Because there is a real difference. Air can't carry the DC
component of velocity but it can carry any time varying
component.

Yes, it can. It's called a breeze.

ruffrecords writes:

Randy Yates wrote:
ruffrecords writes:


Randy Yates wrote:

ruffrecords writes:


If both systems are linear then they will
work in an identical manner.

That statement is absolutely correct, just as "If I am pregnant,
then I am a female." is absolutely correct.

And your point is what?
Are you REALLY this clueless and/or stupid? I give up. You apparently

do not have the facilities to reason rationally.


At least I have better manners than you.

You deserve every bit of this public ridicule. This is not a
case of bad manners, but rather a proper response.

It would be one thing to have come with an attitude of inquiry,
but you come into the discussion with blatant challenges based
on little knowledge and without the facilities to rationally
discuss.

You're like a gun-fighter with an empty cash of bullets and a broken
arm who accosts an enemy gunslinger multiple times and then whines when
he gets shot. Don't be stupid. Approach with a right attitude.
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
, 919-472-1124

On Tue, 17 Aug 2004 11:25:12 -0700, Bob Cain
wrote:

Because there is a real difference. Air can't carry the DC
component of velocity but it can carry any time varying
component.

I guess DC offset in air is barometric pressure?

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect

"ruffrecords" wrote in message

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

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




Looks good to me. Plenty of evidence of harmonic distortion (casued
by non-linearites

Agreed.

and no evidence of 50Hz sidebands arounf the 4KHz signal.

What do you call the spikes around the 4,025 Hz carrier in, for example

http://www.pcavtech.com/techtalk/dop...1-1-1+10dB.gif

Doppler distortion is dead.

Nope. If I bandpass filter out everything from 3,800 Hz to 4.200 Hz and then
clip it into a near-perfect square wave, of course any AM is history. There
then remain 4 very clear sidebands at 50 Hz intervals around the carrier.

"Laurence Payne" wrote in
message
On Tue, 17 Aug 2004 11:25:12 -0700, Bob Cain
wrote:

Because there is a real difference. Air can't carry the DC
component of velocity but it can carry any time varying
component.

I guess DC offset in air is barometric pressure?

I do believe.

Arny Krueger wrote:


I do believe it is in Halliday and Resnick, even though it has been decades
since I read it there.

It's also in the JAES papers that have now been cited several times in the
various discussions on the various newsgroups.

Since you have those papers, Arny, is there any chance that
you could locate the expression and post it?


Bob
--

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

A. Einstein

Arny Krueger wrote:

It seems like I'm the only one in this group with ready access to the JAES
which may be understandable. But Halliday and Resnick should be in a jillion
different libraries. There don't seem to be a lot of people here who have
actually taken first year college physics, it seems.

I don't even need to make a trip to the Santa Cruz, CA,
library to know that it isn't in their stacks.

Arny, since you are the one with ready access to this
information please share it.


Bob
--

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

A. Einstein

Randy Yates wrote:
ruffrecords writes:


Randy Yates wrote:

ruffrecords writes:


If both systems are linear then they will
work in an identical manner.

That statement is absolutely correct, just as "If I am pregnant,
then I am a female." is absolutely correct.

And your point is what?


Are you REALLY this clueless and/or stupid? I give up. You apparently
do not have the facilities to reason rationally.

At least I have better manners than you.

Ian

Ben Bradley wrote:


I suspect Bob knows it as well as you do, but he's just missing it
and has some other idea in mind when it comes to a speaker cone.

I have succinctly and precisely stated the physics on which
my view rests. The logic of that argument has not been
refuted by anyone. Have a go at it.


Bob
--

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

A. Einstein

William Sommerwerck wrote:

Bob Cain has no interest in the facts -- he is having a giant hoot
at our expense.


I don't think so. It's rather that Bob is open-mined enough to ask for other
people's opinions -- but when he gets a response that doesn't fit with his
opinion, he doesn't want to accept it. We're all like that at one time or
another.

