Tesla Model 3 Soundproofing Guide (PART 1) – Intro to Noise reduction

My personal guide from soundproofing and doing noise reduction on my Tesla Model 3.

I am not an expert. Not a sound engineer. Not even a car person. I just hated the noise in my Model 3 compared to my old Lexus IS 250 and so I read hundreds of pages on the internet to learn every possible thing about soundproofing, sound-deadening, sound-dampening, etc. Took about 4 months of research. Wading through dozens of conflicting opinions, and ultimately decided on how I would tackle this massive project.

For the most part, there aren’t many experts out there and also not many people who’ve tried multiple methods. So I had to look around on all types of forums (car audio, soundproofing, audio engineering, etc).

Most people out there (even the more knowledgeable ones) are wasting time and money, buying the wrong stuff (overpriced or ineffective), using too many layers of it, or not doing it correctly/efficiently. I would say the worst forums to learn soundproofing are Tesla forums; they’re not as knowledgeable and/or doing half-assed bandaid solutions. The best are the car audio guys since they’re doing audio competitions.

I’ll do my best to cover everything you need but won’t spell out every detail to keep this guide as short and easily-digested as possible. If you’re attempting to do serious soundproofing, I will assume you are extremely handy with Google, tools, and have an adventurous DIY personality.

Let’s get to it!

NOTES:

• JUN 2019 – just bought the car and couldn’t stand the noise compared to my old 2007 Lexus IS 250. Wind noise, road noise, everything…it’s loud!
• AUG 2019 – switched out my stock performance model 20″ rims/tires to 18″ rims/tires. Very happy with the sound reduction (also improved mileage and smoother ride). But still want more noise reduction.
• SEP 2019 – added the door seals and top window rubber tubing. It’s a smal difference but I’m looking for something more aggressive. I spend a good month researching how to soundproof a car and then order materials to do it next month (hopefully before rainy season in California).
• NOV 2019 – Just finished intense soundproofing (right as the rain starts). Happy with the gains but still going to try other tactics. Mainly tackling wind noise and air turbulence around the frame. Will update the guide in a few weeks.

The Science of Soundproofing Cars

Main SOURCES of car noise:

1. Engine – more for ICE’s, but EV’s still have a small high-pitch electric wine.
2. Road – tires and suspension against the road. Harder tires, rougher roads, stiffer/sportier suspensions, all create more road noise.
3. Air – air “whistling” around or through window/door seals or simply carrying other sounds into your cabin.
4. Echo chambers – hollow spaces in your car, trunk and doors will amplify all sounds. (For Tesla Model 3, it’s more to do with the trunk area.)
5. Movement & vibration– wires, fasteners, trim, plastic or metal panels…all bouncing off each other when the car is moving.

Want to know exactly where your noises are coming from? First walk around your car and knock on all the areas inside and outside. From outside, knock all the panels and edges. You’ll notice some points have a thinner tin-can sound. It’s quite shocking. Then on the interior, knock on everything…the floor, the trim, the doors, the pillars, seats, console, dashboard. You’d be surprised to notice how much rattling they make with only a knock. Now imagine how loud it would be when the car is actually in motion!

Then, install a decibel meter app on your phone (there are many free ones). Then try holding the phone near different locations (windows vs floor, front vs rear, driver vs passenger side), and try it at different speeds. It’s probably safest if you have a friend drive while you do the measuring!

Soundproofing STRATEGIES (in order):

1. Vibration Dampening – You know the sound that cymbals make? Your car panels do that. The best tactic is to attach CLD tiles (combo of rubber and foil) onto metal panels to keep them from vibrating.
2. Decoupler – separating or securing things so they can’t make noise. Putting (closed-cell) foam between big panels, butyl rope around loose fasteners, Tesa tape on loose wires and other things. Tesla parts are taped/fastened really well, they don’t have this problem except for maybe the front seatbelts attachments by the B-pillar.
3. Blocking sound – create airtight barrier with MLV. It’s like closing the window to block outdoor noise. Some products even combine CCF and MLV layers so you have less work to do.
4. Absorbing sound – putting thick (open-cell) foam to absorb interior/exterior sounds.
5. Heat blocking – since you’ve already got the car opened up, can also install a heat-blocking layer (usually has reflective material) that also adds further soundproofing.

Main Noise Issues with Tesla Model 3:

• Wind noise leaking around windows, doors, rear view mirror, sunroof edges. I think there’s also turbulence of the air flowing past the rear-view mirror. I think this is due to them having so much windows that you hear the air turbulence all around them.
• Road noise leaking through floor and wheel-wells.
• Echo chamber in trunk, also passing through back seats. I think having a glass ceiling echos more than old cars with soft fabric on the hood to absorb sound (think like those big acoustic curtains in theatres).
• Noisy tires (especially if you have bigger wheels and stickier performance tires).
• Panel vibrations – lots of thin flimsy metal panels everywhere throughout the exterior and also also interior floor of the car. That big flat surface in the rear floor makes it a giant drum (unlike ICE with the shaft going through the middle to the rear seats).
• Suspension vibrations – Tesla Model 3 suspension is definitely noisy, especially if you have the performance one like I do. Stiff suspension turns all bumpy roads into frame noise.

IMO, most of the noise in a Tesla Model 3 comes from wind noise and road noise. The wind noise is heard as its whistles around your windows. Even if the seals are fine, there’s still turbulence. I even tested by taping up all the small gaps around my windows and doors (and then climbing in through the passenger side)…hahaha yes, my girlfriend thought I was crazy.

