2015 Tahoe "Enhanced Sound"

The Zip · November 25, 2014

Anon2015 - “One” meaning having the buffeting noise like the folks are experiencing on the Yukon in Noise in Cabin thread, got it. You know, it would be a nice coincidence if someone from that thread just happen to live in your neighborhood. Oh well..

Understanding your intelligence on the subject as a backdrop, I will still apply part 1 of a theory. Part 2 of the theory involved Bose, in which you said may be unobtainable, I’ll put that on standby for now. If it works, great. If not, well I can’t break something that’s already broken. I won’t talk about it until I do it, don’t want someone else to try it first and look at me if they screw something up or void their warranty. After all, I’m not intelligent about this, just going to apply a little smarts.

The biggest hurdle for me, finding someplace to turn-up the sound. With all the 90 yr old folks in my neighborhood, that would be just too inconsiderate. You can imagine the looks.

BTW, America fails without a volunteer, the most respected person in the country. Hats off to ya’ man.

reels · November 25, 2014

This thread reminds me of this

blackout07 · November 26, 2014

This thread reminds me of this

The Zip · December 1, 2014

Anon2015 – Tell me if the following paragraph is logical. BAP does not work when I just sit in the vehicle and play an external radio source, so this would infer BAP does not operate off DC power. But when the RKE transmitter is in close proximity of the vehicle, BAP is “active” even without the vehicle running. Active does not mean BAP is “engaged”, rather engaged meaning BAP is receiving sound. In order for BAP to receive sound, one of it’s components has to pick-up sound.

Short of disconnecting speakers, once active by the RKE, to my knowledge BAP does not have an on/off switch. So that takes me to the component that picks-up sound, a microphone. If the mic/s are shut down in my truck, BAP would be “active” but not “engaged”. So in theory, if I lock down my mic/s it should impact the buffeting. Yes or no.

A Chilton or Haynes would come in handy right about now.

Anon2015 · December 1, 2014

What do you mean Bose AudioPilot doesn't work off DC power? I suspect you mean, it is not powered until the vehicle's accessories are powered rather than operational at all times.

"But when the RKE transmitter is in close proximity of the vehicle, BAP is “active” even without the vehicle running"

I would very much doubt this is the case. If BAP is providing any noise cancellation activities, at the best case, it would not be active until such time as the Intellilink display powers up at the earliest. If BAP is providing only noise compensation functions it would not be active until the audio system is turned on. Note Bose AudioPilot can be turned off in the audio settings menu.

Now, let's separate two issues: Noise compensation and noise cancellation. Clearly there is no noise compensation when the audio system is off or Bose Audio Pilot is turned off in the system menu. There appears to be no independent way to disable noise cancellation by way of a fuse or an on/off setting in the system menu. It may be possible through the vehicle's diagnostic interface. Turning off Bose AudioPilot is not turning noise cancellation off.

It is not clear, and GM has not disclosed (to me in any case), exactly what noise cancellation functions have been enabled on your specific make/model. I was told by a GM Engineer, noise cancellation is engaged only between a single very specific RPM range. I have not verified the veracity of that statement. That is entirely possible and logical. I do know as far as road noise is concerned, whatever noise cancellation system the truck may have, it is doing exactly zip, nada, nothing. For the engine noise within a given RPM range being a very specific case, no microphone is required (better with one, but not required none-the-less). Therefore, the only absolutely 100% effective means to completely disengage noise cancellation is to disconnect all speakers (in the absence of direct access by means of the vehicle's OBD port.)

yukontruckman · December 2, 2014

What do you mean Bose AudioPilot doesn't work off DC power? I suspect you mean, it is not powered until the vehicle's accessories are powered rather than operational at all times.

"But when the RKE transmitter is in close proximity of the vehicle, BAP is “active” even without the vehicle running"

I would very much doubt this is the case. If BAP is providing any noise cancellation activities, at the best case, it would not be active until such time as the Intellilink display powers up at the earliest. If BAP is providing only noise compensation functions it would not be active until the audio system is turned on. Note Bose AudioPilot can be turned off in the audio settings menu.

Now, let's separate two issues: Noise compensation and noise cancellation. Clearly there is no noise compensation when the audio system is off or Bose Audio Pilot is turned off in the system menu. There appears to be no independent way to disable noise cancellation by way of a fuse or an on/off setting in the system menu. It may be possible through the vehicle's diagnostic interface. Turning off Bose AudioPilot is not turning noise cancellation off.

It is not clear, and GM has not disclosed (to me in any case), exactly what noise cancellation functions have been enabled on your specific make/model. I was told by a GM Engineer, noise cancellation is engaged only between a single very specific RPM range. I have not verified the veracity of that statement. That is entirely possible and logical. I do know as far as road noise is concerned, whatever noise cancellation system the truck may have, it is doing exactly zip, nada, nothing. For the engine noise within a given RPM range being a very specific case, no microphone is required (better with one, but not required none-the-less). Therefore, the only absolutely 100% effective means to completely disengage noise cancellation is to disconnect all speakers (in the absence of direct access by means of the vehicle's OBD port.)

Anon,

Check this video link posted by 20Sierra14 in the "Noise in cabin thread"

It is from 2010, but states that the system functions between 1000 and 3000 RPM and utilizes the front door speakers and the rear subwoofer. Knowing GM, this is probably the same exact system being utilized in the 2015 Tahoe/Yukon.

This is interesting because some have stated that the "buffeting" sound is worse in the front seats and I wonder if the subwoofer could be producing a low frequency sound that some people would interpret as pressure in their ears.

