2015 YUKON NOISE IN CABIN

[The Zip]

Tobtek – 20sierra14 validates the research I have been conducting (based on the Enhanced Sound thread). My goal was to locate and silence the mics; I located them and provided the dealer with info what I wanted done. But on the Chevy SUVs (Tahoe/Suburban), the mics are under the headliner. The dealer was not sold enough on the Enhanced Sound to take down the headliner and the headliner takedown was more than I wanted to tackle. So I was at a stand-still. But now with 20sierra14 post, it seems that on the GMC SUVs (Yukon/Denali), the mics are outside of the headliner which will make my research feasible with the GMC platforms.

 

Also Tobtek based on my research, I was going to send you the following private message: “The research I conducted was to locate all of the mics in these vehicles and I did (4 mics to include Bluetooth). I would have silenced the mics myself, but it involved taking down the “headliner”, something a bit too busy for me to handle (headliner removal will require removal of panels, weather stripping, assist handles, dome light cover, etc). That’s where contacting you come in, someone who is about to have this done and a person familiar with the problem. If the dealer is about to take down your headliner, this time it may provide valuable information. Ask the dealer to disconnect the mics (don’t include Bluetooth) and call you for a test drive before they put it back together. If it doesn’t work, no harm no foul. They just reconnect the mics and replace the headliner. But without the mics, noise cancelling/enhancement doesn’t activate. I believe this is the only cost effective thing GM can do, take down the headliner and disconnect the mics. A manufacturer knows the answer to the problem, but GM is not the one, it’s Bose. Everything GM does is just lip service, and they will not be able to fix the problem unless they employ acousticians on the staff. Going to dealerships is a pre-condition to getting rid of your vehicle, not a fix to the problem. GM can live with the low number of returned vehicles, just as long as owners live with the buffeting issue”.

 

But now we know the mics, at least on the GMC platforms, are outside the headliner.

 

Mic names and locations: Radio Volume Compensator Interior Noise Microphone - right front passenger door assist handle / Radio Volume Compensator Interior Noise Microphone - rear compartment in front of the last dome light / Cellular Phone Microphone – driver side above the sunvisor / Radio Volume Compensator Interior Noise Microphone - left front driver assist handle.

 

Additionally, fuse 48 on the passenger compartment fuse box primarily manages the Amp, mics listed above, some tweeters/speakers, and also engine compartment noise cancellation, have not researched if a mic exists in the engine bay since I wasn’t experiencing V8 to V4 buffeting.

 

There was a primary method I was going to try if I had access to the mics. If anyone that has access to the mics want me to provide what I was going to do, send me a PM. My research and mitigation technique may not help me (at least right now), but it may help you.

Edited January 5, 2015 by The Zip

[Wrench589]

 

Mic names and locations: Radio Volume Compensator Interior Noise Microphone - right front passenger door assist handle / Radio Volume Compensator Interior Noise Microphone - rear compartment in front of the last dome light / Cellular Phone Microphone – driver side above the sunvisor / Radio Volume Compensator Interior Noise Microphone - left front driver assist handle.

 

Additionally, fuse 48 on the passenger compartment fuse box primarily manages the Amp, mics listed above, some tweeters/speakers, and also engine compartment noise cancellation, have not researched if a mic exists in the engine bay since I wasn’t experiencing V8 to V4 buffeting.

Where did you get the info on which mic does what? Just curious.

 

Yes, fuse 48 was one of the three I pulled earlier today. I like the idea of de-energizing the entire system instead of simply disabling the microphone because we really don't know how the active noise cancelling system works in total. It's an assumption that it is simply a feedback based system where sound is generated in response to sound detected by the microphones. But, according to the Enhanced Sound thread, the engine noise cancelling portion sounds to me like a feed-forward design, where the sounds generated are pre-programmed based on GM research data and simply play when certain engine speeds are occurring. To be honest, I can see why they would do that because noise cancelling based on measured sounds really only works for sound that is fairly constant in frequency and amplitude. Rapidly changing sounds can't be measured and cancelled fast enough and engine noise often varies tremendously.

 

So, to me, turning the whole bloody thing off and driving the vehicle is a good place to start. If anyone else is interested in trying that and letting us know, would be great.