I don't give a rat's ass about opinion. Show me the science
reduced as it must be to an expression which predicts the
consequences on any waveform and which can be exprimentally
verified.


Bob
--

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

A. Einstein

Arny Krueger wrote:

"Bob Cain" wrote in message


Randy Yates wrote:


Proof by assertion?

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


Even in the presence of experimental confirmation?

Your experiments confirm nothing. They don't eliminate
sources of false positives.


The predictive theory is as near as the nearest stack of JAES papers, which
have been cited here a number of times.

You've got 'em. Please produce it. Again, it is incumbent
on the one claiming a phenomenon to prove its existence.


Bob
--

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

A. Einstein

PenguiN wrote:


As you've agreed, if the sound source is in motion, the system is no
longer linear due to the speed at which sound travels in air, and can
produce doppler distortion (for example, if I were to hold a speaker
in my hands and run back and forth towards and away from you, there
would be doppler, right?).

No. It would add that motion to the wave it produces in a
linear fashion. Since it is not possible to produce a wave
in air from a constant motion relative to it, that motion
must be accomodated by what is called Doppler shift. It is
utterly wrong to extend the Doppler shift concept to an
oscilating source. It is purely a constant motion phenomenon.


Bob
--

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

A. Einstein

Arny Krueger wrote:

"Bob Cain" wrote in message


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.


GMAB. He cited Halliday and Resnick. I cited the JAES. Someone else cited
the JAES.

BTW Halliday and Resnick ride on:

http://jws-edcv.wiley.com/college/bc...74____,00.html

Please find the mathematical basis for your theory in it.


Bob
--

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

A. Einstein

Arny Krueger wrote:

"Bob Cain" wrote in message


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.


That could be both true and confusing, no?

No.


**** you, and I say that with all due respect. The system
here is everything from the face of the piston on out.


Out how far? Until we get to the receiver, there is no Doppler distortion
from that piston. Once we get to the receiver, there is Doppler distortion.
But judged all by itself fixed in space, the receiver can be
distortion-free.

Not even sure what you are saying here, sorry.



Nothing that occurs before that can be contributory and must
be eliminated in some way from any experiment designed to
catch Doppler at work.


It would be nice to eliminate that, but in the real world of acoustic
measurements...

I've offered one way to eliminate most of it.



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.


Asked and answered, but it takes a little reading in standard references.

Please do so and provide theoretical support of your
proposed phenomenon. As always in science, that is on you.


I sincerely hope no one will say that it isn't
required because you see evidence of frequency modulation.


Where else might that FM come from?

The system that preceeds the piston/air interface.


Bob
--

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

A. Einstein

I don't give a rat's ass about opinion. Show me the science
reduced as it must be to an expression which predicts the
consequences on any waveform and which can be exprimentally
verified.

I'm not being snide when I ask, why don't you work it out for yourself? It's not
horribly complex.

All you need is to apply the formula for the Doppler shift of sound to the
low-frequency excursions of the cone.

Arny Krueger wrote:

"Porky" wrote in message



I think you're right, Bob, that certainly seems logical to me. If it
is Doppler distortion, the tone should be vary in a continuous warble
from -50Hz to +50Hz because the woofer's velocity is continuously
changing.


The FFT plots are snapshots of a kind, but they are also time-exposures. 1
million points at 96 KHz is about 11 seconds worth of data. It is all
averaged together in those pictures.

If one uses a low enough modulating frequency, and a small enough sample
set, snapshots with a faster effective exposure times result.

One can then actually can see the carrier warbling. It will show up at
different frequencies at different times in a sucession of snapshots.

However, with a long exposure you see the results averaging of about 550
cycles of the 50 Hz tone.

That's some excellent hand waving, Arny. But it doesn't
explain where all those other frequencies disappear to.
There's nothing in an FFT of one cycle of the low frequency
that would average them away. That's nonsense.


Bob
--

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

A. Einstein

Arny Krueger wrote:


This is not debatable. Find a rigorous definition of linearity.


I think I just posted one.

I'll be on the lookout for that posting.


