William Sommerwerck wrote:

I think there are two simple refutations, one theoretical, the other practical.

Theoretical -- If the output of a driver accurately follows its input waveform,
how can there be Doppler distortion?

Precisely, and an argument by reciprocity shows that to be
the case. If you measure the particle (voxel if you don't
like discrete) velocity and then make the reproducing system
follow that velocity function then what goes out as a wave
will be the same as what was measured.


Practical -- It should be trivial to compute the sidebands produced by combining
(say) a 60Hz signal and 6000 Hz signal. By looking at the phase of the
sidebands, it should be possible to determine what part of them is IM distortion
(AM components) and what part is Doppler (FM components).


Non-linearities mix in very wierd ways. The only real
experimental test would require a super-linear driver and
those are hard to find.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein