Vehicle Noise Cancellation – or approximation thereof: virtual, mythical or …

[RJ_NSWheels]

Most of the exchange on this clearly widespread topic seems to go back 2-3 years. Since it’s still very current (believe me!) and still shrouded in mystery (polite euphemism) in certain quarters with an apparent interest in not laying cards on the table, I thought it worth posting as a new stream.  

 

Noted many tales of sound connoisseurs taking delivery of a brand new Octavia 3 (a pretty competent set of wheels in many respects) Elegance c/w Tech Pack and immediately spending serious money to upgrade the ‘Canton Premium Sound System’. That’s a bit of a contradiction, but – if sheer weight of decibels and sound purity result – there’s still the also reported issue of excessive cabin boom. [Margin note: 40% profile tyres, checked by swapping between quality, mainstream brands remain stubbornly harsh on this vehicle]
 

So … segue to Vehicle Noise Cancellation aka ‘Active’ aka ‘Dynamic’ that should come as part of the Canton kit. Has anyone tried to find evidence of the hardware, let alone verify if the cancellation tech works? Sure, there’s a black box under a front seat [amp] but no known access for plug-in diagnostics. Wouldn’t there normally be at least 2 sensing microphones – A-Pillars or thereabouts?

Puzzled … 

[norsko]

The Vehicle noise cancellation is just a very fancy way to say that the Canton amp adjust volume according to vehicle speed. Something that has been in several cars and HU in 20 years.

I dont think that you "spend serious money" for the Canton system. You get four two way speaker system, a center speaker and a micro "subwoofer", plus a ten channel amp and active crossover. Try to buy that from an another serious car stereo manufacture and see what it will cost.

 

In my 2016 L&K its all about wheel noise. The engine are very quiet, no booming and very little wind noise.

[SWBoy]

36 minutes ago, norsko said:

The Vehicle noise cancellation is just a very fancy way to say that the Canton amp adjust volume according to vehicle speed.

Aahhh! So it's NOT noise cancellation, it's noise masking by ramping up the volume (and adjusting the frequency response? - at least that's what the Bose system in older Audis did).

 

Proper noise cancellation needs more microphones that speakers (to avoid creating places in the car that are noisier due to addition rather  than cancellation due to the standing waves created).

 

There was an awful lot of work done on noise cancellation by Lotus et al in the late 1980's and early 1990's with some amazing results (the best being over 25dB of noise cancellation) but car manufacturers (with the exception of one limited edition model sold only in Japan) didn't want the additional cost. This work covered not only engine noise cancellation but also road noise cancellation and even engine vibration cancellation.

Edited 6 May, 2018 by SWBoy

[Chimble]

On 06/05/2018 at 09:37, norsko said:

The Vehicle noise cancellation is just a very fancy way to say that the Canton amp adjust volume according to vehicle speed. Something that has been in several cars and HU in 20 years.

I dont think that you "spend serious money" for the Canton system. You get four two way speaker system, a center speaker and a micro "subwoofer", plus a ten channel amp and active crossover. Try to buy that from an another serious car stereo manufacture and see what it will cost.

 

In my 2016 L&K its all about wheel noise. The engine are very quiet, no booming and very little wind noise.

You clearly don't know what you are talking about. We have a car with Canton and one without and there is a noticeable difference in cabin boom (road roar mainly).

Click this link if you are still in doubt: https://www.canton.de/en/skoda-en

 

[mrgf]

99p for a set of ear plugs!

 

Seriously though, The system that just turns up the volume as speed increases is old hat, not hi-tech! I have it in my 9 year old Fabia and I remember many years ago, they had it on Honda Goldwing motorcycles. I am talking eighties/nineties. 

[norsko]

1 hour ago, Chimble said:

You clearly don't know what you are talking about. We have a car with Canton and one without and there is a noticeable difference in cabin boom (road roar mainly).

Click this link if you are still in doubt: https://www.canton.de/en/skoda-en

 

I do think I know. You can unplug the amp, remove he fuse or do what ever you want - it want make any difference in noise.

I do have the Workshop manual with electric diagrams for the Canton system, and they cant make any active noise cancelation without several mics.

I have worked with room acoustic and tested several system that work with the same principals in home theater setups, and as soon you have tried to measure sound with a mic you discover how difficult this is.

