OK, Well the fundamental difference is that a radio Tx antenna does
not have to move to create a wave. A speaker cone on the other hand
is moving to create a sound wave. Relative motion between the Rx and
Tx creates Doppler.

Not exactly true, at the very least, the EMF on the antenna will cause it to
vibrate in the earth's magnetic field, and while this has no connection to
it's radiation, Tx is still moving relative to Rx, and while this motion is
extremely small, considering the relative wavelengths and propagation
speeds, an exact analysis may find that it is similar to the speaker's cone
motion when reproducing music.


Very very very small especially when the Doppler effect is relative to
the speed of light and not sound. Also it would have to vibrate at RF
frequencies.



There is no relative motion for an RF radiator. There is relative
motion (in general) for a sound radiator. Bob has come up with some
very specific cases where there can be no relative motion between
acoustical Rx and Tx so those are exception cases.

It still has not been established beyond a doubt that there is relative
motion concerning Tx and Rx with speaker audio reproduction. There remains
an element doubt that the surface of the cone is really the literal sound
source. The center of motion of the cone may actually be the literal sound
source, and this point doesn't move relative to the listener under normal
circumstances.

But if you consider both the 50 Hz and 4 kHz vibrations cone, the
sound source at 4 kHz (wherever you consider it be) is certainly
moving at 50 Hz. Even if you consider the center of motion at 4 kHz
to be the sound source, that center is moving at 50 Hz. That is the
entire point!

Mark