"Ben Bradley" wrote in message
news
On Mon, 16 Aug 2004 21:57:16 -0500, "Porky" wrote:


"PenguiN" wrote in message
. com...

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.

Have two amplifiers, one for the low frequency connected to the
speaker through an inductor, another amp outputting the high frequency
connected to the speaker through a capacitor. Thus the low and the
high are supplied by two separate sources of energy.

Actually, isn't the train whistle powered by steam from the same
boiler that powers the wheels, moving the train? What's up with that?

But seriously, for Bob and other anti-doppler-distortion folks, how
does cone-and-frame movement cause doppler while cone movement only
does not? What is it about the frame that causes doppler?

If you put the speaker on a shaker table, run 1kHz and 50 Hz
through the speaker, move the shaker table at 50 Hz opposite the phase
to the speaker so the cone only moves at the 1kHz rate with respect to
the air, will it generate doppler distorion? According to my
understanding of Bob's position, it should.

The whole thing hinges on the single complex waveform vs multile simple
waveform idea. If the two sound signals are mixed into a single complex
signal and that signal is what drives the cone, there are not actually two
discrete signals being converted to sound, there is a single complex signal
that our ears interpret as two different sounds. This isn't an exact anology
either, but it's better than the train/whistle thing.
If you play a CD of an orchestral performance, there is not one piece of
analytic equipment man has ever designed or built that can completely
separate and isolate the individual instruments, but any human with decent
hearing and a bit of training can. This would seem to support the argument
that the speaker is producing a complex waveform as a whole, not as a bunch
of individual tones. If this is true then there can be no Doppler distortion
in a speaker that is reproducing the signal in a linear manner. Doppler
shift can only exist when one vibration is riding on another vibration or
source of motion, it cannot exist when all vibrations are being produced as
a single complex waveform.
That is as simply as I can explain it. I'll go either way with the
Doppler argument if someone can prove that the speaker isn't generating a
complex waveform, but is generating a series of simple tones.
The fact that I drove my big speakers with a 20Hz tone combined with a
500Hz tone at a level that the online proponents of Doppler distortion said
would produce audible Doppler shift, and it didn't, tends to make me think
that Doppler shift doesn't occur under those conditions.

Randy Yates wrote:


Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion." It shouldn't be
incumbent on those that observe that no predictive theory
exists to prove why it doesn't, although I've been trying,
it should be incumbent on those claiming that it exists to
produce the predictive theory. Have at it. This isn't
string theory. If it's there, a precise model should almost
fall out by inspection.


Bob
--

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

A. Einstein

Arny Krueger wrote:


If you do the math, nonlinearities can't produce FM distoriton. You need
something that operates in the time domain, not the amplitude domain.

If you do the math, FM distortion and linearity are mutually
exclusive. This is not debatable. Find a rigorous
definition of linearity. I've presented it but it doesn't
seem to have taken hold despite it being the bedrock of
linear systems theory.


Bob
--

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

A. Einstein

Bob Cain writes:

Randy Yates wrote:

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

Randy has spoken. Without one shread of a predictive theory. Odd,
that.

Have you ever been to Ethiopia, Bob? We might as well be debating whether
or not gravity exists there. I've never been - you've never been - so
we can't say experientially, so it's open for doubt, right?
--
% Randy Yates % "The dreamer, the unwoken fool -
%% Fuquay-Varina, NC % in dreams, no pain will kiss the brow..."
%%% 919-577-9882 %
%%%% % 'Eldorado Overture', *Eldorado*, ELO
http://home.earthlink.net/~yatescr

"Porky"

"Phil Allison"


** This little piggy cannot trot and chew gum at the same time.

Are you kidding?



** Not one bit - you are clearly an utter imbecile.




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

"Bob Cain"


** The original non ambulatory gum chewer.





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

Bob Cain writes:

Randy Yates wrote:

Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion." It shouldn't be incumbent on
those that observe that no predictive theory exists to prove why it
doesn't, although I've been trying, it should be incumbent on those
claiming that it exists to produce the predictive theory. Have at it.
This isn't string theory. If it's there, a precise model should
almost fall out by inspection.

