Scott Dorsey wrote:


No. If the motion of the cone perfectly follows the waveform, and the air
is not compressable, the pressure waveform that results in the air will be
a perfect representation of the original wave. If you can somehow arrange
for perfect coupling so that the woofer excursion perfectly matches the
input signal, doppler effects should be a non-issue. Unfortunately this
does not go along well with accurate frequency response in the real world.

However, for it to be a real, non-linear effect it must be
demonstrable in a hyperlinear transducer. All linear
imperfections in the system can be cancelled by a suitable
linear function block between the input and the transducer
such that the cone follows the waveform. If there are
non-linearities in the transducer all bets are off because
we don't really know what is the cause of the resulting
non-linear output.

[theory alert]
The reason that it must be a non-linear effect is that any
linear system has sinusoids as eigenfunctions.
Eigenfunctions are those functions which when presented to
the system as input, in any summation, result in an output
that contains only complex scalings of the magnitudes of the
input eigenfunctions, which are called the eigenvalues.
Scaling zero results in zero which means that no non-zero
eigenvalues can result in the output which were zero in the
input. The hypothetical Doppler distortion fails this test.
[end alert]


Right. It's very easy to model that effect.

Actually, for an arbitrary input it has not been done.
There is no model even that will quantitatively predict the
measured result of experiments with two tones.


Bob
--

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

A. Einstein