Automatic Noise Cancellation Problem

[stevedebi]

Possible, I suppose, but that seems like an incredible (literally) stretch to me.

 

I think that it is more likely that only one set of amplifiers drives the speakers and that when the audio is off, those amplifiers are off and there will be no sound coming out of those speakers. It seems highly unlikely that two separate amplifiers would be driving the same speaker at the same time.  It also seems unlikely that the amplifiers would not be turned off with the audio system power, since they would be the principal power draw.

 

Maybe someone who actually knows will respond.

Jack,

The URL I provided states that it uses the audio system to produce the sounds that cancel out the noise. Is that not enough?

 

"The module instantaneously and continuously generates opposing sound waves. This reversed wave is directed through the Fusion Hybrid’s audio system, combining with the original engine noise wave to cancel out any potentially objectionable sound."

 

It seems obvious that they keep the amp and speakers active all the time. Maybe that accounts for some of that "other" energy I see on my left hand display, even when the HVAC is off.

Edited November 5, 2014 by stevedebi

[jdbob]

Possible, I suppose, but that seems like an incredible (literally) stretch to me.

 

I think that it is more likely that only one set of amplifiers drives the speakers and that when the audio is off, those amplifiers are off and there will be no sound coming out of those speakers. It seems highly unlikely that two separate amplifiers would be driving the same speaker at the same time.  It also seems unlikely that the amplifiers would not be turned off with the audio system power, since they would be the principal power draw.

 

Maybe someone who actually knows will respond.

 

I didn't say there were more than one set of amplifiers. I said that there are multiple modules that make up the audio system. Those other modules don't drive any speakers, they only provide a number of audio inputs (such as the audio inputs in the center console, radio, satellite radio, bluetooth audio, etc.) to the amplifiers.

[Smiling Jack]

Jack,

The URL I provided states that it uses the audio system to produce the sounds that cancel out the noise. Is that not enough?

 

"The module instantaneously and continuously generates opposing sound waves. This reversed wave is directed through the Fusion Hybrid’s audio system, combining with the original engine noise wave to cancel out any potentially objectionable sound."

 

It seems obvious that they keep the amp and speakers active all the time. Maybe that accounts for some of that "other" energy I see on my left hand display, even when the HVAC is off.

 

Could be, I suppose.

 

Once again, perhaps someone who actually knows will respond.

 

Otherwise I suppose there are a few ways we could test this out.

[fbov]

I see no reason to doubt the explanation provided. It's not a stretch to most audiophiles (or audiofools depending on your point of view); separate amp and pre-amp/source installations are especially common in car audio. .

 

Amps can have more than one input, and newer Class-D amps have very low standby current draw, so there's no reason not to leave them on. You'd just be shutting off one of multiple sources to the amp when turning off the radio. Can you use the phone when the radio's off? From an engineering standpoint, doing otherwise is poor practice, as there's nothing critical in this feature that would warrant redundant amps, with associated weight and cost.

 

HAve fun,

Frank

[wb8nbs]

Noise Cancellation?  Didn't know we had this?  Is that why when I drive with the windows down or a window down it makes that offensive reverberation rumbling sound?  Interesting.  ;)

Cars make a very low (like 1-5 hz) vibration when you open a window because you have effectively turned the whole  passenger compartment into a giant whistle. Usually goes away if you open a second window which spoils the resonance of the passenger compartment.

[wb8nbs]

The audio system is turned off, but the ANC isn't. Here is a pretty good explanation for the Fusion hybrid, from 2012.

 

http://corporate.ford.com/news-center/press-releases-detail/pr-2013-ford-fusion-hybrid2658-active-37160

 

The entire point of the system is that it is sending out noise that exactly cancels out the noise detected by the sensors - so you hear nothing.

 

That URL is broken unfortunately.

[bigalpha]

Cars make a very low (like 1-5 hz) vibration when you open a window because you have effectively turned the whole  passenger compartment into a giant whistle. Usually goes away if you open a second window which spoils the resonance of the passenger compartment.

 

And this car is particularly bad about the vibration. 

