electric windows, and mirrors work correctly.
#8. If all equipment functions correctly, assemble the door back together. With additional layers of soundproofing mats, you may need to push plastic door panels harder to make sure plastic clips click correctly into a metal door.
The noise in a car is one of the most common reasons people replace cars. But unfortunately, many think that the only way to reduce noise in the vehicle is to get the new one.
However, most new cars are also too loud, and with time, driving is not as comfortable as you can expect.
It is also worth mentioning that better sound insulation is one of the criteria distinguishing cars’ premium class.
You can reduce noise in the cabin without replacing it with a new one, and you can do it by soundproofing your car. This is a cheap and effective way, thanks to which you can increase driving comfort and start listening to music of better quality.