[20Sierra14]

Tobtek – 20sierra14 validates the research I have been conducting (based on the Enhanced Sound thread). My goal was to locate and silence the mics; I located them and provided the dealer with info what I wanted done. But on the Chevy SUVs (Tahoe/Suburban), the mics are under the headliner. The dealer was not sold enough on the Enhanced Sound to take down the headliner and the headliner takedown was more than I wanted to tackle. So I was at a stand-still. But now with 20sierra14 post, it seems that on the GMC SUVs (Yukon/Denali), the mics are outside of the headliner which will make my research feasible with the GMC platforms.

 

Also Tobtek based on my research, I was going to send you the following private message: “The research I conducted was to locate all of the mics in these vehicles and I did (4 mics to include Bluetooth). I would have silenced the mics myself, but it involved taking down the “headliner”, something a bit too busy for me to handle (headliner removal will require removal of panels, weather stripping, assist handles, dome light cover, etc). That’s where contacting you come in, someone who is about to have this done and a person familiar with the problem. If the dealer is about to take down your headliner, this time it may provide valuable information. Ask the dealer to disconnect the mics (don’t include Bluetooth) and call you for a test drive before they put it back together. If it doesn’t work, no harm no foul. They just reconnect the mics and replace the headliner. But without the mics, noise cancelling/enhancement doesn’t activate. I believe this is the only cost effective thing GM can do, take down the headliner and disconnect the mics. A manufacturer knows the answer to the problem, but GM is not the one, it’s Bose. Everything GM does is just lip service, and they will not be able to fix the problem unless they employ acousticians on the staff. Going to dealerships is a pre-condition to getting rid of your vehicle, not a fix to the problem. GM can live with the low number of returned vehicles, just as long as owners live with the buffeting issue”.

 

But now we know the mics, at least on the GMC platforms, are outside the headliner.

 

Mic names and locations: Radio Volume Compensator Interior Noise Microphone - right front passenger door assist handle / Radio Volume Compensator Interior Noise Microphone - rear compartment in front of the last dome light / Cellular Phone Microphone – driver side above the sunvisor / Radio Volume Compensator Interior Noise Microphone - left front driver assist handle.

 

Additionally, fuse 48 on the passenger compartment fuse box primarily manages the Amp, mics listed above, some tweeters/speakers, and also engine compartment noise cancellation, have not researched if a mic exists in the engine bay since I wasn’t experiencing V8 to V4 buffeting.

 

There was a primary method I was going to try if I had access to the mics. If anyone that has access to the mics want me to provide what I was going to do, send me a PM. My research and mitigation technique may not help me (at least right now), but it may help you.

 

 

Since the lower models (SLE, SLT, LT and even LTZ) essentially hide the mics; whereas the models w/ the 6.2 motor and "noise cancelation" vehicles exposes them, would bring a new fact that anyone w/ the lower models could not find the microphone locations -- Great info!

 

To keep it simple, without the fancy words, the CPU for the Noise Canceling needs preprogramed... Problem solved???

[PokerMunkee]

Good stuff. Looks like you guys are narrowing this issue to the ANC. Hopefully GM Engineers are watching this thread and will have a solution for everyone. Sounds like this has cost them millions already in buy backs and warranty repairs! (well, probably not...they are reselling the buy backs)

Edited January 5, 2015 by PokerMunkee

[Anon2015]

 

Kind of; but, not entirely...on the other hand, very costly. At the end of the day, among the problems with ANC in a vehicle are the seating. On the bright side, the seats pretty much stay where the are at. On the downside, all the ears are not in the same place. When you have ANC headphones, the ears stay in the same location (always) with respect to relationships between the ears, the speakers, and the microphones. For ANC to work well, the sound you're trying to cancel and the sound you're generating to provide the cancellation must be at exactly 180 phase and the same amplitude. That is reasonably easy to accomplish for one seating location. For one reason or another, Tahoes and Yukons have more than one seating location. The compromise in this case is to only attempt ANC for frequencies with rather long wave lengths...for a Yukon/Tahoe you'd likely not want to attempt anything above about 35-40Hz .... if you do, you very well can have pulsing.

 

The above is a traditional means of ANC as you'd find in noise cancellation headsets. Another method (as alluded to by ZIP) is to attempt to cancel the offending noise much closer to the source (if not at the source). The can be, and has been done in industrial and other applications; however, for this to be effective (without pulsing) the source of the cancelling signal needs to be very, very close to the source of the undesired signal. This is very much the case when the sound events are in an enclosed (fully or partially) space.

