How active noise cancellation for automotive works | Hacker News Reader

How active noise cancellation for automotive works

silentium.com

Actual title of this marketing piece with no actual detailed technical information on "How active noise cancellation for automotive works":

Advanced, broad-band active noise cancellation now available in cars

One thing to keep in mind is that you may not be able to modify the car stereo in the vehicle with this technology.(without some other help)

My Jeep has this technology, and I added a more powerful subwoofer which resulted in a random intervals of 50-60hz coming out of the sub to cancel out the engine noise. It drove me nuts until I found a PAC audio interface that would give me a clean signal and bypassed the ANR.

What's your opinion of the ANR system in your Jeep? Was it effective?

I think the main intent was to reduce the volume of the cylinder deactivation cycle(it does drone a bit in 4 cyl mode) but it rarely activates that mode unless I put it in "Eco mode". I would use that if it didnt also remap the throttle response to be so lazy. It adds what feels a few seconds latency to the pedal response.

I can say without a doubt that having bypassed it completely has had little to no audible effect. My Jeep came from the factory with a loud exhaust(is a Grand Cherokee SRT- so no off road intent in this vehicle) and I kind of like the way it sounds(though it isnt really that loud tbh)

> it does drone a bit in 4 cyl mode

sounds like a 4-banger subaru outback...?

Interesting! Just curious, what model jeep has this as an option? Would be interesting to see how retrofit-able this is into older, very noisy Jeeps.

Ive a Grand Cherokee SRT- I suspect it would likely be a hard problem, and may require a somewhat sizable car audio system (If you were referring to something like a CJ-7 or the like)

The integrated audio, infotainment and ADS systems on more recent cars can make it quite difficult to install aftermarket stereo components unless you're willing to give up features such as rear/side cameras, in-cabin noise reduction, etc.

Well the adapter I bought is a MITM attack on the CAN BUS and extracts the un altered audio signal from the head unit. It does the following: 1) Ignores ADS 2) does not apply the vehicle equalization that sounds 'good' to the average listener. 3) provides 5v line level output for front rear and subwoofer outputs. 4) retains all safety functionality (front collision detection beep, blind spot detection, and backup sensors

if you want to see more its made by PAC audio

https://pac-audio.com/

Just went back to their site, and looks like they sell a bypass kit for ANR, so maybe Im not the only person that wasnt a fan...

https://catalog.pac-audio.com/catalog/amplifier-integration-...

Also note a lot of luxury performance cars have the opposite - the engine noise is amplified by the stereo system. It makes sense as sounds is so dampened now but you want to hear that sweet engine note when you hit the gas.

Ford Mustang does this too, except it's not amplification of the engine, it's actually pre-recordings of engine noise pumped into the sound system when you step on the gas.

This seems so... American.

You'd think so, but BMW did it first, as far as I'm aware. Anyone know of an earlier system?

VW also did it quite early in the Golf GTI, but I think that is around the same time (2011?), although not with recordings but actual engine noise, or so they claimed.

You could argue that being able to hear the actual engine noise more clearly does have some practical benefits especially with a manual transmission, although only really if you're driving it around a track (or if it would be totally silent inside otherwise).

I know the E-Golf does generate sound to warn pedestrians. Most modern upper class cars have noise cancelation by now. It is ridiculously silent in some of them.

This 2012 article seems to be a good overview:

https://www.caranddriver.com/features/a15117726/faking-it-en...

At that time, Porsche, VW, BMW, Ford, and Lexus had various types of system to enhance engine noise.

It seems Porsche and Ford channeled the real sound through mechanically. VW started off doing that but then switched to an electronic system called Soundaktor. Lexus hired Yamaha to do an electronic system. BMW did it electronically.

Things may have changed since then. The article makes it sound like Lexus did it before BMW. And probably VW too, although that's less clear.

My 2004 BMW did this mechanically: there was a tube connecting the passenger compartment with the air intake to pipe in that sweet engine noise. (There was a membrane inside to prevent actual airflow). Interestingly, the sound was actually too loud, so they stuffed some foam blocks in the resonator pipe to deaden the sound. But if you really wanted extra noise just remove the foam!

It's very Disney Land. A superficial facade you're not meant to look behind.

I drove a mustang recently and it shone a mustang logo on the ground when you opened the door.