There are in fact several different definitions of nonlinear distortion,

If you say so but there is only one accepted definition of
linearity and it involves those pesky eigenfunctions and
eigenvalues. Stated in the vernacular it says that a linear
system is one in which no frequencies not in the input can
appear in the output for any possible input signal. All
other propeties of linear systems derive from that.


Bob
--

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

A. Einstein

Laurence Payne wrote:

On Tue, 17 Aug 2004 11:25:12 -0700, Bob Cain
wrote:


Because there is a real difference. Air can't carry the DC
component of velocity but it can carry any time varying
component.


I guess DC offset in air is barometric pressure?

Right, and a constrained piston can't change it.


Bob
--

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

A. Einstein

Randy Yates wrote:

Are you REALLY this clueless and/or stupid? I give up. You apparently
do not have the facilities to reason rationally.


Are you the same Randy Yates that is a regular on comp.dsp?


Bob
--

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

A. Einstein

On Tue, 17 Aug 2004 13:53:24 -0700, Bob Cain
wrote:



Your experiments confirm nothing. They don't eliminate
sources of false positives.



Let me explain again my processing of the pcavtech data.

I demodulated the FM (rather well, I think). This makes my data
immune to any AM sidebands. I then selected the component of this
demodulated signal at 50 Hz. This makes it immune to all the other
frequency components present. I did this both for the 4025Hz carrier
(shown) and the 1000Hz carrier (not shown at the time I posted
"bingo") both of which were frequency modulated by the large 50Hz
component of the test data. The phase deviation in radians is
numerically equal to the modulation index and in the case of 50Hz
modulating frequency you can convert this to frequency deviation by
multiplying the modulation index by 50. This was plotted as Y values
and obviously involved a lot of processing and is a very indirect way
of measuring distance. (phase angle/2*PI)*wavelength)

The X coordinates were simply calculated by taking the estimate of the
linear displacement of the speaker cone at 10 Volts RMS drive given by
Arny and assuming that the displacement was linear with Voltage.
This was converted to the fraction of the wavelength at 4025 Hz and
1000Hz this represented and converted to radians.

The X and Y values were then plotted without any further assumptions.

Both the the 4025Hz and 1000Hz data follow the same "curve" (with
some scatter) and that curve is the straight line X=Y.

Now when you can think of some distortion by the amplifier/speaker
that follows *that* maths, get back to me.

Bob Cain wrote:
Laurence Payne wrote:

On Tue, 17 Aug 2004 11:25:12 -0700, Bob Cain
wrote:

Because there is a real difference. Air can't carry the DC
component of velocity but it can carry any time varying
component.


I guess DC offset in air is barometric pressure?

Right, and a constrained piston can't change it.

No, it should change it a little bit. Of course, the ratio between the
volume of the box behind the piston and the volume of the earth's atmosphere
is very small. But it's nonzero!
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bob Cain writes:

Randy Yates wrote:

Are you REALLY this clueless and/or stupid? I give up. You apparently
do not have the facilities to reason rationally.


Are you the same Randy Yates that is a regular on comp.dsp?

You're damn right I am, Bob.

My respect for you and others here has plummetted. I hear you repeatedly
asking folks to spoon-feed you at the most fundamental level - so much
so you can't seem to lift a finger to check out a reference. Do you
live at the North Pole? Why can't you go to the library and check out
a physics book? Are you crippled?

Porky seems to be pulling reasons out of a hat. ruffrecords can't seem
to reason.

As I said earlier in another post, my response would be different if
folks came at this from a more humble perspective of rational inquiry
and discussion.

The problem with your approach, Bob, is that you are challenging
a well-proven principle with little or no reason to back it up. Why
WOULDN'T a speaker act as a moving platform? Porky proffered a
strange theory at least - you have offered none that I recall. At
some point calling reasonable assumptions into question is irrational
and you begin searching for the holy grail when the more rational
explanation is the one that is simplest.

You stand hard on the "theory" of science as requiring "proof." I got
news for ya' - scientific "proof" isn't all it's cracked up to
be. Invariably, at some level, there will be assumptions that are
made. Even in mathematics, proofs are based, ultimately, on axioms,
and those axioms are essentially just assumptions about what is true.