If by "predictive theory" you mean a theory by which this phenomenom
can be predicted, then I must ask if you are blind. I have stated it
several times in several different ways. I have cited a reference for
it (Halliday and Resnick). I am assuming you are familiar with the
theory. Is that assumption invalid? Do you want a rehashing of the
theory of the Doppler effect? Do you want me to transcribe my Physics
text into a usenet news article for you so you don't have to go to the
library and check one out?
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

Bob Cain writes:

Randy Yates wrote:

Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion." It shouldn't be incumbent on
those that observe that no predictive theory exists to prove why it
doesn't, although I've been trying, it should be incumbent on those
claiming that it exists to produce the predictive theory. Have at it.
This isn't string theory. If it's there, a precise model should
almost fall out by inspection.

I dunno Bob, are you SURE that current will flow when you place the
220 VAC electrodes across your temples? Why don't you try it. You
never know - you may be in a reference frame in which Maxwell's
equations no longer hold.
--
% Randy Yates % "Ticket to the moon, flight leaves here today
%% Fuquay-Varina, NC % from Satellite 2"
%%% 919-577-9882 % 'Ticket To The Moon'
%%%% % *Time*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

"Bob Cain"


Randy Yates wrote:


Proof by assertion?

Sorry, Randy. I see nothing but proof by assertion from the
supporters of "Doppler distortion."


** Cos you are such an utter ass you refuse to see it.



It shouldn't be
incumbent on those that observe that no predictive theory
exists


** What dishonest rot, Doppler theory is ancient.



If it's there, a precise model should almost fall out by inspection.



** I posted a link with the maths of a precise model.

Shame you are too big an ass to recognise it.





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

"Bob Cain"

If you do the math, FM distortion and linearity are mutually
exclusive.

** Big lie.

This is not debatable.


** The words of an ass.

Find a rigorous
definition of linearity.


** Find a relevant one.


I've presented it but it doesn't
seem to have taken hold despite it being the bedrock of
linear systems theory.


** Another masive lie from a dangerous fool.





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

"Bob Cain"

What theoretical prediction might that be? I've yet to see
a theory for "Doppler distortion" that predicts. Odd, that.


** This imbecile has never studied physics in his life.

The kind in books OR the real world of nature.




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

"Porky"


** This little piggy cannot trot and chew rotten fruit at the same time.



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

"Porky"

The fact that I drove my big speakers with a 20Hz tone combined with a
500Hz tone at a level that the online proponents of Doppler distortion
said
would produce audible Doppler shift,


** What level was that and WHO said so ????




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

Bob Cain writes:

If you do the math, FM distortion and linearity are mutually
exclusive. This is not debatable. Find a rigorous definition of
linearity. I've presented it but it doesn't seem to have taken hold
despite it being the bedrock of linear systems theory.

You need remedial work in logic, Bob. Even though the
statement "A - B" may be true, there is nothing you can
conclude if A is not true.

"*IF* a system is linear, then it will not exhibit the Doppler
effect" is a true statement. However, get this:

T H E S Y S T E M I S N 'T L I N E A R !!!!!!!!!!!!!!!

Note carefully, (for thine ist a beanhead): the "system" here is
defined to be the entire electro-mechanical path from the speaker's
electrical input to the acoustic receiver's input.
--
% Randy Yates % "Maybe one day I'll feel her cold embrace,
%% Fuquay-Varina, NC % and kiss her interface,
%%% 919-577-9882 % til then, I'll leave her alone."
%%%% % 'Yours Truly, 2095', *Time*, ELO
http://home.earthlink.net/~yatescr

Ben Bradley wrote:


Someone should have just said at the start "Bob Cain (and a few
others here) is in denial about the existence of Doppler effect in
speakers" and I wouldn't have tried so hard...

C'mon, Ben, let's not go there. I have skills in that
direction too and would much rather keep them in their sheath.