To me american would be to actually have a v8. (like italian would be a 12).

But honestly this really reminds me of shitty pro-look electronics. Like crappy RGB car stereos in every corner of the world, or old style "fake stack" home audio system with a loudness button and permanently wired plastic speakers with 22 gauge wire.

As do many others. I was shopping a VW Golf R. Apparently there's a motor at the base of the windshield with an offset weight. So it adds vibration.

I can somewhat understand doing this for people who expect v6 noises from v4 turbos. But not providing the ability to turn it off seems silly.

I've been an avid ANC headphone user for some 6 years or so.

The current gen ANC is remarkably good. The issue I had with previous generations was that a carrier wave (for lack for better word) was always audible, which admittedly wasn't as bad as the noise it was cancelling, but it could be annoying for home use when you just wanted to cancel the fridge, AC or similar room tone humming.

With current gen ANC from the good brands this sound is very quiet, in some cases bordering on inaudible. Stuff just goes quiet. It's very impressive.

Thanks for your comment. I am shopping for a new ANC headphone lately.

May I ask what headphone you are using?

Not OP, but new Sony WH-1000XM4 are amazing.

Using Sony WH-1000XM3 myself. RTings has tested most ANC headphones on the market and published their measurement (not gut feeling) results: https://www.rtings.com/headphones/tests/isolation/noise-isol...

Probably would get Sony WH-1000XM4 myself this time (they pause automatically when taken off). Have not personally used Bose ones since QC35, but some people like QC35 II better for long term use. Also Sony XM3 microphone is not very good for phone calls. I have heard XM4 has fixed this, but can not confirm.

I love my WH-1000XM3s and was probably responsible for at least 3 of my friends getting pairs... but yes, agreed, the call quality is pretty poor.

Fantastic noise cancelling headphones, though.

I tried both the Sony XM3 and Bose NC 700 and went for the latter. Mostly personal preference for size, weight, fit as ANC and sound quality are pretty even. The Bose though is superior for calls. Never had a problem.

The XM3 had a terrible design flaw which made it basically unusable in cold climates. If the XM4 fixed this I would A/B test them with the Bose 700.

The XM3 had a terrible design flaw which made it basically unusable in cold climates.

What was the flaw? I've almost decided to buy a pair.

I see now I accidently replied to the wrong comment and got downvoted because of it (presumably)...

Anyways it's well documented on forums and videos, the touch pad on the earcup causes erroneous inputs causing music to stop and play randomly when outside (only if it's cold though).

This was a while ago now - but Sony released an update that allows you to disable the touch buttons if you're affected by the issue. I use my XM3's in freezing temperatures often and have never had any issues with the touch buttons - so mine are still enabled.

I have been using a Sony WH-1000XM3s for about 10 months now. Got it just before WFH and has been a life saver.

Question: anyone else feels fatigued after a long period with ANC on? Ears ringing after?

Because of this I use mine sparingly.

I do feel fatigued after, but, I think, not for the reasons you expect.

I noticed that when I take out either airpods pro with ANC or my WH-1000XM headphones (the first gen), I feel uneasy and overwhelmed, with some ringing.

But then I realized it wasn't due to ANC, it was due to all that constant noise around me. So if I went without that noise for an hour or two and then got introduced back to it, it takes me a solid minute or two to get adjusted. All those random noises, like water moving through pipes, wind outside, air conditioning, etc. become super noticeable and end up just overwhelming me by being introduced back all at once. I've been observing this kind of stuff for a while (had my WH-1000XM headset for over 2 years), and I got better at adjusting back over time. But i still get those shorts periods of time immediately after, when that noise ends up flooding back and just making me hyper aware of it.

Do you know of any ANC solution that works well (i.e. should be much better than foam earplugs, and preferably remove all sound no matter what) and is usable for sleeping?

The only product I know is the second iteration of Bose Sleepbuds. It might not fit the bill though, and they're quite expensive imo. They call it noise masking tech, so it depends on what you're looking for, but they're meant to be a earplug replacement kinda thing.

They feel amazing while lying down but that's all I know personally, the deal breaker for me is that you can't listen to what you want on them, only the sounds they've added in the app.

I've been waiting to see active noise-canceling technology applied to more than just headphones. Imagine living next to a busy highway, near an airport, or above a bar, and being able to dampen the noise through an array of active noise canceling devices.