Keep in mind that this is a mathematics and electrical engineering
graduate speaking here.

Essentially, our laws and theories are ones that agree with our
experience and our universe as best we can model at the moment. There
is no "proof" of any of them.
--
Randy Yates
Sony Ericsson Mobile Communications
Research Triangle Park, NC, USA
, 919-472-1124

"Bob Cain" wrote in message

Arny Krueger wrote:


I do believe it is in Halliday and Resnick, even though it has been
decades since I read it there.

It's also in the JAES papers that have now been cited several times
in the various discussions on the various newsgroups.

Since you have those papers, Arny, is there any chance that
you could locate the expression and post it?

Here's one of many which together include various presumptions about
radiation pattern, etc.

AES preprint 1844, October 1981

Authors: Allison and Villchur

DFT = 0.019 Al f2

DFT = FM distortion factor (the square root of the ratio of power in the
sidebands to the total power of the f2 signal and sidebands, expressed as a
percent or total radiated power, presuming the speaker is a hemispherical
radiator.

A1 = center-to-peak cone excursion at the modulating frequency (in inches),

f2 = FM modulated frequency,

"Bob Cain" wrote in message

Arny Krueger wrote:

"Bob Cain" wrote in message


Randy Yates wrote:


Proof by assertion?

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


Even in the presence of experimental confirmation?

Your experiments confirm nothing. They don't eliminate
sources of false positives.

Not true.

The predictive theory is as near as the nearest stack of JAES
papers, which have been cited here a number of times.

You've got 'em. Please produce it. Again, it is incumbent
on the one claiming a phenomenon to prove its existence.

Actually, I produced it several weeks ago in this post:

http://www.google.com/groups?selm=Y7...%40comcast.com

"Bob Cain" wrote in message


That's some excellent hand waving, Arny. But it doesn't
explain where all those other frequencies disappear to.
There's nothing in an FFT of one cycle of the low frequency
that would average them away. That's nonsense.

Since the modulating frequency is the low frequency note, a FFT that covers
an entire low frequency cycle would include instances of all possible
frequencies that the sidebands might have.

This begs the question as to what would happen if one measured the position
of the sidebands in two adjacent 0.01 second periods.

If the sidebands are in fact in motion @50 Hz, then their frequencies can be
expected to differ most of the time. Actual measurements of an actual
measured wave, processed to vastly reduce all AM distortion, does show this
effect.

If in contrast the positions of the sidebands in two adjacent 0.02 second
periods are measured, they should be the same, and this is what one
observes.

0.01 seconds corresponds to 410 samples at 44.1 KHz, so in this experiment,
the FFT should be based on 410 samples or less to avoid overlapping. 512
sample FFTs will overlap a bit, but are required to make the sideband
structure clear enough to comment on.

Bob Cain wrote:



Laurence Payne wrote:

On Tue, 17 Aug 2004 11:25:12 -0700, Bob Cain
wrote:


Because there is a real difference. Air can't carry the DC component
of velocity but it can carry any time varying component.



I guess DC offset in air is barometric pressure?


Right, and a constrained piston can't change it.

Drop the "constrained" qualifier.


Bob
--

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

A. Einstein

Randy Yates wrote:


You deserve every bit of this public ridicule. This is not a
case of bad manners, but rather a proper response.

It would be one thing to have come with an attitude of inquiry,
but you come into the discussion with blatant challenges based
on little knowledge and without the facilities to rationally
discuss.

You're like a gun-fighter with an empty cash of bullets and a broken
arm who accosts an enemy gunslinger multiple times and then whines when
he gets shot. Don't be stupid. Approach with a right attitude.

Randy, when it comes time for you to eat those nasty words,
can I watch?


Bob
--

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

A. Einstein

Randy Yates wrote:

My respect for you and others here has plummetted.

I'll survive.

