"PenguiN" wrote in message
om...
The sound produced by the speaker happens because the speaker is driven
None of those approximates in any way, or
is a valid anology for a loudspeaker producing a complex waveform that
comes
from only one source, the complex electrical waveform driving the
speaker
motor. All the other anologies have two sources, one for the low
frequency
motion and one for the high frequency sound, NOT a valid anology for
what
happens when a speaker reproduced a complex waveform.

What if we take this to the extremes with a thought experiment:

Picture the largest loudspeaker in the universe sitting outside
somewhere. It's so big that it has a maximal excursion of several
feet. Now picture a very low bass signal played on that speaker at
almost maximal volume. The speaker cone is vibrating
in-out-in-out-in-out.

Now add to that signal a small, high pitched, low amplitude waveform.
The two waveforms are added together so that it seems like the higher
pitched wave is "riding on top of" the bass wave. As far as our
super-excursion speaker is concerned, the location that's generating
the high pitched sound is moving forward and backward several feet.

Fundamental flaw in the logic, the higher pitched signal is not "riding on"
the lower pitched signal, they are combined to produce a complex waveform
driving the speaker.

If you still don't believe that this scenario validates the
train-whistle analogy, why not make the bass waveform move at the
speed of, oh say a train, and have the high pitched signal on top of
it be, oh say the sound of a whistle.

Doesn't apply, the train and whistle are supplied by two separate sources of
energy.

The scenario described in this thought experiment would *certainly*
produce doppler shift in the higher signals. If you made the bass
carrier sound low enough frequency and loud enough, you would even be
able to hear the weeeooohhweeeoooh modulation of the higher frequency
as the source of that sound (the surface of the speaker cone) is
moving towards and away from you. It follows reasonably that this also
happens with regular speakers, but to a lesser extent.

Once again, comparing two separate sources of motion (the train and the
whistle) provided by two separate sources of energy, to one complex motion
source provided by one single complex source of energy (the signal driving
the speaker motor) is comparing apples to oranges.

The question of whether it's a relevant, measurable, or hearable
distortion is a separate issue from whether it physically exists.

Agreed, but in order to reach any valid conclusions, one must stop comparing
apples to oranges!