Let's keep this to techical give and take rather than
resorting to that kind of stuff.

How about giving us a predictive theory for "Doppler
distortion" that can be tested against experiment?

I have a predictive theory, the effect is zero for all
signals and have proposed a simple, if not inexpensive,
experiment that will remove from considerations all effects
that the speaker mechanics have on the piston/air interface.


Bob
--

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

A. Einstein

"Phil Allison" wrote in message
...

** The words of an ass.

Can't you do any better than calling people names?

Ben Bradley wrote:


But seriously, for Bob and other anti-doppler-distortion folks, how
does cone-and-frame movement cause doppler while cone movement only
does not? What is it about the frame that causes doppler?

This is beginning to feel like an Einstein/Bohr debate. Not
in the capabilities of the participants but in the nature of
it. :-)

My answer to this is that you must always consider the
entire generating system. You must find the rest position
of that entire system. In the frame of reference of
(attached to) that rest position, there will be no "Doppler
distortion."

The air is capable of carrying any time varying signal but
not an unvarying one. What it does in a frame of reference
that is moving with constant velocity relative to that rest
position is Doppler shift it. If the motion is varying in
time it is linearly superimposed on the signal being emitted.


Bob
--

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

A. Einstein

Bob Cain writes:

Ben Bradley wrote:


But seriously, for Bob and other anti-doppler-distortion folks, how
does cone-and-frame movement cause doppler while cone movement only
does not? What is it about the frame that causes doppler?

This is beginning to feel like an Einstein/Bohr debate. Not in the
capabilities of the participants but in the nature of it. :-)

My answer to this is that you must always consider the entire
generating system.

"Entire generating system." Now there's an ill-defined statement.

You must find the rest position of that entire
system. In the frame of reference of (attached to) that rest
position, there will be no "Doppler distortion."

In the frame of reference of the acoustic emitter,
there is no Doppler shift. That is certainly true.

The air is capable of carrying any time varying signal but not an
unvarying one. What it does in a frame of reference that is moving
with constant velocity relative to that rest position is Doppler shift
it. If the motion is varying in time it is linearly superimposed on
the signal being emitted.

Please explain to me why the wavelengths perceived by an observer
experiencing a time-varying velocity relative to the source will
not also experience a time-varying Doppler shift.
--
% Randy Yates % "With time with what you've learned,
%% Fuquay-Varina, NC % they'll kiss the ground you walk
%%% 919-577-9882 % upon."
%%%% % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr

Randy Yates wrote:

If by "predictive theory" you mean a theory by which this phenomenom
can be predicted, then I must ask if you are blind. I have stated it
several times in several different ways. I have cited a reference for
it (Halliday and Resnick). I am assuming you are familiar with the
theory. Is that assumption invalid? Do you want a rehashing of the
theory of the Doppler effect? Do you want me to transcribe my Physics
text into a usenet news article for you so you don't have to go to the
library and check one out?

It is hard for me to believe that you don't know that a
predictive theory is one for which there is a mathematical
model which can predict, with accuracy, the results of the
kind of hypothetical situations that are being bandied about
in order to compare measurement to theory. Where is it?


Bob
--

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

A. Einstein

"Phil Allison" wrote in message
...

"Porky"

"Phil Allison"


** This little piggy cannot trot and chew gum at the same time.

Are you kidding?



** Not one bit - you are clearly an utter imbecile.


And you are clearly a mental midget who must cover his ignorance with
flippant comments and smart-alecky remarks which have nothing to do with the
topic at hand. You are obviously in the wrong newsgroup, you should be in
the alt.binaries.rotten-fruit-chewing-idiots group. From the scope of your
input so far, you clearly have nothing to contribute to any of the groups
this thread is a part of. Go crawl back under your rock, junior.

To the rest of the members of the various groups, I apologize for the
outburst, but this jerk started it and he clearly had it coming.

Randy Yates wrote:

"*IF* a system is linear, then it will not exhibit the Doppler
effect" is a true statement. However, get this:

T H E S Y S T E M I S N 'T L I N E A R !!!!!!!!!!!!!!!

