If you want to reduce noise in your car interiors/ soundproof your car, let me make one thing clear at the outset:
There is no silver bullet.
You will have to reinforce multiple areas of your car in order to get truly satisfactory results.
Like I always say, soundproofing isn’t something you just do in a localized manner. In this case, you have to take the entire car system into account, see where the maximum sound leakage occurs, and then figure out the best ways to reduce road noise.
In this article, I’m going to list out the best possible ways to reduce :
- Road noise
- Wind noise
- Engine noise
I spent a few days researching this topic and I believe this is the most comprehensive article you’ll come across on ways to soundproof your car.
So, let’s roll on with it, shall we?
How To Reduce Road Noise In Your Car
#1 Undercoating Your Car
Rubberized undercoating is a pretty nice way to soundproof the underside of your car, and also protect it from rust, grime and dirt.
If you do it yourself, it won’t cost you much- but you will need to take out 4-6 hours on a weekend for this.
All in all, you’ll just need to buy a couple cans of spray for this, and that’ll set you back by about $100. If you so prefer, you could also leave the car at a service centre that will do the undercoating for you, for about $50-100 more.
Keep in mind though, that undercoating needs to be done the right way to be truly effective. You can read more about it in this post that I wrote.
#2 Getting The Right Tyre
Few things that contribute to a quieter car tyre:
- Narrower tyre size
- Softer rubber composition
- Smaller grooves for traction
- Smaller voids between grooves
Which is why, generally speaking, your standard car tyre is probably the least noisy out of all options. It has a narrow build and smaller grooves than other types.
Tyre noise also depends on how fast you’re driving and the surface you’re driving on.
For instance, if you have one of those offroading tyres that have bigger grooves for traction, and are driving on a mud path- of course there will be more noise.
Another issue is that of wear and tear.
Directional tyres, for instance become louder with wear and tear than non-directional ones.
Also, uneven wear and tear may happen if there isn’t proper wheel alignment. This is another reason for tyre noise.
#3 Add Vibration Dampeners In Your Car Flooring
Sound travels through vibrations, regardless of what medium it is travelling through.
You clamp down on vibrations, and the noise levels reduce automatically.
This is the effect that adding vibration dampeners to your car’s flooring will have. In terms of effectiveness, I’d day this is even better than undercoating your car.
So what is a vibration dampener?
It can be any material really, it just has to be one that is thick enough, i.e: has enough mass to be able to reduce sound vibrations. Mass in fact, is one of the most desired traits in a soundproofing material.
I recommend Dynamat for this purpose. One pack gets you 9 sheets- each of which, has an area of 4 sq. ft each. In all- it’s good enough to cover at least 1/4th area of a sedan, which is good enough in most cases.
As a slightly more budget friendly buy, consider the Fatmat. I couldn’t really find any stark differences between the Fatmat and Dynamat, so you’ll be fine buying whichever of these you want.
The price difference seems more because of branding than anything else.
#4 Soundproof Your Car Doors
Similar to soundproofing your car flooring, you can also use a vibration dampening material to quieten road noise coming in through the doors.
You’ll have to be slightly careful while doing this, since you’ll have to cut the material such that it doesn’t interfere with the circuitry inside the door.
Here’s a good tutorial for installing Dynamat in your car door.
#5 Have a big trunk? Soundproof that as well
A big trunk acts as a diaphragm and amplifies the road noise coming in from the underside of the car.
If you have a small trunk space, you can probably skip this tip, but otherwise, this is a REALLY important thing for you to do.
In continuation to points #3 and #4, you’ll soundproof the trunk in a similar fashion.
#6 Soundproof The Wheel Arches
Not the most widely used method I could find on the internet- which is why this option is towards the bottom of the list.
Soundproofing your wheel arches consists of adding some soundproofing material(link to my post on 24 best soundproofing materials) to the wheel arches. This will muffle the sounds coming from the tyres- which can be a big source of noise.
#7 Line your cup holders
Hollow spaces, such as the cup holders act as a diaphragm for road noise travelling from the underside of the car.
In simple words, they’ll amplify the sound coming from down below, which is why, you should line them with an acoustic foam or similar material than can absorb reverberations.
How To Reduce Engine Noise In Your Car
#8 Muffle The Car Exhaust
The car exhaust can be a big, self-created, source of noise pollution for some people.
If your car exhaust starts screaming every time you rev the car a bit, the best thing to do is to attach a muffler to the exhaust.
A relatively low cost way of doing things than actually going about replacing the car exhaust.
#9 Soundproof The Hood Of The Car
The hood of the car is where the engine resides- which can be a big contributor to the noise levels, if not working properly.
