2015 YUKON NOISE IN CABIN

[Anon2015]

Well, kind of and not kind of. Below what is known as Fs, or the Schroeder frequency, sound behavior in a enclosed space becomes modal. Modal behavior, in the most simple sense, means there are areas within a space which, for any given frequency, the sound peaks (is louder) or nulls (softer). Modal behavior would predict modal peaks in the center of the space...or near the second/third row of seats. That would explain the greater impact in that area.

 

As to the pressure. If we produce, say a 50Hz, sound in a room from a single source (a speaker), you can move around the room and hear areas where the sound is loud and areas where you can no longer hear the sound. Now, if we produce sound of the same frequency and loudness (sound PRESSURE level - SPL) but exactly 180 degrees out of phase, you will not hear the 50Hz noise. We detect sound as a change in pressure...if there is no change in pressure, we don't perceive sound. The 180 degree out of phase signal basically makes the pressure constant...there is no change in pressure, hence we do not perceive (or hear) sound. HOWEVER, we have now increased the air pressure in the room. That increase in air pressure is what you are feeling where active noise cancellation is in use ... if you are a pilot and use Noise Cancellation headsets (ala Bose A20), as soon as you turn them on, you feel a constant pressure in your ears.

 

So what's happening in these Yukons? I have no definitive clue. I haven't experienced it, haven't tested a truck with that problem, haven't hacked the Bose DSP to determine what they are doing (and I wouldn't anyway), and haven't had the results of testing to present for Medical review. (Although I do have significant experts in the field available to me.) More troubling to me is why this occurs in some trucks and not others...that would mean one would need two trucks to test and determine exactly where the differences are. That puts the burden clearly on GM and they appear to be either in denial or keeping the issue very close to the vest. I'm certainly not buying two Yukons!

 

20Sierra14 ... the circumstance with your wife is very serious. Either the truck is causing this or there is some other medical condition which needs immediate attention. In any case, the situation you described (accident) needs to be reported to both GM and NHTSA immediately. I truly hope your wife is OK and this is not some other medical issue.

 

EDIT:

-- This is assuming the ANC system is, in fact, the culprit and something else is not going on. GM is not the only automobile manufacturer using ANC! This implementation may be the problem, may be contributory to the problem, or be totally unrelated to the problem.

-- Turn off ANC. In what they give we stupid owners (as defined how they treat their owners), there is nothing which would clearly indicate how ANC can be defeated (fuse, On/Off switch, etc.). In the absence of that information, the best you can do is disconnect all the speakers (don't short the leads out if you try this).

Edited November 29, 2014 by Anon2015

[andymac]

But the suburbans that we drove with the issue didnt have the noise canceling system in them. They were fairly basic trim level packages. I am not sure that is the issue ( or this issue)

[20Sierra14]

Correct me if I'm wrong, but I think most all of GM's vehicles (w/ V8 to V4) are using noise cancellation to some degree...?

 

If that is true, some people are more sensitive to the pressure in their ears that it's giving them headaches, but then most people aren't having any issues at all. It could be just the fact that their ears are sensitive enough to hear the pressure created by the NC freq...?

 

The 15' SLT we first picked up made so much noise going over dumps/rough roads it literally roared inside the cabin. I personally think the NC system was over compensating, thus creating pressure in both our ears. Now, my wife says she doesn't feel the pressure at all as the Denali is much more quiet when hitting rough roads. I, on the other hand, can still feel pressure in my ears to a degree. It isn't creating headaches like the SLT did, but I still get some popping from the pressure.

 

So... The question is - Has GM even considered the NC system? They've tried to fix the roof - Nothing. They've balanced and replaced wheels/tires - Nothing. They've replaced shocks and driveshafts - Nothing. All of this is to try to quiet the interior cabin... Right?

 

These damn Yukons are so loud inside, SOMETHING is trying to quiet them down, and that something is also giving some people headaches! What is the system designed to trick our ears? The NC system... not a rumbling roof!

 

I'm almost to the point that I'm going to pull some fuses and take the truck for a spin.

 

 

Reference to "buffering" in the new '14 Sierra about a year BEFORE the issue arose in the Yukon -- http://www.gm-trucks.com/forums/topic/153468-buffering-sound-inside-of-truck/

Edited November 30, 2014 by 20Sierra14

[andymac]

Wow. I learn something new everyday. Ok. So I checked all the trim levels of suburbans/yukons and found that only the LS chevy could come with a plain jane 6 speaker stereo and not the audio pilot nonsense from Bose. So I guess at this point, does anyone have a LS chevy that makes this sound with the 6 speaker audio system? Or does this trim level also have some sort of "make noise to not make noise system" as well. They claim all over the websites that this is the quietest SUV on the planet but yet they have to use this nonsense to make that happen? OK.. Someone just turn off that damn V4-V8 thing, turn off the ear fooling sound thing and make this all go away. Someone aught to know how to make that happen with a programmer or maybe a GM tech who wants to help out.