 

In my mind, should ANC be the cause of this annoyance, the fix is relatively easy and inexpensive to resolve. Simply install a software update that would allow one to turn off ANC in the settings menu for the vehicle. That would be effective for now while GM engages outside parties to resolve the problem and provide a software fix for current vehicles and a physical fix for future vehicles. That, of course, is suggesting a simply solution to what could very likely be a very complex problem without a 'simple' solution.

 

Unfortunately, GM has raised the ire of their affected customers by a failure to communicate..."yes, we understand some of our customers are affected, and we are working toward a solution" rather than "we've never heard of that problem before".

[Anon2015]

"Radio Volume Compensator Interior Noise Microphone"

Note you may want to get some additional information about the actual function of microphones so denoted. If your vehicle has Bose AudioPilot (worthless in its current manifestation except for marketing who-ha), these microphones may be used for ANC, AudioPilot, or both. Just a heads up.

[Wrench589]

Still not 100% clear on how Audiopilot is supposed to work. It adjusts the output volume/equalization of the music to essentially counteract background noise? Instead of a simple adjustment of the total volume based on speed alone?

 

I gotta say that I can't hear any difference with it on or off. The old "SCV" (speed compensated volume) in my 2005 Sierra and in my two current Ford trucks is 1000 X better then Audiopilot!

 

But I digress from the topic at hand. Unless Audiopilot is also playing a role in this. Don't think so, since I can't hear any difference with it on or off. But at this point, I'm open to every and all possibilities!

[Wrench589]

Kind of; but, not entirely...on the other hand, very costly. At the end of the day, among the problems with ANC in a vehicle are the seating. On the bright side, the seats pretty much stay where the are at. On the downside, all the ears are not in the same place. When you have ANC headphones, the ears stay in the same location (always) with respect to relationships between the ears, the speakers, and the microphones. For ANC to work well, the sound you're trying to cancel and the sound you're generating to provide the cancellation must be at exactly 180 phase and the same amplitude. That is reasonably easy to accomplish for one seating location. For one reason or another, Tahoes and Yukons have more than one seating location. The compromise in this case is to only attempt ANC for frequencies with rather long wave lengths...for a Yukon/Tahoe you'd likely not want to attempt anything above about 35-40Hz .... if you do, you very well can have pulsing.

 

Very, very interesting. My wife says that she cannon hear the buffeting from the passenger seat, even though I can hear it in the drivers seat. And, she hears it from the drivers seat. So, completely consistent with what you are saying. Heads up for anyone taking someone from the dealership for a ride and having trouble getting them to recognize the problem! If they are in the passenger seat, they actually may not be hearing it!!

 

To me, makes no fricken' sense to cancel the low frequency noise. I've never driven a vehicle that I thought the low frequency noise needs to be addressed - until the 2015 Yukon came along! To me, the higher frequency "wind noise" is more of an issue in general, which is why noise cancelling headphones are so great on an airplane. And if cancelling higher frequencies is not practical with vehicle sound system for the reasons you've mentioned, then the whole "ANC" is a waste of time and money!

[20Sierra14]

The big question is... What would be the next best step to take to have GM consider the ANC system for a fix??? The GM reps say they monitor this thread, but seem to have fallen silent

 

TOBTEK -- I'm anxious to hear if you were able to stop the dealer from distorting your Escalade -- and were you abe to speak to your local field engineer???

[Anon2015]

"Still not 100% clear on how Audiopilot is supposed to work."

To understand the thinking behind AudioPilot requires some background information. The quietest sound recorded on a sound track (movie or music) is at 22dB...the loudest at 105dB (low bass is 115dB). Your dynamic range is then from 22dB to 105dB. Among the many metrics of a good sound reproduction system is the ability to reproduce the entire dynamic range. The issue is 22dB is very, very quiet. If you're in a proper sound playback room with a noise floor of say 20dB, it is so quiet, you can hear your heart beat. A very quiet room in a home has a noise floor of 33dB to 35dB (that is typical design standard for a library). So, if you're watching a movie or listening to music in your quiet listening room with a noise floor of 35dB, all the sound from 22dB to 34dB is masked...you cannot hear it. It doesn't exist. If the character on the screen is whispering, you cannot hear or understand what is being said. Solution...turn up the volume! Yeah!

 

That's not such a good plan. Decibels are logs ... not linear. To overcome the noise floor in your very quiet home, you've just increased the volume by a factor of 6 to 8 times. Not a problem for those quiet passages. What you have done however is made normal dialog and the loudest passages also 6 to 8 times louder! Normal dialog isn't talking, it is yelling. The loudest passages are (yes they are!) loud enough to cause temporary hearing loss and in some cases long term hearing loss not to mention burning out drivers in your speakers and clipping your amplifiers. Basically speed compensated volume is raising the volume to save you the trouble of doing it yourself.

