Jim Carr wrote:

With that said, help me out here. I can't get myself away from the
assumption that since a speaker diaphragm has a throw of a certain distance,
then the waves started by the diaphragm may be started from any point in
that throw. As such two waves which are created a certain time apart may end
up traveling different distances to reach my stationary ear, thus a Doppler
shift. Measurable? I dunno. Discernible to my ear? Probably not.

To recapitulate, the problem with that intuitive view, which
is the whole basis of believing that there is "Doppler
distortion" is that it assumes that the distance from the
driver is the distance from the instantaneous position of
the piston. That's wrong. The distance from the driver,
since it is riding the wave it is creating, is the distance
from its zero or rest position, the position about which it
oscillates. That doesn't change with the nature of the
signal unless there is a DC component.

If the distance from the driver is not changing, there is no
Doppler shift. None of the proposed scenarios which have
the face of the driver oscillating about a rest position
will produce Doppler shift despite intuition.

Whew!


Bob
--

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

A. Einstein