I hear you repeatedly
asking folks to spoon-feed you at the most fundamental level -

Hmmm, I feel like I'm the one spoon-feeding fundamentals to
y'all.

so much
so you can't seem to lift a finger to check out a reference.

I simple ask people to prove their assertions as I have
attempted to prove mine.

Do you
live at the North Pole? Why can't you go to the library and check out
a physics book? Are you crippled?

The proof is on the one asserting the phenomenon. I am
simply not going to waste time searching for something that
I know doesn't exist.


Porky seems to be pulling reasons out of a hat. ruffrecords can't seem
to reason.

Translation: he doesn't agree with you.


As I said earlier in another post, my response would be different if
folks came at this from a more humble perspective of rational inquiry
and discussion.d

And I haven't? You are the one that's blind and deaf.


The problem with your approach, Bob, is that you are challenging
a well-proven principle with little or no reason to back it up.

On the contary, I am asking those asserting it to prove it's
existence with a general, predictive, mathematical theory.

Why
WOULDN'T a speaker act as a moving platform?

I've given numerous physical reasons the behavior you expect
can't and won't happen and you have not even attempted to
find a flaw.

Porky proffered a
strange theory at least - you have offered none that I recall.

You don't need a theory for the non-existence of a
phenomenon. It's the other way around. I've shown how
existing theory doesn't allow for it and I don't think you
can say I haven't. Where were your responses to those
illustrations if they were so wrong?

At
some point calling reasonable assumptions into question is irrational
and you begin searching for the holy grail when the more rational
explanation is the one that is simplest.

Show it to me then. Give me the expression that describes
your pet theory in detail. Without it there is nothing to
discuss.


You stand hard on the "theory" of science as requiring "proof." I got
news for ya' - scientific "proof" isn't all it's cracked up to
be.

Gimme a break. We are talking about a simple physical
phenomenon here, where is the physics?

Invariably, at some level, there will be assumptions that are
made. Even in mathematics, proofs are based, ultimately, on axioms,
and those axioms are essentially just assumptions about what is true.

"Doppler distortion" is an axiom only in your mind and the
only place you can find refuge from the requirement to prove it.


Keep in mind that this is a mathematics and electrical engineering
graduate speaking here.

Then you should be well capable of producing the rigorous
theoretical basis for this yourself.

Electrical Engineering and Engineering Physics here.
University of Illinois, Urbana campus.


Essentially, our laws and theories are ones that agree with our
experience and our universe as best we can model at the moment. There
is no "proof" of any of them.

How can it be that such an "obvious" physical phenomenon
defies rigorous description. That's simply absurd.


Bob
--

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

A. Einstein

Arny Krueger wrote:

"Bob Cain" wrote in message


Arny Krueger wrote:



I do believe it is in Halliday and Resnick, even though it has been
decades since I read it there.

It's also in the JAES papers that have now been cited several times
in the various discussions on the various newsgroups.

Since you have those papers, Arny, is there any chance that
you could locate the expression and post it?


Here's one of many which together include various presumptions about
radiation pattern, etc.

AES preprint 1844, October 1981

Authors: Allison and Villchur

DFT = 0.019 Al f2

DFT = FM distortion factor (the square root of the ratio of power in the
sidebands to the total power of the f2 signal and sidebands, expressed as a
percent or total radiated power, presuming the speaker is a hemispherical
radiator.

A1 = center-to-peak cone excursion at the modulating frequency (in inches),

f2 = FM modulated frequency,

Arny, don't you know the difference between the statement of
a particular case, without justification, and a rigorous theory?


Bob
--

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

A. Einstein

William Sommerwerck wrote:

I don't give a rat's ass about opinion. Show me the science
reduced as it must be to an expression which predicts the
consequences on any waveform and which can be exprimentally
verified.


I'm not being snide when I ask, why don't you work it out for yourself? It's not
horribly complex.

You just don't get it. Any attempt to do that from first
principles simply flounders. It can't be done.

All you need is to apply the formula for the Doppler shift of sound to the
low-frequency excursions of the cone.

Write it out then.