 

The concept behind AudioPilot is to first determine which frequency band(s) are masking the playback in your car. The sunroof open will create a different set of frequencies than driving over cobble stones. What AudioPilot then attempts to do is increase the volume of only those frequencies which are being overwhelmed by driving/traffic noise. (There are some psychoacoustic 'things' going on as well.)

 

Convinced it wasn't working, I contacted Bose. The marketing person said...oh, yeah. You won't notice it's working unless you're listening for it; but, it will easily compensate for having a window or the sunroof open. (My experience in three AudioPilot equipped cars ... boulderdash.) When I explained I tested it and it didn't appear to work, I was transferred to a 'technical product manager' who said the best way to test AudioPilot was:

1. Start the car and with all the doors and windows closed;

2. Tune to a talk radio station or play a CD with voices talking;

3. Manually turn down the volume control to where you can just barely hear the talking;

5. Start driving (freeway preferred) and as the noise inside the cabin gets louder you will still hear the voices;

6. Turn off AudioPilot ... voices go away (voices in your head also go away with a few fine single malts as well);

7. Turn on AudioPilot...voices are back...open the window, you still hear the voices.

 

So, I did that test. At 20-30 miles per hour I (a trained listener) could hear a very subtle increase in the voices. Beyond that speed, no way. Window or Sunroof open...no bloody way. In my original testing, I measured the voltage to two of the speakers in the car ... then increased the sound in the car with band limited pink noise for multiple bands over the audible range. No measurable increase in voltages. I guess I need a more sensitive voltmeter.

 

In any event, AudioPilot is an interesting concept and a better approach than SCV; but, as implemented currently, it is a fail IMHO.

Edited January 6, 2015 by Anon2015

[bamamike]

Glad I found this site, I thought I was crazy. When we test drove the Yukon XL I noticed this sound and or feel. I mentioned it too the salesman and described it as a balance or tire issue. He said it was probably because the tires were cold and flat spotted. It made sense and we bought the vehicle but the problem didn't quit. I took it back and they rotated the tires and road forced balanced, they said the tires were out of balance. Once again the sound/feel didn't quit. I took it back again and they road forced balanced the tires saying one was out. Once again the sound/feel was the same. I drove several others(with different tire rim combos) on the lot with the service manager and experienced the same thing on all the yukons and denali's. The service manager claims he doesn't here or feel anything but also mentioned the exhaust change over when it kicks into 4 cylinders and said maybe that's what your hearing or feeling.

 

I drove a friends with different tires and rims and it sounds and feels the same. I was about to take it back this week and ask that they put Michelin tires on the Yukon versus these continentals then I found this board. I just emailed a link to myy dealer and ask that they review this website. We have a great locally owned dealership Ray Miller Buick/GMC here and feel confident they will fix this issue. We like the yukon xl but cannot continue to drive it under these conditions.

 

I think someone accurately described it as when someone rolls one window down going 55mph its the noise and feel you get from this happening. GM really touted eliminating road noise and it's true they did it's very quiet. I just got back from a 7 hour trip each way driving a friends 6 year old denali in which I drove their car. I could hear wind and road noise like crazy and when I got home we drove ours and there was none of those outside noises but the boom was back. My wife had gotten use to driving it but when we got back she couldn't believe how bad it was until now. It's so bad I don't even want to drive it anywhere.

 

I will keep you guys updated on what we find out.

[Anon2015]

Bamamike... for the record Go Dawgs!

[Wrench589]

Anon2015, thanks for the excellent explanation. More or less what I was thinking but you've described it well. Like you, I don't hear any difference on or off, but I will do the test as Bose suggested and see what I get.

 

I gotta say, it must be extremely complicated to keep all those compensation algorithms from fighting each other - Engine Sound Compensation, Active Noise Compensation and Audiopilot. I'm starting to question if it is even theoretically possible, never might practically possible!

 

OK, I have an update of sorts. Had a chance to drive it tonight for the first time since I removed the fuses and drove it per my post Sunday. Now, my wife has been running the kids around yesterday and today, so it has been stopped and started and driven a fair bit since I put the fuses back in. But tonight, I drove it. Drove to town, about 20 km, and I was astounded that it seemed that the buffeting was gone! I was estatic. Now, I could still hear some "booming" over any bumps, but same as I observed Sunday with the fuse pulled. But no buffeting and no pressure sensation.