That is a much harder problem.

Your headphones can record and generate cancelling noise because they don't move relative to your ear (and are so close that they receive the same noise that has to be cancelled).

Once you are moving out and about around a room, a system such as this one would have to account for all the sounds coming in from all different directions, then track your position to figure out how all those will be reaching you, have a good model of how sounds bounce in your space and finally beam the cancelling sound straight to you (because cancelling noise is still noise, and if it starts bouncing around it will worsen the problem instead of helping it).

That's why the best you can hope for (today and for many years to come) is just soundproofing. We can do amazing things already in this front.

It would be amazing if even if we’re possible for a bedroom. The positions of the occupants are predictable. Cancelling out road vehicles, trains, planes (loud drunken voices?) would be a huge boost to countless people across the world.

I think I just found my next RPi project. Our sprinter van is great and the thinsulate insulation I added cut down on noise a lot, but the road and wind noise on long 70mph multi-day trips gets a bit much.

[ EDIT: it seems that the cancellation signal plays out of the same speakers used for in-car audio. I wonder what implications that has ]

I’m not sure if thinsulate is the same thing, but you might also want to look at Mass Loaded Vinyl with a closed-cell foam underlay (can be bought together as one sheet). It took me quite some reading up on road noise to realise that MLV, and not the butyl/Dynamat kind of sound deadener, is the key to reducing road noise, and is what luxury car manufacturers use.

I’m planning to do the floor of my RAV4 in the next few weeks. never taken the seats out of a car before, should be interesting.

I just did a bunch of research for this on a new car I'm getting. From what I was able to learn, the CCF and MLV block road & tire noise, but the butyl sound deadener products are still important to stop the sheet metal from vibrating and to stop resonance in the door cavity & trunk.

25-50% coverage with butyl directly on the sheet metal is enough, since it doesn't block sound, just absorbs vibrations. If you tap your doors or trunk lid, or if you swing the door shut, the sheet metal will have a tinny hollow sound, but after butyl all of those become more of a solid 'thunk.'

Overall, the butyl stops the sheet metal from making its own noise and from amplifying the tire vibrations; then the entire surface needs to get 100% unbroken coverage of the CCF/MLV to block all types of noise from entering.

Demonstration: https://www.youtube.com/watch?v=_ur_Rhi5js8

I think the affect of the butyl dampener on actual internal vehicle noise is minimal. I've done that part, and my doors close thunkily now (not that I ever cared) but the car is just as loud as ever inside. I think that unless you're going for high-performance audio, there's really not a whole lot of value in the sound deadener.

> 25-50% coverage with butyl directly on the sheet metal is enough

This is true, you see in a lot of the professional installer videos that they will cover the whole surface in the deadener, but it's not necessary.

Reasonable MLV article (advert but OK): https://www.secondskinaudio.com/sound-blocking/

And another article aimed at home usage: https://www.snoringsource.com/mass-loaded-vinyl-alternatives...

Sorry for the delay in responding ... been on the road in our van :)

MLV is an entirely different material and is used for an entirely different purpose than thinsulate. It is not useful for stopping road/wind noise, but does help to dampen vibrations and resonance in the metal body of a vehicle. It is a dampener, and will not cut down much on the type of noise we have left in our vehicle.

MLV has a problem when used for automotive uses. To be maximally effect, it requires an air gap on both sides and must not be rigidly mounted. Apply MLV to the surface of a vehicle body will do approximately zero for noise. MLV is widely used for sound reduction in buildings, where it is much easier to mount it in ways that allow it to significantly dampen sound transmission.

High end cars use thinsulate as well as dampeners. Most Mercedes and Lexus' (at least) are lined to the gills with automative thinsulate, along with dampeners applied in critical locations.

The RAM heavy duty pickups have a system like this, where it's a lot harder to prevent or cut down noise of a big diesel engine, HD transmission, tcase, and tires. It really works well in practice.

Meanwhile those of us not inside the vehicle get to enjoy the full force of these irritating sounds.

Woah, the video is the first time I learned that Volvo was bought by that Chinese car company Geely (who also make the Lynk & Co car used in the test).