[wb8nbs]

 

 

 

My ANC does not like passengers in the front seat for the most part. It's my daily driver and only when family of lunch buddies get in the car, the low db noise happens. Quite painful to everyone's ears and very embarrassing. Some of my passengers even put their fingers into their ears and say, "...make it stop.". At first, it does sound like the engine at low rpm, but you can easily prove, that it is the ANC. When it happens, just reach up and start tapping one of the over head microphones. The front passenger microphone works the best. If you hold the throttle steady when the drone is heard, start tapping the mic, and the noise goes away. Quit tapping, it immediately comes back. The front driver's mic has to be tapped slightly harder, and the rear mic even harder. The focus appears to be on the front passenger area. As tapping is awkward, especially when looking forward while driving and feeling the ceiling for the mic, I choose to increase/decrease the throttle. The only times by myself, that I can hear the db noise start, but never reach the full drone stage, is in music on Sirius XM radio. It will sound as if you set a sub woofer to low in the db, then it begins to distort the song. I listen to 80s, Message, and Boneyard. It's the base guitar/keyboard, that brings it out.

 

 

Where exactly, are the three microphones located?

[62Lincoln]

Where exactly, are the three microphones located?

 

 

 In the headliner.

[Blue Tom]

That was one of the only things that a saleswoman pointed out on our first C-Max test drive.  My wife was commenting that it seemed kind of noisy on the highway.  The sales gal said "well, the typical response would be to turn up the radio and say, 'What noise?'"  Then she pointed out the microphones and explained the ANC, which I thought was pretty cool.  The audio happened to be off at that time during the test drive, FWIW.  But since we bought the car, I've actually noticed a lot less engine noise/vibration than I remember on that test drive.  Probably was just more sensitive at the time since we were looking for flaws.  I still think it's cool that they include it, but I can't help but think it was just an engineering requirement because they couldn't mechanically suppress it to acceptable NVH standards.  Some sports cars play artificial engine noises over the speakers because their cabins are so quiet.  The C-Max, with its tiny engine, does its best to eliminate the engine noise from the cabin.  Different strokes for different car buyers, it would seem.  Personally, I wouldn't mind an option to pipe in some sweet V8 burbles that are synced to the throttle. You know, for irony.  But that's just me.

[stevedebi]

... I still think it's cool that they include it, but I can't help but think it was just an engineering requirement because they couldn't mechanically suppress it to acceptable NVH standards.  Some sports cars play artificial engine noises over the speakers because their cabins are so quiet.  The C-Max, with its tiny engine, does its best to eliminate the engine noise from the cabin.  Different strokes for different car buyers, it would seem.  Personally, I wouldn't mind an option to pipe in some sweet V8 burbles that are synced to the throttle. You know, for irony.  But that's just me.

They could have mechanically supressed the engine noises - many manufacturers do. They chose to let the engine produce the noises, and cancel them instead. That way they could keep the engine both powerful and lighter, because it is less complex and has fewer parts.

Edited January 17, 2015 by stevedebi

[Smiling Jack]

FWIW:   From my experience yesterday:

 

1.  At highway speed with a rear window opened a few inches, there is very definitely (as others have posted) a loud, horrible, low-frequency, pulsing sound.

 

2. The sound is just as loud and horrible with the audio system off as with it on.

[stevedebi]

FWIW:   From my experience yesterday:

 

1.  At highway speed with a rear window opened a few inches, there is very definitely (as others have posted) a loud, horrible, low-frequency, pulsing sound.

 

2. The sound is just as loud and horrible with the audio system off as with it on.

That is normal and happens with all cars. If you crack open a front window and then the rear, it won't make the sound. You just cannot open only the rear windows in a hatchback, due to the air flow back there.

[Smiling Jack]

That is normal and happens with all cars. If you crack open a front window and then the rear, it won't make the sound. You just cannot open only the rear windows in a hatchback, due to the air flow back there.

 

 

To clarify:

 

I am familiar with the ordinary problem and the usual solutions.

