[wwest]

Active noise cancelation technology only works with continuous/repetitive sound, drone of a jet engine, tire noise at 70 MPH, etc. And the cancelation effect is highly dependent on the location of the receiving human ear. Place a anti-noise sound sensor somewhere close to the driver's head, noise cancelation will be highly effective for the driver, but less so for the passenger.

Back seat in a Cadillac? NO effect.