Something I’ve always wondered about ANC and never been able to find an answer to. I have Airpods Pro, with ANC, and since iOS 14 my phone displays a safe heating indicator with the dB hitting my ears from the pods. This level does not change when ANC is activated, but intuitively I’d assumed that it produces extra noise.

Does ANC actually cause destructive interference, meaning no noise is in fact reaching my ears?

Yes, destructive interference is the whole point of ANC.

ANC interferes destructively with what was happening some milliseconds ago. If the noise is irregular (like speech) the ANC signal will “miss” and become net new sound.

I could really use this technology in my bedroom, to cancel out the hum from a noisy rooftop ventilation fan.

This spells good news for electric cars, which seem to have far less sound-deadening material, and indeed far less of any material in the cockpit in order to keep a low weight. I’ve been in two Teslas and the noise is awful compared to my 14-year old Audi, which is a delight over long distances. This could really be a game-changer for those of us who covet comfort. That said, cars are probably not the future here in the EU, but still. If I want to enjoy engine noise, there’s motorbikes.

I've only ever test driven a Model S, and seen multiple Youtube videos (usually of owners showing off a new barely contained beta feature), and that explains all the road noise.

I thought it was just my imagination, or the awareness of other noise given the lack of drivetrain noise. My 7 year old Volvo S60 seems quieter than the Tesla at speed, and it's a diesel.

I'll keep daily driving my classic cars. Who needs a music system when you have them :-)

I wonder how many others easily get motion sickness in a car or other vehicle with a lot of noise dampening and otherwise "isolation" from the outside. I've been in some of these newer cars and rolling down a window, thus increasing the sense of noise, was one way to avoid it. On the other hand, I didn't experience the same in cars far noisier and with less dampening.

Just curious whether using noise-cancelling headphones gives you the same reaction? Or would you only notice it if you were moving?

Or would you only notice it if you were moving?

Exactly. Noise-cancelling on its own doesn't provoke the same feeling of nausea, since I'm not moving.

I often use my airpods pro while driving with ANC turned on and get absolutely no nausea.

Since they cancel predictable noise, I also feel my driving is actually safer (a noise like a siren would sound relatively louder than before).

In the youtube videos on the page, it shows a big microphone mounted next to the passenger's left ear.

My first question is: is this for measuring the sound waves for the purpose of the video, or is it part of their ANC system?

If it is part of their system, how much worse does the system perform with a less well-placed and conspicuous mic?

I'm pretty sure the mic is part of the test/measurement rig, not part of the ANC system itself.

Hmm... The second demonstration video at the bottom of the page seems misleading, because to show how it works with music they didn't show the actual recording with music playing in the car, they're just putting music on top of the recorded noise in post-editing.

Is this really a good idea in traffic?

Doesn't seem bad, because ANC doesn't cancel out sharp sudden noises, it only cancels out repetitive semi-constant noises (like AC or engine sound). So all the essential sounds on the road, like sirens or horns or impact or sudden tire burn, will be heard perfectly fine, while all the annoying constant noises (like the road or engine) will go away.

Try it next time with ANC headphones: ask someone to play a siren sound on speakers. I can guarantee that you won't hear the siren any less than usual. In fact, you will hear it better, because it won't be overlapping with all the other random background noises. Similar, but to a lesser degree, with speech. I was able to have full-on conversations with people while wearing headphones with ANC turned on (in the office), zero issues. Which is kind of a scenario that ANC cannot currently handle when it comes to using them in an office, since it won't cancel out the sound of someone randomly kicking their desk or slamming something on it.

Very impressive

The test movie looks/sounds impressive until you notice "with headphones" in the corner.

I can get noise cancellation with headphones today, and it's very good.

I think this means "wear headphones while watching this video to get the full experience of what it is actually like"

> The pressure waves from both the unwanted exterior noise and manufactured anti-noise reach occupants’ eardrums at exactly the same time and cancel each other out.

What happens if your ears are not exactly where the system thinks they should be? If you are taller or shorter than they expect? If you are not sitting in the drivers seat? If you lean over?

My guess would be that the system makes things worse more often than it makes things better, if it relies on your ears being in the correct position.

The wavelength of middle C is something like 2 feet, so if your ears move by 1 foot will you be getting double noise, rather than zero noise?

Note: The wavelength of C4 is ~1.3 meters or about 4 feet 3 inches. C5 is half of that, or around 2 feet.

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