The Zip · December 2, 2014

The size/volume/length (SVL) of the GM Fullsize SUV line, extra speakers and mic/s to compensate for the SVL, and the SUV being jelly tight is also a factor impacting the Bose Active Sound Management System (BASMS) as compared to other manfacturer vehicle lines using BASMS. I filed a complaint with the NHTSA and will schedule a service visit with my local dealership. My complaint will be about the subject as this is very easy to duplicate. I may even tell the service advisor to sit in the vehicle after I intentionally left the volume on blast with a culprit tuned radio station (just thinking out loud here).

Dealerships are not looking at the Bose system, which I believe to be causing the buffeting issue, whether it's Noise Compensation or Noise Cancellation. But I do believe there is a fix, post #s 6/7/8, Rapid Mode Transition (RMT). Bose more than likely was asking too much for the technology and GM said it wasn't going to happen, my thoughts. But read the following paragraph on RMT and convince me this would not mitigate if not minimize what folks are experiencing. Make your own conclusion.

RMT module is an optional, add-on feature for Bose Engine Harmonic Cancellation (EHC) or Engine Harmonic Enhancement (EHE) that provides additional capabilities for managing complex noise challenges associated with variable powertrain and cabin modes. When multiple tuning modes are required to achieve a desired powertrain sound character (cylinder deactivation/reactivation, hybrid operation, etc.), the transitions between modes may require special control, thus RMT. (para obtained from Bose site)

Anon2015 · December 2, 2014

I believe your issue should be filed as you have. I don't have a dog in this fight and cannot file myself.

I do believe that dealerships are not looking at Bose or any other acoustic system installed on the vehicles and I think largely due to a lack of knowledge about acoustics. By the same token, even since GM and Bose have been advised of the potential these systems could be at fault, it doesn't appear they are working the issue from that aspect (or may just be in the finger pointing phase between GM and Bose. We as owners are stupid on all affairs automotive and therefore are not to be taken seriously.

I have no first hand knowledge with respect to the use, of not, of RMT. I would however suspect it is installed...that is being logical which, of course, may not be the proper way of thinking.

Anon2015 · December 2, 2014

"Check this video link posted by 20Sierra14 in the "Noise in cabin thread"

Thanks. I did have the opportunity to see this just over a year ago. From what I have been told this is the same approach used in the larger vehicles although the RPM range is likely different and may not be the total approach.

The Zip · January 15, 2015

Filed a complaint with Chevy and also with NHTSA early Dec '14, the Enhanced Sound was not pronounced enough for the dealer to pull the headliner and muffle my mics (file your problem with the dealer, if GM finds a fix, filed complaints will probably start first). Understanding how Bose wrote, described, and displayed a visual about the operation of the Audio Pilot (AP), the mics seem to be the head of the snake. Others may have their interpretation of the AP, but then they will have to start another thread.

When I started the thread, I made the decision to do something about the Enhanced Sound regardless if the dealer decided to do nothing. By looking at the electrical plan for a few months, I knew I couldn't see my mics but I knew a few options to muffle them. Three of the options weren't probable because those measures would void a portion if not all of my warranty. The options were pulling the fuse, pulling the mic pins from the fuse, and pulling the mic pins from the amp (some vehicles have 2 amps, wasn't quite sure where my amp was but I believe it is in the center console versus in the back near the jack). So all of those options were out. There may be other external options (Bose or GM), but I can't control those.

My last option left, the head of the snake (the mic). The issue as I see it at the source versus the other options being close to the source. I came up with 4 ways to mitigate the mic (none of which will invalidate the warranty; nothing will be pulled, cut, or disconnected) and went as far as to purchase materials to test. One big problem, I couldn't get to the mic, they are located under the passenger headliner. After visiting the "2015 Yukon Noise in Cabin" thread, it was noted that the GMC Fullsize SUVs have their mics exposed. So the follow-up to this thread will finish on the "2015........Cabin" thread. Will someone be willing to try it, don't know. Will it work, don't know. But when safety is the issue, doing nothing shouldn't be an option.

The Zip · January 15, 2015

anon2015 - why when I play other media (say CD) on the system versus using XM, the Enhanced Sound is not there. Even when turning the volume at max blast. On XM, volume can be at 40% at best and the Enhanced Sound is unbearable. Can you explain, thx

Anon2015 · January 15, 2015

Yes, I have noticed that as well; however, when playing a CD, DVD, or BluRay, they would be using industry decoding (Dolby for example). Why the Bass is so exaggerated from XM is either something XM is doing or Bose is mucking with something (or alternatively, changing the DSP settings to kill the 20k rolloff or a ramp to increase the <20K frequencies. I'll have to find an HD off air station I can tolerate and see if the same effect is happening there. I'd kill to have (a) better access to the DSP controls and/or (b) a system with Logic 7 or Trifield installed.

The Zip · January 15, 2015

anon2015 - are referring to "better access to the DSP controls" more than the DSP provided modes (normal/driver/rear/centerpoint)? Adjusting these modes along with turning off Auto Volume was also a plus.

Anon2015 · January 15, 2015

yes....beyond those four. BTW...I did have the opportunity for a short listen on an HD station. The overbearing bass wasn't present and the sound field more akin to DVD/CD...but, once again, HD requires the use of standard decoding and it doesn't appear Bose is attempting to augment something or provide ambiance extraction (not clear...just would appear that way from a five minute ride down the freeway).

The Zip · January 16, 2015

anon2015 - I have been thinking the Enhanced Sound effect was with Bose, but if that were the case the effect "should" be happening with all media (cd/dvd/blu ray/hd) based on the ANC execution. Bose plays the media as best as it can (even a few XM channels) without the Enhanced Sound, not to say there couldn't be a better system installed. I've done too much research on the Bose sound/noise effect and you are a subject matter expert, so I believe the issue to be with XM specific channels. It seems some channels and the Bose system are in conflict.

I'll see what XM has to say...