Well, Randy, many people are saying that it is and produces
FM distortion anyway.


Note carefully, (for thine ist a beanhead): the "system" here is
defined to be the entire electro-mechanical path from the speaker's
electrical input to the acoustic receiver's input.

**** you, and I say that with all due respect. The system
here is everything from the face of the piston on out.
Nothing that occurs before that can be contributory and must
be eliminated in some way from any experiment designed to
catch Doppler at work.

Again, give me a mathematical expression which describes in
a quantitative way what should be measured at a distance
from that speaker as a function of the motion of that speaker.

Until that is done, "Doppler distortion" is not supported in
theory. I sincerely hope no one will say that it isn't
required because you see evidence of frequency modulation.
According to a recent post, even that evidence may not
really indicate frequency modulation but can be accounted
for by non-linearity in the driver. I don't know the
intricasies of modulation theory but it was said by someone
who does that the data shown does not carry the signature of
this supposed effect.

Until "Doppler distortion" is supported in theory, and I
hope all know by now what qualifies as a theory, there is no
basis for it and no basis for correct interpretation of any
measurement data.

This is just basic science, folks.



Bob
--

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

A. Einstein

"Bob Cain" wrote in message
...


Porky wrote:


This whole argument is based on the wrong assumption that the high
frequency source is "riding on" the low frequency source like a whistle
on a
train. It is NOT! Both sounds are being produced simultaneously by the
complex electrical waveform driving the speaker cone which moves in
accordance. Assuming that the speaker is being driven within its linear
limits, the cone's motion accurately follows the driving signal, and it
is a
linear system.
Forget the train/whistle anology, it is not an accurate representation
for
what goes on with a speaker, period!

What he said. Is this the same Porky that I've argued with
about _so_ many things?


:-) Yep, I just had an attack of common sense before I started posting
again. I decided to try to contribute positively to the group and to forget
about any preconceived notions I may have had about group members. It seems
that after doing so, my opinions of many of you went up quite a bit, which
means that it was my misconceptions that were the problem. I apologize to
all for that.
Note that I'm not necessarily agreeing with you about Doppler distortion,
but I am noting that most of those arguing in its favor are doing so on the
basis of the train/whistle analogy which is an entirely different animal.
Any theories based on that model don't necessarily apply to a "speaker cone
driven by a single complex waveform" model. Unless someone can provide
concrete proof based on real world measurements or provide an argument based
on the "speaker cone driven by a single complex waveform" model, I'm still
on the fence but leaning toward your side.:-)

"Porky"
"Phil Allison"


** This little piggy cannot trot and chew gum at the same time.

Are you kidding?



** Not one bit - you are clearly an utter imbecile.


And you are clearly a mental midget who must cover his ignorance with
flippant comments and smart-alecky remarks which have nothing to do with
the
topic at hand.


** When I saw YOU doing EXACTLY that I gave up trying to correct you.

I repeat : YOU are clearly an utter imbecile.




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

"Randy Yates" wrote in message
...
Bob Cain writes:

Randy Yates wrote:

Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

Randy has spoken. Without one shread of a predictive theory. Odd,
that.

Have you ever been to Ethiopia, Bob? We might as well be debating whether
or not gravity exists there. I've never been - you've never been - so
we can't say experientially, so it's open for doubt, right?
--
Randy, it appears to me that you're still using the train/whistle model
as a basis for the self-evidence of your claim, and if that model applied to
this case you would be entirely correct. However it doesn't apply to
loudspeakers producing complex waveforms. Your "gravity exists" example
might be true under certain specific conditions, but if you're in a freefall
dive in a plane over Ethiopia, gravity doesn't exist as far as you're
concerned, at least until the plane starts pulling out of the dive.
The problem here is whether the sound source is actually moving relative
to the listener, when the source is a speaker being driven by a complex
waveform. There are models that show that the actual source of the sound is
a point or plane that lies approximately at the center of the motion
described by the cone (I say approximately because the inertia of the cone
and of the air it is acting on may move the source a bit). If these models
are correct, then the source of the sound is not in motion relative to the
listener and therefore Doppler distortion does not and cannot exist in a
speaker. Certainly, this model, exact or not, is more accurate than the
train/whistle model.