 

The noise to which I refer is ten times worse, and it seems to come from the speakers, and it seems plausible that it is from the noise cancellation system - as other have posted.

 

The point of my post was to confirm that I had experienced the thing that others had posted about and to relay my observation that it did not quit when the sound system was turned off.

[stevedebi]

To clarify:

 

I am familiar with the ordinary problem and the usual solutions.

 

The noise to which I refer is ten times worse, and it seems to come from the speakers, and it seems plausible that it is from the noise cancellation system - as other have posted.

 

The point of my post was to confirm that I had experienced the thing that others had posted about and to relay my observation that it did not quit when the sound system was turned off.

Ah, sorry. I thought you may not have known. I suspect the noise supression wasn't programmed for that. Room for improvement.

[DaveofDurham]

Apparently some vehicles, including some Ford's,  have noise making as part of their noise cancellation system.

America’s best-selling cars and trucks are built on lies: The rise of fake engine noise

http://wapo.st/1yrDUbO

[Smiling Jack]

Apparently some vehicles, including some Ford's,  have noise making as part of their noise cancellation system.

America’s best-selling cars and trucks are built on lies: The rise of fake engine noise

http://wapo.st/1yrDUbO

 

Apparently some vehicles, including some Ford's,  have noise making as part of their noise cancellation system.

America’s best-selling cars and trucks are built on lies: The rise of fake engine noise

http://wapo.st/1yrDUbO

 

Many thanks to Dave for posting this.

 

What an education !  Everyone should read the link.

 

I would favor a swith so that the driver could turn such stuff on or off according to preference and situation  (as we do now have with most traction control systems).

[jdbob]

In our cars the idea is to reduce the engine noise in the cabin, I'm OK with that.

[fbov]

They could have mechanically supressed the engine noises - many manufacturers do. They chose to let the engine produce the noises, and cancel them instead. That way they could keep the engine both powerful and lighter, because it is less complex and has fewer parts.

I'd wager the car has lots of mechanical noise suppression...

 

Remember that quiet interiors have been a selling point of luxury cars for decades. Seems highly rational to use a belt-and-suspenders approach once new technologies, like electronic noise supression become available. In fact, in noise suppression that's the only way to do it.

 

As to the noise produced with one window open, blame aerodynamics for giving the rear windows smooth air flow. You're just blowing a large whistle, with you inside.

 

Have fun,

Frank

[stevedebi]

I'd wager the car has lots of mechanical noise suppression...

 

Remember that quiet interiors have been a selling point of luxury cars for decades. Seems highly rational to use a belt-and-suspenders approach once new technologies, like electronic noise supression become available. In fact, in noise suppression that's the only way to do it.

 

As to the noise produced with one window open, blame aerodynamics for giving the rear windows smooth air flow. You're just blowing a large whistle, with you inside.

 

Have fun,

Frank

I recall that the ANS system description mentioned that they reduced engine weight by allowing it to be louder. Not that I can recall the URL, of course...

[Chuckee]

My active noise cancellation in my 2017 C-Max stops working when the cabin temperature rises above 100 degree F.  It will not come back on until the temperature drops back to below 90 degrees F. and the ignition switch is cycled off and then on.

 

Dealer looked at it and said no codes were found but the cabin was not hot the day they looked at it.  I just found out about the "temperature thing" today.

[Chuckee]

On the reply about how good the noise suppression is on the C-Max and the ANC may not be needed.  I have recordings that show there is a big difference when the ANC is not operating,  especially with engine noise and road noise at 65 mph.

[homestead]

2 hours ago, Chuckee said:

My active noise cancellation in my 2017 C-Max stops working when the cabin temperature rises above 100 degree F.  It will not come back on until the temperature drops back to below 90 degrees F. and the ignition switch is cycled off and then on.

 

Dealer looked at it and said no codes were found but the cabin was not hot the day they looked at it.  I just found out about the "temperature thing" today.

Wow, do you drive the car when the cabin is 90-100?  Does the AC function?

Our radio died when we had a heat wave 110+ outside.  Once the temps came down the radio started working again.