It can be really annoying trying to chat or listen to your favorite music while you're in a noisy car, worse if you're taking a long trip. Modern electric cars are extremely quiet, while Jeeps, old cars and trucks tend to be quite noisy.
In this article I want to share with you some of the techniques I have learned over the years to soundproof the car, tricks that can reduce DRASTICALLY (so I do not mean small imperceptible differences) the noise coming from the road and from the engine of the vehicle, to make the driving experience much more pleasant and comfortable.
The number one way to reduce street noise
The best way to soundproof a car by reducing road noise in a sustainable way is called Dynamat (Amazon link). It is a "shield", a carpet of soundproofing foam that can be inserted for example under the mats in front of the driver and passenger in front, or in the car door or in the trunk.
The Dynamat (Amazon link) absorbs the sound coming from the wheels, preventing it from propagating inside the car's cabin.
But it's a bit expensive, fortunately on Amazon there are also cheaper alternatives, such as this one (Amazon link). It is a product highly recommended by users of American forums for those who like to modify their cars.
Installation is very simple and requires no special technical knowledge. If I can do it, you can do it too.
Lift the car's factory floor, rest the insulation mat and stop. Insulating foam has an adhesive on one side, so there is no need to mess with glues and silicones either.
The degree of soundproofing that is obtained obviously depends on how noisy the car is and how much area you can cover with the insulating foam.
How to soundproof the car's hood
After isolating the front part where the mats are, you can switch to the car hood, since a lot of the noise emitted by the rear wheels comes directly undisturbed inside the passenger compartment. This is especially true if the area of your trunk is large (think of a station wagon for example).
If, on the other hand, the vehicle's rear seats extend almost to the end of the car, or if the bonnet is very small, soundproofing will make little difference.
If the noise coming from the street is really unbearable, or if you have a problem with the heat coming from the car roof, you might consider adding reflective insulation to the insulation mats too.
The heat-reflecting panels as the word says serve to isolate from the cold or heat, but not everyone knows that they also work as soundproofing material, in fact they are excellent sound screens.
I didn't even know it before using them, and then I was surprised by how much noise they filter from the outside of the vehicle inside. When I found this thin sheet in my hands for the first time, I didn't think it would help much, but with time and experience I had to change my mind.
The good thing is that it can be used in tandem with insulating mats, and is the right solution for those who want to make their cabin bombproof.
In this case before applying the insulating mats, simply spray the 3M adhesive (Amazon link) on the floor of the car, and then place the reflective insulation sheets. Once the adhesive layer you applied has dried and the sheets are in place, just glue the panels from above as explained above. In this way you will get the maximum level of acoustic insulation possible, and in addition also an excellent thermal insulation.
Which car parts can be isolated acoustically?
The best place to start placing soundproofing material is, as already mentioned, the part under the driver's and front passenger's rubber mats.
This is because it is the part where you will spend more time in the car, and in this way you will block the noise coming from the wheels, the main source of annoyance.
But the second reason is that this is a delicate place as it works as a resonance box to transmit unwanted noise coming from the vibrations of the road through the whole cabin amplifying it.
The second most important point to cover is the front and rear wheel pass. At this point I suggest you pass some antirombo, which can be sprayed from a can, like this one you can find on Amazon. Or applied with a brush, with this other solution, directly on the wheel well and WITHOUT DILUTING.
The third area to look after is the "floor" under the floor mats of the back seats, this does not communicate directly with the wheels and tires but can also be an unwanted sound box.
The last part to deal with, in my opinion the least important, but a fundamental point to consider for those who like to do things right, are the car counters.
If you own a Jeep it is a good idea to soundproof them, because in these vehicles the doors are notoriously thin.
However, this step is to be considered only for those who have practical and manual skills, as it is necessary to first remove the panels from the door walls. Also in this case I recommend the application of Dynamat (Amazon link) or insulating mats, to be glued in the space between the two panels.
How to maximize the soundproofing treatment
Imagine you are trying to soundproof your home windows. If there is someone who is talking outside, the window will block most of the sound, and it will not make you hear it. Now imagine making a tiny little hole inside the window pane. Now you can hear the person talking as if there were no filter between you and her. Even a very small hole lets in a lot of sound.
This is because the sound passes where the air passes. We must remember this. If you can pass a little air through it, the sound can also pass by.
The best thing to remember when applying this insulating material is to make sure not to leave even the tiniest space between the panels. For example, when applying insulating foam it is important to cover the ENTIRE AREA below where the driver and front passenger feet rest. I recommend using duct tape to cover any small spaces.
What level of soundproofing can be expected from this treatment?
I have not performed any scientific tests, but I can say that arranging the foam alone can cushion about 40% of the noise of the vibrations coming from the road.
The louder the car you work on, the greater the effects.
Older cars tended to be built with larger factory-equipped areas of almost zero insulation, so in this case the improvement could be almost miraculous.
If you own a new car and want to make it as acoustically comfortable as the most expensive and best-designed cars, this treatment will help you get closer to the desired result.
I advise you to download a mobile application to check the decibels inside the running machine, and take a test before-after the treatment. Remember to turn off the air conditioning before doing this test, and I would very much like to know below in the comments the degree of decibel reduction you managed to get.