"Phil Allison" wrote in message
...

"Porky"


** This little piggy cannot trot and chew rotten fruit at the same
time.



Oh, Phil is repeating himself now, too bad it's just as insipid this time as
it was the last.

"Phil Allison" wrote in message
...

"Porky"

The fact that I drove my big speakers with a 20Hz tone combined with
a
500Hz tone at a level that the online proponents of Doppler distortion
said
would produce audible Doppler shift,


** What level was that and WHO said so ????

It was from a website that one of the proponents of Doppler distortion
posted. The peak velocity of my woofer exceeded that of the woofer in their
experiment which meant I should have had a greater degree of Doppler
distortion that that shown in their experiment, but there was none. Perhaps
the original poster can repost the link, I haven't the time to go back and
look it up, thugh I did refer to it in my original post concerning my
experiment.

Porky wrote:


To the rest of the members of the various groups, I apologize for the
outburst, but this jerk started it and he clearly had it coming.

Problem is you gave him exactly what he was looking for.
Ignore the troll. Starve him.


Bob
--

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

A. Einstein

"Porky"

Randy, it appears to me that you're still using the train/whistle
model
as a basis for the self-evidence of your claim, and if that model applied
to
this case you would be entirely correct. However it doesn't apply to
loudspeakers producing complex waveforms.


** Pure gobbledegook.


The problem here is whether the sound source is actually moving relative
to the listener, when the source is a speaker being driven by a complex
waveform.


** The high frequency source is the one moving.


There are models that show .....


** Models are approximations to reality.


that the actual source of the sound is
a point or plane that lies approximately at the center of the motion
described by the cone ....


** Even using such a model, that approximation is true only for single
frequency operation.


If these models
are correct, then the source of the sound is not in motion relative to the
listener and therefore Doppler distortion does not and cannot exist in a
speaker.


** YOU are the one who is incorrect.


Certainly, this model, exact or not, is more accurate than the
train/whistle model.


** Not one bit - you are clearly an utter imbecile.




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

"Porky"

"Phil Allison"



** This little piggy cannot trot and chew rotten fruit at the same
time.



Oh, Phil is repeating himself now, too bad it's just as insipid this time
as
it was the last.


** Not one bit - you are clearly an utter imbecile.


Oink oink oink oink oikk .......



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

Porky wrote:


What he said. Is this the same Porky that I've argued with
about _so_ many things?



:-) Yep, I just had an attack of common sense before I started posting
again. I decided to try to contribute positively to the group and to forget
about any preconceived notions I may have had about group members. It seems
that after doing so, my opinions of many of you went up quite a bit, which
means that it was my misconceptions that were the problem. I apologize to
all for that.

Wow. You don't often encounter that. Well done and welcome.

Note that I'm not necessarily agreeing with you about Doppler distortion,
but I am noting that most of those arguing in its favor are doing so on the
basis of the train/whistle analogy which is an entirely different animal.
Any theories based on that model don't necessarily apply to a "speaker cone
driven by a single complex waveform" model. Unless someone can provide
concrete proof based on real world measurements or provide an argument based
on the "speaker cone driven by a single complex waveform" model, I'm still
on the fence but leaning toward your side.:-)

Well, everything you've offered is technically spot on. I
think you'll find the right conclusion.


Bob
--

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

A. Einstein

Randy Yates wrote:

Bob Cain writes:


Randy Yates wrote:


Not. Get a clue, people. Doppler is a *PHYSICAL PHENOMENOM* that
WILL happen whether or not you decide it can WHENEVER a sound wave
source and observer are moving relative to each other. Period. This
isn't open for debate.

Randy has spoken. Without one shread of a predictive theory. Odd,
that.


