Been used for a long time* in refrigerators and dishwashers.
[*] long time = ~6 years.
[*] long time = ~6 years.
Active Noise Cancellation on the New Honda Odysey
- Thread starter Mitch Alsup
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Kestas
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Ruttan used it on his around-the-world-on-one-fuel-tank aircraft (Voyager?). It failed during the trip, so he and his mate suffered hearing loss from that endeavor.
I still don't see how noise can be canceled from another source. They are generated from different locations and can only cancel each other at certain locations, just like a moire pattern. At other locations they'd have an additive effect.
It's just another thing to go wrong with a car.
I still don't see how noise can be canceled from another source. They are generated from different locations and can only cancel each other at certain locations, just like a moire pattern. At other locations they'd have an additive effect.
It's just another thing to go wrong with a car.
I share your puzzlement. Perhaps somone can explain how it works when one person is 1/2 wavelength further from the nose sorce than the other person.
source has nothing to do with it. freequency does not change by locations, as it bounces around inside the car or wherever, it doesn't change. Amplitude may change, but not frequency.
it can only work with repetitive noise, the more "white" the better. Saw article on this in car usage at least 10-15 years ago. I have a pair of headphones that does this quite well. virtually eliminates all road or air noise in cars and planes. it allows me to turn down the stereo since i don't have to overpower wind noise. does nothing to voices, etc or "non-white" noises.
it can only work with repetitive noise, the more "white" the better. Saw article on this in car usage at least 10-15 years ago. I have a pair of headphones that does this quite well. virtually eliminates all road or air noise in cars and planes. it allows me to turn down the stereo since i don't have to overpower wind noise. does nothing to voices, etc or "non-white" noises.
But phase does have everything to do with it. If the sound from the speaker is 180 out of phase with the nosie source it tends to cancel the noise. If it's in phase with the source, the sound level gets louder.
Sound cancelling headphones work because their microphones are right at the speakers, a small fraction of a wave length away. Move the sense microphone 1/2 wavelength away from the speaker in the headphone and it will make the noise level louder instead of canceling it.
I would like to hear how the Honda system works, but it's not the headphone model.
I think that the system only works at low frequencies where the wavelength is much greater than the dimensions of the car. At 40Hz, the wavelength is about 28 feet, so a few feet difference in the passenger cabin won't matter much.
There are speakers on refridgerators and dishwashers?
That is what they said about VTEC. VTEC has proven to be very reliable.
I did a search online and what I found agrees with you. The thread I read said the ANC only works on very low frequency drivetrain rumble. The example they gave was around 50 Hz.
If they optimize if for a space equi-distant between the front and rear seat pasengers, there would only be foot or two difference in distance. The press releases an parroting of them makes it sound like general purpose noise cancelation system. It isn't.
Instead of spending money on their ANC, they could have left it out and called the rumble SMS (Sound of money saved)
That's relief, I thought I had voices in my head.
For a good demonstration of this, wire one, or better yet, two of the speakers in your car backwards and notice that the bass is greatly reduced.
This happened in my car due to an incorrect wiring diagram. When I corrected the wiring, all the bass came back.
I'm not laying out any of my cash until they come out with a system robust enough to cancel out the noise emanating from annoying people. . .
It's already been invented.quote:
Originally posted by ekpolk:
I'm not laying out any of my cash until they come out with a system robust enough to cancel out the noise emanating from annoying people. . .
quote:
Originally posted by XS650:
It's already been invented.quote:
Originally posted by ekpolk:
I'm not laying out any of my cash until they come out with a system robust enough to cancel out the noise emanating from annoying people. . .
Amazing huh? Active noise cancellation delevered through the stereo speakers. Active fluid engine mounts. Wow.
This is from www.greencar.com
That might cause a bit of a surprise if someone hooks up a subwoofer to the factory system. I guess that's not too common on mini-vans though.
Too bad they can't make a noise cancellation device for all the screaming kids who sit in the 2nd and 3rd row of these Odyssey's...
I think the noise cancellation device for the kids is the DVD player...
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