At 06:25 PM 10/21/2004, you wrote:
>Why don't you use a noise cancelling system?  Measure the frequency of the
>noise, and run it through your stereo amplifier phase shifted 180
>degrees?  You might even be able to make it automatically adjustable based
>on MPH.

That'd only work if the original noise was coming from behind the speakers.
The "anti-noise" has to be projected in the same direction the noise is
coming from in order to match the waveforms so they cancel. I'm waiting for
them to develop a double-layered piezo sandwich material, with the bottom
layer acting as the microphone and the top layer transmitting the
anti-noise. It'd in theory be a perfect soundproofing material. Something
like that's a long way off, though...

John Bange
'90 Vanagon "Geldsauger"