Have you ever been to Ethiopia, Bob? We might as well be debating whether
or not gravity exists there. I've never been - you've never been - so
we can't say experientially, so it's open for doubt, right?

Randy, do you really think that if this complex interaction
is real, there needn't be a mathematical expression which
describes the effect on any signal in a way that is subject
to experimental verification?


Bob
--

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

A. Einstein

"Porky"
"Phil Allison"



The fact that I drove my big speakers with a 20Hz tone combined
with
a 500Hz tone at a level that the online proponents of Doppler distortion
said would produce audible Doppler shift,


** What level was that and WHO said so ????

It was from a website that one of the proponents of Doppler distortion
posted.


** Get real - post the details.


The peak velocity of my woofer exceeded that of the woofer in their
experiment


** At only 20 Hz ???? Get real.


which meant I should have had a greater degree of Doppler
distortion that that shown in their experiment, but there was none.


** Not one poster here has said Doppler shift is readily audible from such
a test.

It has been said *repeatedly* that it will be swamped by
intermodulation effects.


Perhaps the original poster can repost the link, I haven't the time to go
back and
look it up,


** Liar.



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

Randy Yates wrote:

"Entire generating system." Now there's an ill-defined statement.

So thought Einstein when Bohr offered it in refutation of
one of his many challenges. :-)


Bob
--

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

A. Einstein

Randy Yates wrote:


Please explain to me why the wavelengths perceived by an observer
experiencing a time-varying velocity relative to the source will
not also experience a time-varying Doppler shift.

Because the air can carry the time varying signal.


Bob
--

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

A. Einstein

"Randy Yates" wrote in message
...
Bob Cain writes:

Ben Bradley wrote:


But seriously, for Bob and other anti-doppler-distortion folks, how
does cone-and-frame movement cause doppler while cone movement only
does not? What is it about the frame that causes doppler?

This is beginning to feel like an Einstein/Bohr debate. Not in the
capabilities of the participants but in the nature of it. :-)

My answer to this is that you must always consider the entire
generating system.

"Entire generating system." Now there's an ill-defined statement.

You must find the rest position of that entire
system. In the frame of reference of (attached to) that rest
position, there will be no "Doppler distortion."

In the frame of reference of the acoustic emitter,
there is no Doppler shift. That is certainly true.

The air is capable of carrying any time varying signal but not an
unvarying one. What it does in a frame of reference that is moving
with constant velocity relative to that rest position is Doppler shift
it. If the motion is varying in time it is linearly superimposed on
the signal being emitted.

Please explain to me why the wavelengths perceived by an observer
experiencing a time-varying velocity relative to the source will
not also experience a time-varying Doppler shift.
--

The simple answer is that while the cone's movement provides the energy
for the sound, there is a conversion of air motion to pressure waves (sound
waves) which does not occur within or on the cone's surface, thus the actual
sound source is not the speaker cone, it is the point or plane where the air
motion to pressure wave conversion takes place.

Here's a link that you tech folks can argue about:

http://www.pcavtech.com/techtalk/doppler/

"Bob Cain"
Porky wrote:


To the rest of the members of the various groups, I apologize for the
outburst, but this jerk started it and he clearly had it coming.

Problem is you gave him exactly what he was looking for.
Ignore the troll. Starve him.



** ROTFLMAO !!!

What the hell do you think Bob Cain is doing right now if not carrying on
the biggest, dumbest, most pathetic damn troll this NG has seen in years.

You are all having your legs pulled - right off !!





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

"Phil Allison" wrote in message
...

"Bob Cain"
Porky wrote:


To the rest of the members of the various groups, I apologize for
the
outburst, but this jerk started it and he clearly had it coming.

Problem is you gave him exactly what he was looking for.
Ignore the troll. Starve him.



** ROTFLMAO !!!

What the hell do you think Bob Cain is doing right now if not carrying on
the biggest, dumbest, most pathetic damn troll this NG has seen in years.



You are all having your legs pulled - right off !!





Phil, I believe that you are misspelling your name, it obviously should
be "Phool"!
What you're pulling on isn't a topic for discussion among decent folk...