 

Parked for a couple of hours and then drove home. Seemed that the buffeting was back, but only at 80 kph. But the further we drive, the more it seemed to come back at all speeds.

 

Now, I still maintain that road conditions contribute greatly to this issue. Bumps and rough roads seem to make it worse. But, I observed something else tonight. Coming up to a turn, uphill, I leg off the throttle well I advance and the buffeting seemed to diminish completely even the vehicle speed was still high, as the engine rpm's dropped off. Not sure this is repeatable, so take it with a grain of salt. But may be a correlation to engine speed/load that I didn't see before.

 

One thing that comes to mind is if the system is doing any kind of adaptive learning, that pulling the fuses resets. I know the engine and powertrian controls on modern vehicle have numerous adaptive parameters that get continuously adjusted as the vehicle is driven. But if the parameters are off, can throw the controller out of whack. Resetting will result in a properly running engine until the adaptations mess it up again. I've lived through this on a BMW and believe me, it was a nightmare to diagnose but once I found it, fixed that faulting valve, the car runs perfect! It would not surprise me if Bose has programmed a similar feature in to make the feedback loops more effective and more feed-forward, as well as a means to compensate for variances in acoustics and responses vehicle to vehicle.

 

Just a follow up comment to bamamike's post, I was thinking about changing the tires on ours. We've got the 22" option and it's fitted with the Bridgestones. I've read some tire reviews on the Bridgestones and some folks are saying they are noisy and rough. And, folks are saying the Continentals are smooth and quiet. And since I'm convinced rough vibration contribiputes to the buffeting, I was thinking a tire change might be quite helpful. Wouldn't be the first time changing brands of tires solve a problem with a vehicle! But now I'm hearing the Continentals suck too. So that doesn't leave any decent options for the 22".

[20Sierra14]

 

OK, I have an update of sorts. Had a chance to drive it tonight for the first time since I removed the fuses and drove it per my post Sunday. Now, my wife has been running the kids around yesterday and today, so it has been stopped and started and driven a fair bit since I put the fuses back in. But tonight, I drove it. Drove to town, about 20 km, and I was astounded that it seemed that the buffeting was gone! I was estatic. Now, I could still hear some "booming" over any bumps, but same as I observed Sunday with the fuse pulled. But no buffeting and no pressure sensation.

 

Parked for a couple of hours and then drove home. Seemed that the buffeting was back, but only at 80 kph. But the further we drive, the more it seemed to come back at all speeds.

 

Now, I still maintain that road conditions contribute greatly to this issue. Bumps and rough roads seem to make it worse. But, I observed something else tonight. Coming up to a turn, uphill, I leg off the throttle well I advance and the buffeting seemed to diminish completely even the vehicle speed was still high, as the engine rpm's dropped off. Not sure this is repeatable, so take it with a grain of salt. But may be a correlation to engine speed/load that I didn't see before.

 

One thing that comes to mind is if the system is doing any kind of adaptive learning, that pulling the fuses resets. I know the engine and powertrian controls on modern vehicle have numerous adaptive parameters that get continuously adjusted as the vehicle is driven. But if the parameters are off, can throw the controller out of whack. Resetting will result in a properly running engine until the adaptations mess it up again. I've lived through this on a BMW and believe me, it was a nightmare to diagnose but once I found it, fixed that faulting valve, the car runs perfect! It would not surprise me if Bose has programmed a similar feature in to make the feedback loops more effective and more feed-forward, as well as a means to compensate for variances in acoustics and responses vehicle to vehicle.

 

 

 

 

Precisely the effect I had! I pulled the fuses and for almost a week the pressure was gone! I too, was excited!!

 

My wife drives the Yukon 90% of the time and I didn't get to spend any time in it until the past couple weeks during the holidays. During that time, the constant pressure came back -- and it hit hard this time! New Year's Eve was ruined for me because of the pressure I had while in the Yukon. I wore in-ear headphones the rest of the time I had to get in it. Over this past weekend, I did the "cotton ball" theory and the pressure was GONE once again!!

 

So, now we have noted 2 EXACT same experiences from different Yukons and different people... Another focus to the idea that there CANNOT be any other "thing" causing the pressure but the ANC!!

[Anon2015]

" Another focus to the idea that there CANNOT be any other "thing" causing the pressure but the ANC!!"

 

Caution Will Robinson ... ANC may be the symptom and not the root cause...but clearly a place to start.