If it hasnt been that difficult I am pretty sure all the premium car makers had this in more expensive cars several years ago.

 

There ARE differences in car boom and noise between different Octavias, thats for sure. But no one has been able to conclude what the difference is, why some cars has cabin boom and some dont.

[Guest]

1 hour ago, Chimble said:

You clearly don't know what you are talking about. We have a car with Canton and one without and there is a noticeable difference in cabin boom (road roar mainly).

Click this link if you are still in doubt: https://www.canton.de/en/skoda-en

 

 

Just looking at that Canton promotion - I really wouldn't use that as an example of how the system works because it's only sales gumph aimed at those who don't question.

 

Nonsense #1:  It states "Each car is different" and that their Canton systems are setup for the specific car. Then you look at the specs...  3 very different cars - Karoq, Kodiaq and Octavia (both hatch and estate remember) yet the system specs are exactly the same. So much for individuality then.

Nonsense #2: Doesn't matter where you sit in the car, you can enjoy blah, blah, blah.  But in the above mentioned cars, you have tweeters and midrange in the front, tweeters and woofers in the rear? In other words, for those in the rear, mid-range is going to be drowned out.

Nonsense #3: The upgrade costs around £500.  £500 for an amplifier, sound processor, differnet speakers, sub-woofer? No doubt it's better than the standard system but as for the claims made by Skoda marketing dept? I'd be asking exactly the same question as the OP - how does the noise cancelling system work?

 

 

Edited 7 May, 2018 by Guest

[shyVRS245]

Estates are always noisier than hatchbacks and hatchbacks are noisier than saloons, which is why Mercedes S class, BMW 7 series and Audi 8 are all saloons because manufacturers want the best base for their quiet limo's to impress wealthy clients who insist on quiet cabins. SIMPLE really.

[Gerrycan]

Maybe but I really do not think there is that much difference between the Octavia liftback and combi.

There may even be an argument for the combi being the quieter of the two but other factors seem to have more affect on individual vehicles than type. 

[Chimble]

10 hours ago, Scot5 said:

 

Just looking at that Canton promotion - I really wouldn't use that as an example of how the system works because it's only sales gumph aimed at those who don't question.

 

Nonsense #1:  It states "Each car is different" and that their Canton systems are setup for the specific car. Then you look at the specs...  3 very different cars - Karoq, Kodiaq and Octavia (both hatch and estate remember) yet the system specs are exactly the same. So much for individuality then.

Nonsense #2: Doesn't matter where you sit in the car, you can enjoy blah, blah, blah.  But in the above mentioned cars, you have tweeters and midrange in the front, tweeters and woofers in the rear? In other words, for those in the rear, mid-range is going to be drowned out.

Nonsense #3: The upgrade costs around £500.  £500 for an amplifier, sound processor, differnet speakers, sub-woofer? No doubt it's better than the standard system but as for the claims made by Skoda marketing dept? I'd be asking exactly the same question as the OP - how does the noise cancelling system work?

 

 

So because you don't know how they acheive it, Canton are just lying. 

[shyVRS245]

21 minutes ago, Gerrycan said:

Maybe but I really do not think there is that much difference between the Octavia liftback and combi.

There may even be an argument for the combi being the quieter of the two but other factors seem to have more affect on individual vehicles than type. 

It's due to better aerodynamics as well as sound deadening materials. In World Touring Car racing the Audi RS3 saloon is penalised by carrying 10kg extra ballast because it's body shape gives it an advantage as speeds increase compared to the Leons, Golfs, Civics etc.

As the air rushes off the back of an estate there is a vortex effect which is why they are both noisier than a hatchback but also get dirtier when driven in the rain on a motorway. Estates also tend to have flimsy roller blind type parcel shelves whereas hatchbacks tend to have more solid thicker parcel shelves which help with silencing the rear suspension noises . Saloons tend to have bulkheads which give better rigidity and therefore less creaks and other associated rattles that more open designs suffer from. This is why S class type vehicles are not made in estate bodies, too many issues with noise suppression.

[pist0nbr0ke]

2 hours ago, shyVRS245 said:

This is why S class type vehicles are not made in estate bodies, too many issues with noise suppression.