"Porky" writes:
[...]
Please explain to me why the wavelengths perceived by an observer
experiencing a time-varying velocity relative to the source will
not also experience a time-varying Doppler shift.
--

The simple answer

It's OK, you can use big words and math with me. I'm a big boy
now.

is that while the cone's movement provides the energy
for the sound, there is a conversion of air motion to pressure waves (sound
waves) which does not occur within or on the cone's surface, thus the actual
sound source is not the speaker cone, it is the point or plane where the air
motion to pressure wave conversion takes place.

Accepting this assertion as true for the moment, why wouldn't the
position of this "point or plane" be a function of the position of the
cone? Thus, again, this point would move along with the low-frequency
energy.

Also, a) where did this theory of "air motion to pressure waves" come
from, and b)why did you wait some 20 or 30 posts before coming out
with this as your main basis for why Doppler does not occur?
--
% Randy Yates % "With time with what you've learned,
%% Fuquay-Varina, NC % they'll kiss the ground you walk
%%% 919-577-9882 % upon."
%%%% % '21st Century Man', *Time*, ELO
http://home.earthlink.net/~yatescr

"Randy Yates" wrote in message
...
"Porky" writes:
[...]
Please explain to me why the wavelengths perceived by an observer
experiencing a time-varying velocity relative to the source will
not also experience a time-varying Doppler shift.
--

The simple answer

It's OK, you can use big words and math with me. I'm a big boy
now.

is that while the cone's movement provides the energy
for the sound, there is a conversion of air motion to pressure waves
(sound
waves) which does not occur within or on the cone's surface, thus the
actual
sound source is not the speaker cone, it is the point or plane where the
air
motion to pressure wave conversion takes place.

Accepting this assertion as true for the moment, why wouldn't the
position of this "point or plane" be a function of the position of the
cone? Thus, again, this point would move along with the low-frequency
energy.

That's where it gets tricky, but I've long seen it referred to as a
"point" source or a "planar" source, and for whatever reason it's treated as
a non-moving stable source. I believe that it has to do with the air's mass
and inertia, but as I said, the actual physics will have to be figured out
by those with a higher education than I have. This actually goes back at
least as far as the '60's and possibly much earlier. That's the reason I
didn't advance it sooner, it just didn't occur to me. I was just following
the reasoning that the speaker cone actually generated the sound, until it
finally occurred to me that it doesn't, whatever is producing the actual
sound waves has to be moving at the speed of sound to impart the necessary
pressure wave, and this is the interface where molecular motion is converted
to pressure waves. Think about it, if the speaker pushes a volume of air
forward, it will be moving at the same speed as the cone that imparted the
motion, and it won't be sound, it will be a slowly moving volume of air.
When the molecules in that volume of air meet other molecules, the slow
motion of molecules is converted into a high velocity pressure wave where it
is the pressure wave that is moving and not the air itself, just like an
ocean wave. This is a dynamic process and the back and forth motion of the
cone has nothing to do with it as far as the sound's source point is
concerned. I can see how it happens and understand it quite well, but I
simply haven't got the math or physics background to do the equations.

Also, a) where did this theory of "air motion to pressure waves" come
from, and b)why did you wait some 20 or 30 posts before coming out
with this as your main basis for why Doppler does not occur?

As I said, it just occurred to me that the speaker cone doesn't produce
the sound, the air does. It's been a long time since I'd thought about it
because the model goes back a long way. Before this, I was on the fence,
though I was leaning toward the "no Doppler" side, I suppose because this
was rolling around in my subconscience. I knew that there was something
wrong with the train/whistle model, and I was thinking all along that it was
the multiple simple sources vs the single complex source, but that wasn't
it, this was.
"The sound wave may be considered as holographic in nature, and just like a
visual hologram doesn't appear on the surface of the holographic plate,
neither does the sound wave originate on the surface of the speaker cone." I
have no idea whom I'm quoting, but I remember the quote from some text or
other I read quite a few years ago. The words may not be exact, but the gist
is the same.