Yes I know this for a fact and have worked on various algorithms for that m=
arket.=20
Yes the anti-noise is on all the time. It's mostly effective below 200hz or=
 so.=20
The most common approach synthesizes sine waves based on tachometer pulses =
and adjusts the amplitude and phase of each harmonic to achieve a null. The=
re are one or more error microphones in the roof liner to generate an error=
 signal that drives the additive algorithm.=20

More advanced algorithms use a signal from an accelerometer mounted in the =
engine compartment as the reference signal, and use some form of the FXLMS =
algorithm to generate the anti-noise.=20

There are many real-world complications, and everyone who naively ventures =
into this area is pretty humble after a year or so of trying to achieve goo=
d results.=20

Bob

On 4/24/2016 7:07 AM, radams2000@gmail.com wrote:
> The marketing department may have mangled the language, but generating anti-noise through the audio speakers is now common , even in low-end cars. It allows them to remove a lot of heavy sound-dampening materials, so they get slightly better mpg (and it's cheaper, the speakers are already there, you just need to add DSP mips ).
> Personally I'm uncomfortable knowing that if I cut my speaker wires, my car will sound like a tin can.

How much of this do you know for a fact?  So the car stereo is on all 
the time the engine is running?  Or turning off the stereo makes your 
vehicle noisy?

-- 

Rick

On Sun, 24 Apr 2016 04:07:43 -0700 (PDT), radams2000@gmail.com wrote:

>The marketing department may have mangled the language, but generating anti=
>-noise through the audio speakers is now common , even in low-end cars. It =
>allows them to remove a lot of heavy sound-dampening materials, so they get=
> slightly better mpg (and it's cheaper, the speakers are already there, you=
> just need to add DSP mips ).=20
>Personally I'm uncomfortable knowing that if I cut my speaker wires, my car=
> will sound like a tin can.=20
>
>Bob

But that's good for diagnostics.  You don't know if your brakes are
about to fail or the transmission about to fall out if you can't hear
the proper noises.

Race cars are like that.   We just had an event at a track that has
pretty tight sound restrictions, so everybody had to install mufflers,
etc.   All of a sudden people need tons of suspension or drivetrain
work because they could hear all the warning noises they couldn't hear
before.

I thought it was funny.  ;)

On 4/24/2016 6:07 AM, radams2000@gmail.com wrote:
> The marketing department may have mangled the language, but generating anti-noise through the audio speakers is now common , even in low-end cars. It allows them to remove a lot of heavy sound-dampening materials, so they get slightly better mpg (and it's cheaper, the speakers are already there, you just need to add DSP mips ).
> Personally I'm uncomfortable knowing that if I cut my speaker wires, my car will sound like a tin can.
>

I was sort-of aware of anti-noise. It was manner of mangling that 
hit my funny-bone.

The marketing department may have mangled the language, but generating anti-noise through the audio speakers is now common , even in low-end cars. It allows them to remove a lot of heavy sound-dampening materials, so they get slightly better mpg (and it's cheaper, the speakers are already there, you just need to add DSP mips ). 
Personally I'm uncomfortable knowing that if I cut my speaker wires, my car will sound like a tin can. 

Bob

On Friday, April 22, 2016 at 10:33:28 AM UTC-7, Richard Owlett wrote:
> On 4/22/2016 10:52 AM, Eric Jacobsen wrote:
> > On Thu, 21 Apr 2016 22:38:03 -0500, Richard Owlett
> > <ro> wrote:
> >
> >> GMC truck boasts "sound canceling frequency" ;/
> >> Caught the ad this morning, wasn't sure I'd heard correctly.
> >> Just saw it again. My ears had not deceived me.
> >
> > I suspect that's marketing-speak for ANC.
> 
> They called.it something-else elsewhere.
> 
> >
> > Sounds expensive.  ;)
> 
> I'm not an audiophile, but they were touting the brand of 
> microphones used so I suspect you're correct.
> 
> >
> >

Well if they make the AE (audiophile edition) of the truck, I hope it comes with oxygen free, silver platinum wiring and a record player mounted in the dash.

On 4/22/2016 10:52 AM, Eric Jacobsen wrote:
> On Thu, 21 Apr 2016 22:38:03 -0500, Richard Owlett
> <rowlett@cloud85.net> wrote:
>
>> GMC truck boasts "sound canceling frequency" ;/
>> Caught the ad this morning, wasn't sure I'd heard correctly.
>> Just saw it again. My ears had not deceived me.
>
> I suspect that's marketing-speak for ANC.

They called.it something-else elsewhere.

>
> Sounds expensive.  ;)

I'm not an audiophile, but they were touting the brand of 
microphones used so I suspect you're correct.

>
>

Richard Owlett wrote:
> GMC truck boasts "sound canceling frequency" ;/
> Caught the ad this morning, wasn't sure I'd heard correctly.
> Just saw it again. My ears had not deceived me.

Then there's this classic:
https://www.youtube.com/watch?v=egUqBH2V4rI

-- 
Les Cargill

On 22.04.2016 15:38, Greg Berchin wrote:
> On Thursday, April 21, 2016 at 10:38:07 PM UTC-5, Richard Owlett wrote:
>> GMC truck boasts "sound canceling frequency" ;
>
> That's to go along with their "light-canceling colors."
>

And their fire escape plans are just EXIT charts.

Gene

On Thu, 21 Apr 2016 22:38:03 -0500, Richard Owlett
<rowlett@cloud85.net> wrote:

>GMC truck boasts "sound canceling frequency" ;/
>Caught the ad this morning, wasn't sure I'd heard correctly.
>Just saw it again. My ears had not deceived me.

I suspect that's marketing-speak for ANC.

Sounds expensive.  ;)