 

Ermm, could also be due to the fact that nobody would want/buy one? Limo type cars aren't normally estates. "Home James, and don't spare the horses, but please spare the labrador in the boot..." 

 

Although the Sultan of Brunei reportedly has commissioned one off estate versions of various Bentleys/Ferraris etc., and a UK Tesla owner has had a Model S converted to an estate...

[brettikivi]

16 hours ago, Scot5 said:

 

Just looking at that Canton promotion - I really wouldn't use that as an example of how the system works because it's only sales gumph aimed at those who don't question.

 

Nonsense #1:  It states "Each car is different" and that their Canton systems are setup for the specific car. Then you look at the specs...  3 very different cars - Karoq, Kodiaq and Octavia (both hatch and estate remember) yet the system specs are exactly the same. So much for individuality then.

Nonsense #2: Doesn't matter where you sit in the car, you can enjoy blah, blah, blah.  But in the above mentioned cars, you have tweeters and midrange in the front, tweeters and woofers in the rear? In other words, for those in the rear, mid-range is going to be drowned out.

Nonsense #3: The upgrade costs around £500.  £500 for an amplifier, sound processor, differnet speakers, sub-woofer? No doubt it's better than the standard system but as for the claims made by Skoda marketing dept? I'd be asking exactly the same question as the OP - how does the noise cancelling system work?

 

 

a decent DSP with 6 in and 8 out is - at a retail price for end-users - €200. 

Any decent system worth its salt will use mid woofers only down to around 50-60Hz anyway, so as to protect them at high levels. This is one of the things the GALA system does in the Octy - it turns the bass down so that when the volume is turned up as speed increases, the bass will not overwhelm those poor 6.5" drivers in the doors. There's nothing saying how the subs are tuned, whether they're sealed, passive or different specs for each door and there's no way to find that out with taking them apart. A different coil setup, suspension rigidity or woofer material will make a difference. That said, there's not that much fundamentally different between the four in terms of the longest dimension (important for cabin gain) or the actual volume of the cabin, or in terms of the seating position relative to any of the drivers.

 

A decently-done DSP really can fudge the imaging so that it's acceptable in most seats in the car, that's why even the base system in a 2016 has the option of "driver only" or all passengers for sound optimization.

 

If you were to pre-record and invert road noise at, say, 80km/h, you could convolute nicely or create an average filter to do this and the DSPs of today can interpolate. It's not rocket science. It *is* hard to do well IMO. 

 

 - Bret

[SWBoy]

12 minutes ago, brettikivi said:

It's not rocket science. It *is* hard to do well IMO.

Second that, good results were being achieved in the 1980s/1990s using a TI 320 series DSP - which is mind numbingly low performance compared to DSPs available in 2018.

[BOD20]

43 minutes ago, brettikivi said:

If you were to pre-record and invert road noise at, say, 80km/h, you could convolute nicely or create an average filter to do this and the DSPs of today can interpolate.

 

Interesting.... it would be perfectly feasible to "record" the noise made by a pre-production sample car at a range of speeds and road conditions. That would create a kind of template for the average noise generated by that car. The DSP could then use that template to dynamically adjust the EQ of sound played back through the speakers to minimise the effects of that noise. It would be a compromise, of course. But no microphones would be required in the production vehicles to achieve this.

 

I'm not suggesting that's what they have done - but it is quite possible.

[SWBoy]

49 minutes ago, BOD20 said:

 

Interesting.... it would be perfectly feasible to "record" the noise made by a pre-production sample car at a range of speeds and road conditions. That would create a kind of template for the average noise generated by that car. The DSP could then use that template to dynamically adjust the EQ of sound played back through the speakers to minimise the effects of that noise. It would be a compromise, of course. But no microphones would be required in the production vehicles to achieve this.

 

I'm not suggesting that's what they have done - but it is quite possible.

That would be noise masking not noise cancellation, since the noise would still be there - it's just that the audio system would be adjusting its frequency response to make the music/speech/WHY audible above the noise.