Bob
--

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

A. Einstein

Arny Krueger wrote:



The predictive theory is as near as the nearest stack of JAES
papers, which have been cited here a number of times.


You've got 'em. Please produce it. Again, it is incumbent
on the one claiming a phenomenon to prove its existence.


Actually, I produced it several weeks ago in this post:

http://www.google.com/groups?selm=Y7...%40comcast.com

If you really believe that even begins to approach anything
like a demonstrable or refutable theory there just isn't
common ground for a discussion.

I'll put it simple: post an equation that describes the
sound pressure at a reciever as a function of the velocity
of a piston. An equation that can be applied to any signal.
There certainly is such an equation, let's see one that
produces a verifiable spectrum, with the proper magnitudes,
for "Doppler distortion."


Bob
--

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

A. Einstein

"ruffrecords"
Phil Allison wrote:

To produce FM there needs to be a non-linearity.

Not really. A nonlinearity produces AM.

Yes really. It is exactly how a mixer works in a receiver. The non
linearity produces sum and difference frequencies.


** Which is characteristic of AM - you jerk.



Both FM and AM have sidebands (sum and difference frequencies). A
non-linearity can produce a number of effects, like harmonics for
example, not just AM.


** But simple circuit non linearity *** cannot*** produce FM.

That requires another mechanism.



And if you continue to reply with personal remarks I'll simply ignore you.



** You are just another demented pommy ****wit.


I do so hope that does the job.




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

PenguiN wrote:


Uhm, no. Frequency modulation does *not* produce a flat tabletop.

http://www2.sfu.ca/sonic-studio/hand...odulation.html

Perhaps you both should review your basic signals & systems course
before continuing this discussion?

Agreed. I still don't understand why it wouldn't display
all the frequencies between the extrema equally but I'll
take your word for it. I don't know modulation theory and
this is obviously a failure of intuition.

My real argument isn't about the form or spectrum of the
modulation, it's about its existance. My question was a
tangent.


Bob
--

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

A. Einstein

I'm not being snide when I ask, why don't you work it out for yourself?
It's not horribly complex.

You just don't get it. Any attempt to do that from first
principles simply flounders. It can't be done.

Sure it can.


All you need is to apply the formula for the Doppler shift
of sound to the low-frequency excursions of the cone.

Write it out then.

Do it yourself, Bob. This is trivial, high-school algebra. It does not require
fancy math of any sort.

The way you learn things -- that is, understand them -- is by doing them.

William Sommerwerck wrote:

All you need is to apply the formula for the Doppler shift
of sound to the low-frequency excursions of the cone.

Write it out then.

Do it yourself, Bob. This is trivial, high-school algebra. It does not require
fancy math of any sort.

Actually, to do it in the time domain, it takes a Bessel function. The
reference to Terman is an excellent one.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Bob Cain writes:
[...]
Why
WOULDN'T a speaker act as a moving platform?

I've given numerous physical reasons the behavior you expect can't and
won't happen [...]

1) It is not the behavior I "expect" - it is the behavior predicted by
a well-known physical law.

2) State your reason here and now - give it your best shot. Or else drop it.
--
% Randy Yates % "Midnight, on the water...
%% Fuquay-Varina, NC % I saw... the ocean's daughter."
%%% 919-577-9882 % 'Can't Get It Out Of My Head'
%%%% % *El Dorado*, Electric Light Orchestra
http://home.earthlink.net/~yatescr

"Bob Cain" wrote in message

Arny Krueger wrote:

"Bob Cain" wrote in message


Arny Krueger wrote:



I do believe it is in Halliday and Resnick, even though it has been
decades since I read it there.

It's also in the JAES papers that have now been cited several times
in the various discussions on the various newsgroups.

Since you have those papers, Arny, is there any chance that
you could locate the expression and post it?


Here's one of many which together include various presumptions about
radiation pattern, etc.

AES preprint 1844, October 1981

Authors: Allison and Villchur

DFT = 0.019 Al f2

DFT = FM distortion factor (the square root of the ratio of power
in the sidebands to the total power of the f2 signal and sidebands,
expressed as a percent or total radiated power, presuming the
speaker is a hemispherical radiator.

