Active Noise Reduction
 

In my pursuit of fuel efficiency I have overinflated the tires on my TSX to ~45psi. Now, the TSX is an entry level sport-luxury car, but the cabin has always been relatively noisy. With the increased tire pressure, road noise is even more pronounced. The only mod I can think to do that would lessen the noise without adding weight is active noise reduction (ANR).

1. Can this technology be implemented in a vehicle application?
2. Are there stereo head units that support ANR?
3. Do you have any experience or advice concerning ANR?

Ideally, the system would use the existing speakers in the car and play nicely with the factory installed radio. Is it ok to have 2 separate sources connected to the same set of speakers? That is, can you connect 2 stereo head units to the same set of speakers without fear of damaging the output amps of the head units?

There might be a product marketed towards the general aviation crowd.

1. Yes, the variable displacement Honda V6 in the Accord uses it to mask the odd sound of only a few cylinders running.

2. Perhaps, although I am not aware of any other than the Honda unit -- and I don't know how they have implemented theirs.

3. I've used ANR in aviation headsets -- works great. I'd think that in a open car, it would be hard to get the phasing right without headphones -- but apparently Honda has figured out how to do that.

...analogy: the BOSE™ headset "noise-canceling" system integrated into the cars' audio system.

Active Noise Control, ANC, (Lotus & Harman Becker) has been installed since 1992, in a Nissan Bluebird/Stanza. Its standard in Infinitis. Interestingly, Bentley did not want it.

Bose ANC keeps the babies asleep in Honda Odyssey minivans.

Siemens, Alpine Electronics, etc. has them to cancel noise and specifically frequencies 'unacceptable' by human body harmonics.

Ferraristas bend their elbows but aftermarket muffler manufacturers are shaking.