[brettikivi]

... with the follow-on problem being you need enough headroom (amplifier power, x-max of the drivers, so their ability to shift air, especially at bass frequencies) within the system to be able to play over the top of the road noise and then the sounds you actually want to hear. So how effective it actually is is another story, but it's quite possible that you could achieve significant improvements with a little effort. Halving road noise would be probably doable, I'd expect 10-15dB to be possible with a little effort.  Personally, I'd probably want to record multiple channels of road noise at different speaker driver locations and then convolute those simultaneously - one recording inverted per channel - that might be doable. It's something I'd like to play with given time and a little money. Inversion and convolution are two key things here, but how much effort needs to be put in and for what reward? That's another question entirely. Doing it "because I can" is probably the best reasoning

 

 - Bret

 

 

[Gerrycan]

10-15 dB reduction would be massive and I'm dubious that level is possible. Most manufacturers are happy if they can achieve 1 or 2 dB (which is quite a lot in energy values).

Mazda are a very popular brand in Australia but the one criticism often levelled at them is their high levels of NVH. Every new release or update of the Mazda 3 is always accompanied by claims of improvements in NVH that if true and added up would make the present day interior equivalent to an anechoic chamber....and it is patently not, There is a perceptible difference between the first and most recent models but we are 'only' talking about a couple of dB.

 

I have travelled a lot by air and always carry a pair of the cheapest noise reduction equipped ear-buds I can find for on-board use.

There is always a very high background ambient noise on commercial jet aircraft from the engines, air-conditioning and air-flow that merge into a homogenous roar, Inserting well fitting earbuds cuts it down a bit but it is when I activate the noise reduction that the noise at all frequencies reduces to acceptable levels. Probably good for 5dB reduction. Means you can listen to the entertainment in greater clarity and at much lower volumes.

 

If Canton did have true noise cancellation fitted that worked I don't think they could resist the temptation to have an on/off capability to show how clever and effective their technology was.

 

Finally, I drive a manual 1.4tsi which is a very quiet engine inside the car. The other day I accidently had the volume of the radio up too loud in stop/start traffic (orchestral piece with a wide dynamic volume range) and realised I was over-revving the engine for easing forward because I could not hear the engine over the music. I could drive by the rev counter but you really should not have to cope with that possible distraction in heavy traffic environment. If noise suppression included the engine then I would have difficulties. Not a problem for those with auto boxes of course. 

Edited 9 May, 2018 by Gerrycan

[SWBoy]

13 hours ago, brettikivi said:

 

 

 

8 hours ago, Gerrycan said:

10-15 dB reduction would be massive and I'm dubious that level is possible.

Nearly 30 years ago a UK automotive consultancy was achieving noise reduction of between 10 and 25dB using noise cancellation. That's the big plus of noise cancellation over traditional "add more sound damping materials" - it gives much bigger reductions without the penalty of significant weight gain.

Edited 9 May, 2018 by SWBoy

[SoupDragon]

With that order of noise cancellation, what happens if your wife wants to talk to you or the children in the back start complaining?

[shyVRS245]

30 minutes ago, SoupDragon said:

With that order of noise cancellation, what happens if your wife wants to talk to you or the children in the back start complaining?

Press the EJECTOR BUTTON!

[shyVRS245]

On ‎08‎/‎05‎/‎2018 at 11:54, pist0nbr0ke said:

 

Ermm, could also be due to the fact that nobody would want/buy one? Limo type cars aren't normally estates. "Home James, and don't spare the horses, but please spare the labrador in the boot..." 

 

Although the Sultan of Brunei reportedly has commissioned one off estate versions of various Bentleys/Ferraris etc., and a UK Tesla owner has had a Model S converted to an estate...

Try driving an estate, hatchback or saloon with the boot slightly open (say carrying something extremely long that sticks out the back) and see how loud they all are.

[pist0nbr0ke]

3 hours ago, shyVRS245 said:

Try driving an estate, hatchback or saloon with the boot slightly open (say carrying something extremely long that sticks out the back) and see how loud they all are.

 

Don't tell me the only reason they aren't estates is because they're louder 

[SoupDragon]

My question was serious, would not active noise cancellation null out noises that you need to hear?

[andyh41]

9 hours ago, SoupDragon said:

My question was serious, would not active noise cancellation null out noises that you need to hear?

 

I imagine the method is designed to target noise that is fairly continuous in duration and frequency, ie the constant drone of road or wind noise. Talking is rapidly varying in pitch, duration etc, so wouldn't be affected.