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I just got back from a long flight sitting in the back of am Embraer jet. Without my Bose noise cancelling headset the noise was LOUD. With then on it was quiet. This got me thinking about a similar system for the Corvette. My 2017 Honda CR-V has this built in.
Does anyone make such a device we could use to help with the noisy interior of the Corvettes?
Seems to me this is pointless to put in a sports car. Do folks really buy these type cars and want a totally silent experience?
if you did not have it you might have a different opinion ....it was tough to have a conversation in my C6 with runflats at highway speeds , so while it's nice to hear the motor ....its also nice not to go deaf driving it for any lenght of time
Dave
The C7 LT1 and LT2/LT3 Bose systems all have active noise cancellation. That's what the microphones in the door panels are for. As discovered by people who have added aftermarket subwoofers, those 2 microphones need to be disconnected to disable the noise cancellation (which is not tuned to work with an aftermarket subwoofer).
The LT2 and LT3 systems have an added subwoofer (in the back of the cargo compartment) and a DSP feature which allows you to select the focal point of vocals, either enhanced for the driver, or off (all passengers). Also, I am pretty sure that all these systems have "speed compensated volume".
The C7 Bose system does not synthesize engine or exhaust noise, and play it over the cabin speakers, like some BMW and VW/Audi systems do.
Noise cancellation systems are only effective at the lower frequencies of engine and exhaust noise, not as effective for the higher frequencies of tire/road noise.
Last edited by ersatz928; Nov 1, 2018 at 11:10 AM.
What I got from that link is best summarized, IMO by NSC5:
"The early Bose press release that goes into some detail makes it appear the C7 only has the audio pilot which is an "improved" version of what Bose has used for years. … So to compensate for tire noise low level audio signals from the entertainment unit would be further amplified as necessary to overcome noise in this particular frequency band. Audio signals outside of that band and signals within that band that are sufficiently loud would not be modified."
Bottom Line:
It's NOT noise canceling like Bose headphones etc that generate a 180 degree out of phase sound of the external "main high volume sound waves" it just adjusts some of the sound system frequencies (assume it has to be turned on) to help. So it attempts to "compensate"-NOT "cancel" noise.
My method of dealing with the C7 Coupe very noisy interior may not be for everyone but works for me. Had an early 2014 Z51 that was the noisiest Vette of 4 I have owned. My current Grand Sport is a bit worse! My solution is simple. I have the sound system always on, playing one of over 1000 songs in shuffle mode from a Thumb Drive as soon as I start the car. It comes on automatically.
Janis Joplin singing "Cry Baby" or a more modern Joss Stone singing "Tear Drops" drowns out the tire and road noise. The issue I had, that is now solved, is some songs, like Joss Stone's "Tear Drops," has a very boomy bass when set at where 90% of my songs were fine. In fact the bass is needed to cover the interior noise. Compared to my C6 Z51 that needed a subwoofer but with Bose hard to add the 2LT, 3LT added subwoofer works great for my purpose!
A poster had a solution similar to the custom subwoofer and amp I added to my S10 pickup that included a remote base volume adjustment I mounted on the console. I could adjust the base to fit certain songs without having to lower the total volume, which for the C7 defeated the noise covering! This is a PDF on how to do what is shown in the pic below: http://netwelding.com/Boomy_Bass.pdf
When a song stars playing that has a boomy bass I just press a lower bass volume preset!
I have 3 presets at different bass volume levels. You can set any balance, volume etc desired and remember it in a preset. As I did you can also label the presets to whatever you like! The PDF has a step by step pic/text as how.
Maybe that thread I posted was not the correct one. ...
there is active noise compansaition using the subwoofer to cancel out any lower frequency " booms" that would be heard without the technology
Fourth paragraph down ......I am confident that it works the same as the Bose headphones ..... https://www.edmunds.com/car-reviews/...ut-the-c7.html
It uses a microphone in the cabin to monitor background noise and an algorithm to analyze the music signal and adjust it to reduce the effects of sounds from outside, things like the rumble of the engine and noises from outside
The C7 LT1 and LT2/LT3 Bose systems all have active noise cancellation. The LT2 and LT3 systems have an added subwoofer (in the back of the cargo compartment) and a DSP feature which allows you to select the focal point of vocals, either enhanced for the driver, or off (all passengers). Also, I am pretty sure that all these systems have "speed compensated volume".
The C7 Bose system does not synthesize engine or exhaust noise, and play it over the cabin speakers, like some BMW and VW/Audi systems do.
Noise cancellation systems are only effective at the lower frequencies of engine and exhaust noise, not good for the higher frequencies of tire/road noise.
Read all the talk on this subject and it appears what the corvettes have is a system to compensate the audio for cabin noise and NOT noise cancellation. Seems that the two are confusing people.
