> The pressure waves from both the unwanted exterior noise and manufactured anti-noise reach occupants’ eardrums at exactly the same time and cancel each other

> The pressure waves from both the unwanted exterior noise and manufactured anti-noise reach occupants’ eardrums at exactly the same time and cancel each other out. What happens if your ears are not exactly where the system thinks they should be? If you are taller or shorter than they expect? If you are not sitting in the drivers seat? If you lean over? My guess would be that the system makes things worse more often than it makes things better, if it relies on your ears being in the correct position. The wavelength of middle C is something like 2 feet, so if your ears move by 1 foot will you be getting double noise, rather than zero noise?