Eddie Runner wrote:

In a great try to divert the issue:

Nousaine wrote:

So Eddie; what is your definition of a standing wave? Two sounds at the
same
ftequency traveling in opposite directions? Isn't that it? Or have you
changed
you defintion?

I havent changed my definition but YOU need to CHANGE YOURS!

My definition of a standing wave is two (OR MORE) waves that
interfere with each other in a way that nodes or antinodes appear
to stand still.

But you made a great issue of different directions, did you not? And you
completely ignore that Baranek put your arguments to task as well.

(antinodes are points of higher spl and nodes are
points of lower spl)

These nodes and anti nodes are caused by the two (or more) waves
bouncing or coming from different sources, they create the nodes and
antinodes because there are spots that the second (or more) wave is
in phase or out of phase ALWAYS at that spot and at that frequency.

Constant unchanging phase relationship between two or more sounds
creates the nodes and antinodes....

For instance, at a distance from a reflection of 1/4 wave, the reflected
wave will come back to the speaker at exactly 180degrees out of phase,
this point at the speaker is a NODE....There will be a cancelation here!

OK; there's a 20 Hz tone (one in your sweep) with a 50-ft wavelength; 1/4 wave
= 12.5 feet. So exactly HOW did the woofer cancellation at your microphone
decide that it would reduce it's level exactly as much as when in was working
at 50 Hz?

Pretty smart woofer. Or maybe it wasn't smart at all and was working for
another master.


As the first wave goes through its cycle the reflected wave goes through
its cycle just the same, so if the first wave is 45degrees the second wave
is ALWAYS 180degrees different!! ALWAYS!!

Assuming you're working in the realm of known physics; exactly how does it know
how to do this with EVERY low frequency given the identical spatial location?

Perhaps it just does this with regard to regular physics and below the lowest
axial mode just says "hell with it" I'm just going to pressurize this small
space.

And, actually, it has no choice. It's a speaker and does whatever the heck it
can.


Or if the distance is different it could be IN PHASE just as well.

Normally, in your narrow definition of a standing wave you can
walk through the standing wave and measure the nodes and antinodes
with an SPL meter.... This happens because the waves are crossing
each other... (going in opposite directions)

Really? Then how does this happen with your single-all cartoon? In your
cancellation region the waves are all traveling in the same direction. How does
this work? I know the answer to this but Eddie doesn't. That's because he's
never conducted experiments that confirm his off-kilter ideas until prompted.

Until pushed. Now he's saddled with ......results that he's squiggling to make
his point;

But he cannot walk away from the "cancellation" idea; either his cartoon is
dreadfully wrong OR he has to find an "all-frequency" model.


But in this case, once the wave has bounced back and joins the
incedent wave (wave direct from speaker) then there is a node
created that reaches all the way into the listeing area... (less spl)

Tom, come out of the Jr High school mindset of the common
example of a standing wave where the wave can easiily be seen
in the clear tube as it moves the little cork particles... Understand
WHY these standing waves occur and what the components of
them are individually and see how they can have more complex
relationships....

Waves dont have to be moving in opposite directions, they
can!

So "now" you say that a standing wave DOESN'T have to have waves traveling in
the opposite direction. I guess you HAVE changed your defintition.

Why do your physics change over time?


Or they can cross each other like two pebbles in a pond,
or they can run right along with each other for a short distance
or a long distance... Any of these can cause nodes and antinodes...

Hmmmm..... after your hard arguments to the contrary. I'd like a given story
where you stick to it. Isn't it wonderful to slide-along and yet call everybody
else a slider. Hey Eddie; get a story and stick to it, and look in the mirror
once in a while



I have done some pretty extensive study of reflections and standing
waves.

I have built many variations of the tube and cork, we were
actually going to make one for our sound board so customers could
play with the oscillator dial and watch the cork particles jump.

I have built small and large scale models of how standing waves
occur with different colored string and the 1-360 degrees marked
on the string.

I used to have a little pink noise demonstration using a Janzen
electrostatic panel and a moveable wood reflector behind it, it
showed a nice hump and dip on the RTA when you moved the
reflector closer or further from the back of the electrostat (the
Janzen panels are bi-polar radiators by the way)...

I have found your average speaker guy has only a limited
knowledge of the effects of reflections and standing waves, the
subject is only lightly covered in the physics books and speaker
books... Much of the printed information is not agreed upon
in all the texts, therefor I have gone to much trouble to verify
myself what I wanted to know about this subject.

Great; why then,, do you hold these ridiculous ideas that are contrary to
high-school physics?

And as you may remember from last time we brought books into
the arguements I DO HAVE QUITE A REFERENCE LIBRARY! ;-)
http://www.installer.com/tech/baranek.html

Eddie Runner

Great; read some of them when you get a chance. Start with Baranek. Not
banacek, or something similar as you once tried to posture.