A1 = center-to-peak cone excursion at the modulating frequency (in
inches), f2 = FM modulated frequency,

Arny, don't you know the difference between the statement of
a particular case, without justification, and a rigorous theory?

You said post an expression, not lay out the detailed theory. If you can't
keep your stories straight, there's no need for me to honor your requests in
the future.

"Bob Cain" wrote in message

Arny Krueger wrote:



The predictive theory is as near as the nearest stack of JAES
papers, which have been cited here a number of times.


You've got 'em. Please produce it. Again, it is incumbent
on the one claiming a phenomenon to prove its existence.


Actually, I produced it several weeks ago in this post:

http://www.google.com/groups?selm=Y7...%40comcast.com

If you really believe that even begins to approach anything
like a demonstrable or refutable theory there just isn't
common ground for a discussion.

Beggars can't be choosers.

"Phil Allison" wrote in message
...

"Ben Bradley"

I suspect Bob knows it as well as you do, but he's just missing it
and has some other idea in mind when it comes to a speaker cone.



** We are all the victims of a pathetic NG troll's wet dream and a
hoax.

I think you have anger issues.

Bob Cain has no interest in the facts - he is having a giant hoot at
our
expense.

Hardly. Bob is a good guy searching for an answer he can't determine
himself. He cannot prove a negative, so absent a mathematical proof
otherwise, he is free to deny its existence. We can all perform mind
experiments, but that always doesn't mean they are right. It took a few
thousand years for someone to disprove the intuitive mind experiment that if
a car is traveling at 0.99c and turns on its headlights, the light is now
traveling 1.99c (Note: I know they didn't have cars 2,000 years ago). I'm
not saying Bob is Einstein, but Einstein at least proved his point with
mathematics that have held up to testing.

Bob can correct me here, but from where I sit, Bob does not deny the Doppler
shift. He completely accepts the formula fo = fs . (v - vo) / (v - vs). What
he does not accept is that you can insert the speaker diaphragm's movement
as vs. He accepts that you can put the speaker on the train and predict the
Doppler shift with the above formula as does everyone he's arguing with.

But here's the kicker: Either the above formula is wrong, there is no
Doppler Distortion, or somebody left out an assumption somewhere. Why?
Because the formula does not take into consideration the movement of the
diaphragm. If the source and observer are not moving, there is no Doppler
shift, right? But according to the proponents of Doppler Distortion, there
*is* a shift. Everything that creates sound moves in some way. So why hasn't
someone updated that formula?

The Doppler formula ignores the movement of the source AS IT CREATES THE
WAVES. So, if the source were some huge vibrating wire that moved a couple
of feet as it created the wave, the above formula would not account for the
wire moving.

So, Bob's position is quite simple: Show a formula that will predict what
the Doppler shift will be based on the movement of the source itself when
creating the wave, then perform an experiment that shows those results. I'm
thinking he'd settle for the former.

So, it's easy to find the formula that shows how Doppler works (train
example) without taking into consideration the movement of the plane of the
source that is creating the sound. I've seen numerous sites talk about
Doppler Distortion, but I've yet to uncover one that shows the actual
mathematical representation.

Somebody post this formula so we can all go to bed.


Only complete fools keep going when they are being conned.

Like I said...

"Mark" wrote in message
om...

Using 344.3 m/sec for the speed of sound and the Doppler equations
found he

http://www.mathpages.com/rr/s2-04/2-04.htm

Help this poor uneducated soul, will ya? The formula you are referencing
states that if the source is at rest, there is no apparent frequency shift.
It is inherently impossible for the source to be at rest *and* create a
sound wave. After all, sound waves are compression waves, right?

So, what's the deal? Why does this formula ignore the movement of the source
in creating the wave?

I'm no expert in this field by any means, so spell it out for me, will ya? I
have no textbooks here at home. I just have the web, and I've failed to find
a formula that takes into account the movement of the source as it creates
the wave.