"Jim Carr"
"Phil Allison"

I disagree. The time delay or advance *is* Doppler.


** Doppler frequency shift is proportional to source velocity - so
they
are not the same.


Maybe we just have a failure to communicate. I say the actual frequency
does
not shift.

Since movement of either the source, observer or both can change that
distance, there is an
*apparent* shift in frequency, not a "real" shift.


** The *observed* frequency changes - end of story.


But then again, you seemed to disagree about the speed of sound being
constant when you wrote...

** If the medium is moving at some speed then that adds to, or
subtracts
from, the speed of sound in still air (ie 343 m/S)

To which I say, care to cite a reference?


** Silly question - see any school physics text.


Let's just reason it out by using the whistle on the train and the
changing
speed of sound which you cite.
Suppose further that the listener is 3,430
meters away. The sound wave has to travel 10 seconds to arrive at the
observer, right?

Train #1 is stationary and blows the whistle. A second train is moving at
100m/S. At the exact moment is parallel with train #1 it blows its
whistle.
This happens to be the exact same time train #1 blew its whistle. Based on
your statement above, the first sound of the whistle is moving at 343m/S.
The second is traveling at 443m/S.


** That wrong conclusion simply has no connection with my statement.

Both whistle sounds travel through still air to the listener.


Are you saying that the second whistle will arrive at the receiver 2.25
seconds earlier and that we would hear two separate whistles?

** Nope.




............ Phil