The reasons for engine noise could be many, and probably they can be fixed as well. However, generally speaking, as any car ages, it’s engine will make relatively more noise than before, even in normal operation.
Soundproofing the hood of the car is as simple as lining the underside of the hood with some Dynamat, in order to absorb those sound vibrations coming from the engine. That’s pretty much all.
#10 Just Get A Louder Stereo
Ever heard of a white noise machine? It actually is an effective method of blocking out unwanted sounds by filling up your background with white noise.
That’s what I’m talking about here, in a way.
This is simply a brute force tactic. Get a better stereo that gives you an improved music experience and can block out majority of the road noise coming from outside.
You’ll find that the most effective thing is if your new stereo system has a better bass- because low frequency sounds propagate for longer distances than higher frequencies, and hence will block out road noise even more effectively.
How To Reduce Wind Noise In Your Car
#11 Reinforce Car Windows(maybe not affordable for everyone)
This one probably would require extensive modifications to the car such as changing the window slot inside the doors for a thicker window.
Probably have to redo the electrical circuitry inside the door if you have a power window, since now, the load will be more.
If can invest in soundproofing your windows you’ll get a noticeably better noise free zone inside your car.
#12 Add Insulation To Roof Of The Car
Noise enters your car from all sides- including the roof. Which is why, we need to look into ways to reinforce the roof as well.
Priority wise- I’ll put the roof as one of the last things you should soundproof in your car. This is simply because there isn’t a lot of direct noise coming in through the car roof while there will be a lot coming in through the sides, front, back and underside.
Anyway, what this method will require is to remove the existing roof lining in the interior of the car and line it with some soundproofing material- such as MLV(Mass Loaded Vinyl).
#13 Check if the door gaskets around the window are sealing
When you’re on a highway and driving fast(relatively fast than the city limits) you may notice a whistling wind sound coming in.
This is wind noise leaking through some gaps in the car system.
One of the gaps could be the gasket around your car windows. If it isn’t sealing tightly enough- you could be hearing an increased amount of outside noise because of that.
The most common reason is that the rubber seals that run around the door aren’t sealing well enough, and are letting wind, dirt and even moisture into the car.
The rubber seals will stop sealing correctly if aren’t taken care of will become brittle, over time.
The best way to bring your seals back to their original suppleness is to first clean them with any standard surface cleaner, in order to remove the dirt and grime.
Next, apply this product on the rubber seals and let it dry. Buff down any excess and you’re good to go.
#14 Get a car door edge seal protector
The other common reason for wind noise is because the air leaks through the small gap at the edge of the car door(when it’s closed)
To this end- a nice, inexpensive product that solves the problem is this car door edge seal protector. It gives a nice, neat finish to the car door, and provides a seal against wind, moisture and dirt from the outside.
Additionally- it’ll protect the door edges from nicks and bumps.
What Things Make A Car Noisy?
New Vs old Car:
This is more of a common sense thing than anything else- older car models are probably going to be noisier than a new model. It’s just that there always are some improvements and efficiencies that are brought in with every new model that somewhat provide less cabin noise.
Having said that- there is no truly quiet car out there, unless you’re looking to buy in the luxury segment.
Does it have a lowered chassis?
Many models today, in imitation of the ‘sports car’ look and feel have a lowered chassis. While these cars do look cool, they also bring in more road noise- literally due to increased proximity with the road.
Bigger cars, such as station wagons will generate more wind noise because of their increased surface area, which pushes more air away from it, as the car travels through it.
Also, big cars tend to have larger trunk spaces, which will, as I mentioned earlier, contribute to higher road noise.
What type of engine does it have?
Electric engines, of course will be whisper quiet- but then not everyone can afford a Tesla, can they?
Apart from that, diesel engines are noticeably louder than petrol engines in a day to day scenario where you’re driving around in a city. So a petrol engine is generally the better bet.
At highway speeds though, diesel engines can be even quieter than petrol engines.
How do the windows look?
Some manufacturers offer laminated windows which offer another layer of thickness to the window.
I’m skeptical this does much for soundproofing the car window because the change in thickness wouldn’t be substantial enough- you would need to install proper soundproof windows or reinforce the glass with another layer.
The suspension is basically the interconnection between the car tyres, spring system, shock absorbers and the chassis. The frame-work that holds the car together.
A ‘soft’ suspension means that the car goes smoothly over potholes or bumps in the road. A ‘stiff’ suspension will have the car airborne for a few seconds of it goes over a big bump.
Which is why, generally, having a stiff suspension contributes to more cabin noise.