Here Is How Acoustic Insulation Makes Audi e-tron Really Quiet

JAN 8 2019 BY MARK KANE 18

Electric cars are quiet but, but not without insulation

We all know that electric motors and electric cars are quiet compared to internal combustion engines and cars. This is one of the first things one would notice when switching to electric. The car is turned on and quiet, without vibrations. You can also talk without raising your voice.

However, because there is no noise of the engine, after a longer time you start to adjust and recognize tons of other things – parts that are not exactly aligned, tires, high-frequency noise from the motor/power electronics or some fans. To make electric cars quiet without those other sounds, manufacturers need to spend some effort.

Autogefühl noted in one of the latest reviews of the Audi e-tron that car is very quiet, even at high speeds (quieter than Tesla, for example). When we dig deeper into press materials we can spot there is a hell a lot of acoustic insulation in e-tron.

Audi tries to reduce the noise at the source – like on the motors or wheels – as well as isolate the passenger compartment from the rest of the car:

 

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18 Comments on "Here Is How Acoustic Insulation Makes Audi e-tron Really Quiet"

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Perceived sound is a weird thing.

You might think that less engine noise would be a good thing, but since we can adjust our hearing, we start to notice other, quieter sounds and that can be worse. Especially high frequency sounds can be annoying. We are evolutionary trained to listen for a babies cry, so high pitched sounds increase adrenaline levels and make us stressed.

But music also helps, so if you are annoyed by the motor whine, just turn up the music.

Or audiobook/podcast. Between driving and skeptics guide to the universe, I hear nothing.

Yep. When my wife and I got our first EV we quickly started listening to something — music, sports talk radio, usually — whenever we weren’t talking to each other in the car.

When I give newbies a ride in my car, I make a point of turning off the radio and HVAC and pointing out how quiet it is. Almost universally people love it, even though they think it’s a little weird to have zero car sound while waiting at a red light.

We listen to audiobooks or do a game where everyone can choose 2 songs in a row to listen too, one long song after I choose “Echoes” by Pink Floyd and “Autobahn” from Kraftwerk one time. After that my kids and wife changed the rules.
It’s fun to drive electric, can’t go back now to an ICE. I get really annoyed when I have to drive with someone else in their ICE. So if there needs to be a driver I always volunteer even if that makes me “bob” (not drinking when going out).

Thanks for the reminder of “Echoes” by Pink Floyd. It’s been decades.

A little AC/DC will fix that right up.

Or Kraftwerk’s “Autobahn”.

Actually, our i3 is so quiet, I’m hearing music from OTHER people’s cars. LOL

I isolated my Model S in the doors, sound system also was improved during this, still need the wheel cases, and would like to use some of this Open-Pore PU foam on the motor I am sure this will help the whining motor sound, if somebody make a Tesla Model S kit, I will be the first in line

Noise is something that’s always annoying in cars. Audi have decades of experience in reducing noise so it makes sense that they can make their vehicles even quieter than Tesla. It’s worth pointing out that not all ICE vehicles are alike, and premium ICE sedans (and even Trucks) are just as quiet in normal use as something like a Model S (except for hard acceleration) in part because of the amount of effort manufacturers have put into noise reduction. Engine noise is a pretty small factor in the grand scheme of things for a powerful vehicle. Road and wind noise are far bigger annoyances, and manufacturers have spent a lot of time trying to deal with it – one of the biggest issues is wind noise over wing mirrors, in part solved by developing the camera based system Audi have. That said, having an even quieter car is good in many ways and EV is another way of moving towards that result. Sitting in a smaller, cheaper vehicle where you have to shout to be heard at highway speeds is annoying, and it’s refreshing when sitting in an truck/SUV and being able to talk normally, so an EV SUV, with… Read more »

Agreed, it’s totally up to how willing the MFG is to spend the money. I don’t like them but roll down the road at 45 mph in a new Lexus LS and you will think you went deaf.

As you know, there is a difference and that is EV’s are quieter both inside and out.
No noise pollution to annoy pedestrians. 🙂

Most of the exterior pedestrian noise is going to be wind and road noise, not engine noise either, so it’ll make little real world difference – One of the reasons EV’s only need artificial noise at very low speeds.

A move to EV’s would reduce the chance of obnoxiously loud exhausts and people (purposely) accelerating hard and making the engine actually work however.

Wouldn’t it be nice to live in a world where the police actually did their jobs and gave tickets for noisy exhausts, loud radios, too dark tint, non-DOT-approved catastrophic-failures-in-waiting shade-tree modifications, shattered windshields, blinding aftermarket LED headlights, etc? US traffic law enforcement really is the Wild Wild West.

Or warn them that they’re about to run over…

I haven’t noticed an increase in my sensitivity from driving my PHEV in electric mode, but driving my wife’s ICE/Hybrid on a long trip this weekend was PAINFUL to my ears. Road noise, engine noise, wind noise.

Compare Audi’s intense focus on these acoustical details to Tesla. IIRC, Elon Musk made an executive decision on the assembly line floor last spring to eliminate one layer of acoustic insulation between the Model 3 body floor and the battery because the automated “flufferbot” was unable to consistently install it correctly and it was holding up the assembly line. He said it didn’t make any difference in the noise, but NHV is a subtle and complex game. I wonder if Tesla’s NHV engineers who specified the product in the first place and probably did a lot of modeling + pre-production testing actually concurred with Elon’s decision.

Slag on Audi’s battery tech or (perfectly adequate) range, but you can’t say that the E-tron is a poorly-engineered vehicle – Audi knows how to build a car.