has anyone thought of adding noise cancellation to the car stero?

**crash893** · 03-09-2004, 08:06 PM

i bought a pair of noise cancellation headphones and they are pretty neat

i was wondering if any one ever has or thougth about applying the same concept to the car stero

you would probably need 2-4 tiny mic's and then and out put for the stero but i mean even though its a bigger area it should work right?

**DodgeCummins** · 03-09-2004, 09:08 PM

Yea, but my wife wouldn't appreciate me not listening to her.

**Altimat** · 03-09-2004, 11:02 PM

I'm thinking about it now!

http://www.andreaelectronics.com/pdf...Audio2spec.pdf

**cafn8** · 03-10-2004, 12:08 AM

Originally Posted by crash893

i bought a pair of noise cancellation headphones and they are pretty neat

i was wondering if any one ever has or thougth about applying the same concept to the car stero

Yes. About 3 weeks ago, in fact.

Phase Reverse?

**stuthemong** · 03-10-2004, 07:44 AM

my post on the other thread.

"guys none of this can work. In an automotive enviroment it is not a case of simply playing an inverted signal through the car speakers. Oh if only it was!!! (my 4th yr project would be so much simpler

)

Basically if you are interested google-> filtered X-LMS algorithm.

she's not too robust, but she'll get you started. Basically you have to make an approximation of your mic -> speaker transfter function first (system identificaiton), and then run a FX-LMS algoritm on this assumption. The algorithm uses a least squares routine to estimate correct filter weights to apply to the microphone signal to output to the car speakers.

Youll be a lot better off running bose speakers on your head - unless you like playing with these things

HTH

Stu"

Altimat - that looks interesting, do you have any other info on it?

Stu

**Ormo** · 03-10-2004, 08:37 AM

The source Altimat has linked to is a system for noise cancellation and reduction in recording for playback in a noisy environment. Not for playing back prerecorded sound in a noisy environment.

Its the kind of stuff that telephones and the like use to cancel out background noise. The stuff talked about here is a different beast altogether, and I'm not sure how viable it is.
I once read an article about Audi/VW working with a car audio company to develop a system to cancel road noise using a microphone/speaker set up. I can't for the life of me find any links to it though. Was 4 or 5 years ago when I saw it.