[20Sierra14]

They're heading the in the right direction on the "Enhanced Sound" thread

Edited November 30, 2014 by 20Sierra14

[Anon2015]

The Bose AudioPilot and Active Sound Management technologies are deployed in a significant number of brands and models. http://www.bose.com/controller?url=/automotive/manufacturers.jsp

Also understand this is not a product in the traditional sense, rather it is a suite of technologies which can be deployed into an automobile and customized to the specific needs of the automobile and the "wants" of the manufacturer. Whether or not GM, in concert or not with Bose, is investigating these technologies with respect to this issue is unknown and we will likely never know. As well, Bose AudioPilot and Active Sound Management can work together; but, AudioPilot does not imply Bose Active Sound Management systems are also installed. ("Noise Compensation" and "Noise Cancellation" are two different animals but still complimentary to each other. As well, the Bose legal department's influence can been seen ... the term is 'sound management' not noise cancellation..except with their headphones. )

 

Note: Bose has also developed and deployed magnetic suspension systems. Whether or not GM's magnetic suspension is a total in-house development or in collaboration with Bose, is not clear to me.

Edited November 30, 2014 by Anon2015

[Txsweettea3]

@andymac- I drove more than my share of Suburban LS & Yukon XL SLE both models made the horrible head and ear pressure. Definitely had the buffeting issue. My husband was also experiencing same symptoms. Nothing bothers him ever. We found no difference between the models from lower to upper end, all had issues. They are "not" the quietest ride on the planet. We both have said all along the 2014 and older had so much ridiculous wind and road noise, we bet whatever efforts were put into trying to make 2015 quieter is the problem. I test drove 2015's from May to late August and sadly gave up on plans to purchase due to their issues.

[Anon2015]

@andymac- I drove more than my share of Suburban LS & Yukon XL SLE both models made the horrible head and ear pressure. Definitely had the buffeting issue. My husband was also experiencing same symptoms. Nothing bothers him ever. We found no difference between the models from lower to upper end, all had issues. They are "not" the quietest ride on the planet. We both have said all along the 2014 and older had so much ridiculous wind and road noise, we bet whatever efforts were put into trying to make 2015 quieter is the problem. I test drove 2015's from May to late August and sadly gave up on plans to purchase due to their issues.

 

That was certainly the correct decision for you and sad hear you've experienced this in several different trucks on various lots. It is frustrating, annoying, and disappointing for problems like this (and the vibration problems noted on the new Sierra trucks) to occur when you buy a brand new vehicle. I truly hope all of you and GM get these matters resolved. In my own situation, the fact GM continues to sell vehicles with these known problems without disclosure to the purchasers (and perhaps dealers), simply furthers my case against them. Equally to the point, each time one of these situations comes up, GM and some of the Dealers act like this is a one off situation to be brushed off, pushed aside, or an effort to pull the owner through the wringer for weeks and months hoping they eventually just give up. Sad.

[calgator73]

I own a 14 silverado but rented a 15 xl slt this last week. I noticed a bit of low frequency noise between 35 and 50 when in v4 and the engine lugging slightly. As for noise canceling...i have had both dave clark and bose noise canceling aviation headsets. The dave clark headsets would cause the exact symptoms you guys are describing. The bose were perfect after they were on for a few seconds. Best of luck.

[Anon2015]

You mean Dave Clamps?

[calgator73]

Lol...they certainly could cause some discomfort.

[2NEW4GM]

****UPDATED****

Dealer replicated the noise and found that rear bucket seat makes a noise at the base attachment to floor.

After some discussion with dealer they order parts and replaced the seat base hardware and solved the issue.

Rear tires balance and improved rear vibration by 90%, I'm considering driving a couple hundred miles and take it over for re-balancing. So far no more issues and happy with the vehicle.

[yukontruckman]

Edit..see below.

Edited December 2, 2014 by yukontruckman

[yukontruckman]

Edit..see below. Sorry for multiple posts.

Edited December 2, 2014 by yukontruckman

[yukontruckman]

I've been monitoring this thread and decided to rent a 2015 Tahoe last week week for a Thanksgiving trip. Rental vehicle was a 2015 LT, 4WD, 20K miles and 3/2014 build date.

 

I did experience the buffeting issue that many have mentioned. I would not refer to it as "buffeting", but rather a feeling of pressure in your ears. Hard to describe, but the closest thing I can compare it to would be the feeling you get when flying in a plane. Acoustically, something feels "off" with the interior of these vehicles. Almost like being in a vacuum.

 

I noticed it more at low speeds when the vehicle was going over hard bumps or traveling down a dirt road. With every bump, I could feel a slight pulse of pressure in my ears. I did not notice it as much at higher speeds on a smooth road. The V8/V4 cylinder deactivation did not appear to make the problem any better or worse.

 

I have a couple of thoughts:

 

1. This new cabin is sealed up very tight. Maybe it is creating some kind of odd pressure differential with the outside air?

 

2. The Bose Noise Cancellation. I found this online regrading noise cancellation headphones:

 

10. Comfort Concerns While Wearing Noise-Canceling Headphones

The noise-cancelling effect of these headphones is achieved by creating a sound wave that breaks down the sound waves approaching it. This requires a sound, and some people complain about a hearing a humming sound when wearing them. The sound, which is actually barely perceivable, also causes some people to feel pressure on their eardrum when wearing them. Those who are sensitive to this may want to limit their use, at least until they adjust to it.

As others have mentioned, the Bose system seems suspect. It could also explain why some people hear/feel something and others do not. Not everyone hears the same frequencies or are bothered by them. I drove the vehicle for two hours straight and while I could feel the pressure at times, it didn't get to the point where I felt dizzy or sick from driving it.

GM is tearing vehicles apart, replacing wheels, tires, shocks and that hasn't fixed the problem for anyone. I think they should be taking a hard look at the cabin interior and the Bose system.