Road noise is mostly from the wheels and suspension, which then pass through your floor, wheel wells, and trunk areas. Not much is passed through the firewall (front area from your dashboard to the typical location of car engine), or the doors. Knowing this, I approached my car’s soundproofing much differently from how most others did it (going from back to front, instead of from front to back).

Main issues when soundproofing:

• Not enough improvement – this is a huge factor. That your effort didn’t improve much. So be thorough!
• Changed sound environment – some people seal off vent holes and/or absorb all the highs that the cabin like a droning boombox inside.
• Damage – what can I say? Be careful! Use proper tools and carefully protect your work area.
• Thickness – using too much material makes it hard/impossible to put certain things back together.
• Cost – most people don’t know what to buy or how much of it and that can get very expensive quickly. I will give tips!
• Time – it takes a lot of freaken time to do it right, especially if you’re not experienced.
• Weight – if you overdo it (out of fear), your car will be 200lbs heavier and little bit slower and less fuel-efficient. (Model 3 weight is 3600-4000lbs.)

IS IT WORTH IT? (And how much difference does it make?)

This is the question everyone wants to know. I knew going into this project that most people soundproofing their car out there did not get the results they had hoped for. Soundproofing can make a loud car more bearable, but it won’t completely shut out noise. Most people say they can’t even tell a difference except for their car sounds heavier and more premium (less tinny). An unfortunate many will say it wasn’t worth the cost and effort. After all the work I did, I found myself somewhere in the middle.

Here are my impressions:

• Yes, the car sounds quieter and more premium. To my naked ear, I would have guessed around a 15% noise increase.
• What about using a noticeable drop in DB using decibal meters? Initially, I thought it would be small and probably unnoticeable. This is because of what I heard from most people. They felt it sounded better but the numbers didn’t show any different. I also felt that decibel meters will pick up all sounds which may not match what the human ear picks up. But when I actually compared my test on the same freeway stretch traveling at 75MPH, I was shocked find an actual improvement of around 5-7dB (that’s as much as 40-50% reduction). The same stretch before was around 75-82dB, and after my soundproofing was only 70-75dB. I secretly don’t believe my work was that good but the numbers don’t lie. I even tried to drive on rougher parts of the freeway.
• Even still, it would be great to do a test side-by-side with a stock (unmodified) car. Maybe someone in Los Angeles & Orange County can volunteer?
• Blocking out high-frequency noises is easy, which most soundproofing does well. Blocking out low-frequency noise is very hard, requiring thick layers of MLV and not realistic for a car with tight spaces…which means car soundproofing probably won’t reduce this area much. (My car still has that loud womp womp droning echo sound in the cabin but it sounds more muffled.)
• Soundproofing your car won’t be like somebody turned the volume down on the noise. It’s more like somebody closed the door on the noise, but not all the way. You can hear it, but it sounds more muffled. Higher frequency sounds are definitely shut out better, but low frequency sounds are more or less the same but muddied!
• So yes, you will hear noise in your car but most of it is lower frequency (the thumps of your suspension going over bumps). Which means when you talk in the car or listen to music, it will sound clearer since less noise competes on that higher frequency.
• For those hearing lots of road noise, general soundproofing and changing your tires will be great. For those hearing lots of suspension noise (drum sound from cabin floor and trunk)…you might get better results out of a more cushioned suspension. (If you don’t know what suspension noise is, drive over rougher roads and/or with your back seats folded down. If the noise is louder, that’s suspension noise.) Of course, I called UnpluggedPerformance and the guy there told me he didn’t think changing the suspension would help with the noise at all. So that’s that.
• Yes, I do hear the wind noise a little more now since the road noise has decreased. But not so bad.
• Do I think it’s worth it? Yes. It was worth it for me. But I’m also tech-savvy, handy with tools and work from home. The process was much less technical than I expected but far more time-consuming that I expected. What I thought would take days, actually took weeks.
• Do I recommend you to try paying someone else (like an car audio shop) to do this work? I have mixed feelings. On one hand, I’m sure they would be very experienced and know how to tear your car apart quickly and put it back together without any damage. They would also work quickly since they’ve done this before. But on the other hand, I’m afraid they might be lazy on the difficult areas and take shortcuts that let sounds through. There are so many tricky areas that you wonder if anyone else would have the same attention to detail as you would. (You can look at my pictures and judge if you think if you think they will take the extra time or not.)

Future testing and things I want to try:

• Taping all the glass seams on the car ceiling (from the outside) to see if that makes any difference. Also taping all the door seams from top to bottom. And I guess I’d be climbing through the trunk and back seats? Hahaha.
• Shoving acoustic sound-absorbing foam in the cabin of the car. Also inside the wheel wells and in the trunk.
• CLD on the front side-fenders, and even on the outside-bottom surface of the floor somehow.
• Sound-dampening paint on the outside of the wheel wells behind the liners.
• Driving with the rear-view mirrors folded-in to see how much effect it has on the turbulence and wind-noise. (Is that even possible? Hahaha.)

Ready to start soundproofing your Tesla?

• Tesla Model 3 Soundproofing Guide (PART 2) – Quick and Easy Tactics
• Tesla Model 3 Soundproofing Guide (PART 3) – Exterior Soundproofing
• Tesla Model 3 Soundproofing Guide (PART 4) – Interior Soundproofing