If I'm wrong please give me a link to the Owner's Manual or an official GM document that specifically states noise cancellation.
Maybe that thread I posted was not the correct one. ...
there is active noise compansaition using the subwoofer to cancel out any lower frequency " booms" that would be heard without the technology
Fourth paragraph down ......I am confident that it works the same as the Bose headphones ..... https://www.edmunds.com/car-reviews/...ut-the-c7.html
Even after reading I'm NOT. Bose (and similar headphones) and the the old Lotus Muffler noise canceling work by generating a sound that is 180 degrees out of phase with the loudest of the external sounds. Works OK at the jet engine high frequency noise when I fly. But that is a relatively narrow frequency and volume they can analyzed and an equal volume sound generated a similar frequency180 degrees out of phase to cancel!
Had one of the early Bose headphones since I was flying quite a bit. In fact have a Tinnitus noise frequency that is about the high frequency of a jet engine, no doubt those several million mile flying hours were the cause! In fact, joined the Tinnitus Society years ago to see what could be done. After reading their monthly newsletter for about 9 months one article made me realize why the Bose/Lotus "noise canceling" couldn't work even though mine is a very clear fixed frequency! That is because there is no external noise causing the issue, it's strictly a nerve sending a false signal!
Actually I have found it's not a problem I just don't think about it and unless (like now) when I do, then it's pretty loud. But I'll post on some other fun topic for me and it just "goes away- in my mind!" In fact have not thought about the noise form serval weeks!
So is there a system we could buy that would give us effective noise cancellation at highway speeds?
The factory sound system in our 2017 2LT sounds very good up to 40 mph, acceptable 40-60, and almost worthless above 60 because of noise.
A system that uses headphones but would allow us to listen to the music or to conversation, would be great.
Headphones are illegal in some areas, but so is exceeding the speed limit and most people survive. And the car is so noisy that "good" sounds like ambulance sirens, warning horns, etc are drowned out just like the music.
The problem with the Bose system in the C7 is the amp and subwoofer combination are pathetic. Bose knows this so it artificially boosts bass at low volumes then has to cut it at higher volumes since the amp runs out of power quickly which distorts the subwoofer badly.
Unlike the Bose headphone which actively cancel noise (as explained very well above) is that is the microphone feedback (aka Audio Pilot) used in the C7 can not reproduce the required frequencies at a high enough level to be truly effective. Honestly I think the system makes things sound worse as its constantly messing with the audio signal. Plus the default tuning of the system isn't very good. In comparison the headphones work much better because the ear muffs completely isolate the sound. In the car there are many surfaces (plastic, glass, leather, etc) the cause all kinds of reflections at multiple frequencies. You need a sophisticated DSP along with serious amplifier power and excellent speakers to overcome such problems. The Bose / GM system is nowhere near good enough. My wife's car (Infiniti Q60) has a Bose system that sounds much better mainly because its doesn't have this Audio Pilot crap.
As Jerry noted the Bose headphones (and competing systems) use true active noise cancellation where the undesired noise is sampled, phase shifted 180 degrees, and algebraically added at the proper level so that the undesired noise is canceled. This is a very effective technique and is used in many applications including test and measurement systems and directive antenna arrays. But trying to implement it for audio frequencies in an open space like the cabin of a vehicle isn't practical because the phase shift has to be exactly 180 degrees between the actual and recreated noise source AT the exact position of the noise receiver. Unlike the headphone example where the interfering noise source is sampled at one point in space and the corrective signal is injected at the same point in the automotive environment you have a large area with multiple occupants and the corrective signal is emitted by numerous transducers located throughout the vehicle. While you can do sampling of noise at a single point (like at the driver's head area) the corrective signal will only be correct for the driver and only for the driver as long as his/her head is in a very narrowly defined area.. For an open space d a very complex algorithm wold be required to provide the corrective signal adjusted for the frequency response and propagation delay of a number of different discrete amplifiers and transducers located throughout the car and such a system would not make the passenger happy where parts of the noise spectrum would be reduced but others would be increased because of the phase relationship between the corrective and actual noise at different locations.
In a optimal setting this type of interference reduction can near perfection but the technique isn't suitable for large environments with multiple noise sources and recipients.
[QUOTE=Travelor;1598253971]Read all the talk on this subject and it appears what the corvettes have is a system to compensate the audio for cabin noise and NOT noise cancellation. Seems that the two are confusing people.
If I'm wrong please give me a link to the Owner's Manual or an official GM document that specifically states noise cancellation.
The C7 DOES HAVE Active Noise Cancellation....from the GM Factory Service Manual, Volume 2, page 8-9 . I am not sure why GM does not list this feature in the brochures.
Last edited by ersatz928; Nov 1, 2018 at 11:11 AM.
Noise cancelling device?
