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PostPosted: Sat Dec 19, 2020 4:39 pm 
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I stumbled upon this while surfing the web the other night and thought it was worth sharing. It may already have been posted here but I don't have the foggiest idea what term to use to search and see if is has so if it's already been posted please forgive me!

This was on Becker's whistle home page at the bottom.

Click on this link to see the GIF in motion:
http://www.beckerwhistles.com/uploads/1 ... e_orig.gif


Still image:
Image


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PostPosted: Sat Dec 19, 2020 5:48 pm 
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Seeing the air stream flow go up and down makes me wonder if the frequency of that vertical fluctuation is a match for the frequency of the note being played. Perhaps the note heard is controlled by other factors along the length of the tube. Fascinating!


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PostPosted: Sat Dec 19, 2020 6:13 pm 
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RoberTunes wrote:
Seeing the air stream flow go up and down makes me wonder if the frequency of that vertical fluctuation is a match for the frequency of the note being played. Perhaps the note heard is controlled by other factors along the length of the tube. Fascinating!


I'm no expert but I think you are right that the higher the note the more up and down cycles per second. I'm guessing the distance from the air window to the each hole is the main factor along with the diameter of the bore is causing the air stream to fluctuate faster or slower. (And the size of the hole too.)


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PostPosted: Sat Dec 19, 2020 6:39 pm 
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That's really cool!

I knew in theory that's how it worked, but it's cool to see.

Not sure but I think I saw a video of a fluteplayer's airstream doing that, I think they had the fluteplayer take a drag on a cigarette or something.

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PostPosted: Sat Dec 19, 2020 8:20 pm 
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The link below has a nice explanation of how the sound production mechanism, bore and tone holes
interact to determine the frequency of oscillation and hence the note produced by a whistle (or
recorder). It also provides some more information about where the gif in the original post came
from.

http://www.flute-a-bec.com/acoustiquegb.html


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PostPosted: Sat Dec 19, 2020 8:28 pm 
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I noticed that the lion's share of the air flow oscillated above the labium. Any of you makers have any insights for us about that?

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PostPosted: Sat Dec 19, 2020 11:05 pm 
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Nanohedron wrote:
I noticed that the lion's share of the air flow oscillated above the labium. Any of you makers have any insights for us about that?


Whistles/flutes only sound a note once the air inside the bore is resonating. The length and shape of the bore, combined with various other properties such
as air temperature, humidity, etc, determine the frequency at which it resonates, which determines the note produced. It takes some input of energy to get the
resonance going, and there are energy losses due to friction, etc, so it takes some continuing input of energy to sustain the resonance as well. But if a large volume
of air was blown into, and through, the bore, it would disrupt the resonating air column, which would result in the note cutting out.

When a player blows across the window (or embouchure in the case of a flute), with the edge of the air stream just hitting a splitting edge, it serves as a source of
energy that can be tapped into periodically in order to offset the losses due to friction. The pulses of energy that momentarily/periodically enter the bore, do so in
sync with the oscillation of the air inside the bore and boost its energy just enough to sustain the state of resonance. In fact, you could think of the pressure oscillations
inside the bore as contributing to pulling that air jet down into the bore periodically, almost as if the resonating air column was tapping into the energy source.

So, basically, the challenge is to hit the balance point just right so that enough energy goes into that oscillating air column to sustain the resonance, but
not so much as to disrupt it. This is why small adjustments in the wind way, that affect how the air hits the labium, can cause a whistle to not sound at all.
The air flow is either too low, in which case too much air goes inside the bore and disrupts the resonance, or it is too high, in which case there is not enough
energy pulsing into the bore to sustain the resonance. What we need is for it to be in the Goldilocks zone ... just right! It is the same issue when you try to blow
a flute and direct your air flow in the wrong place. The flute just doesn't sound.


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PostPosted: Sun Dec 20, 2020 3:38 pm 
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paddler wrote:
What we need is for it to be in the Goldilocks zone ... just right!

Thanks. As a total ignoramus, I would have thought that so much unused air was simply wasted, but now I see that there's far more to it than that. Might a possible, if distant, analogy be that of using the bow in the best way on a fiddle string?

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PostPosted: Sun Dec 20, 2020 5:00 pm 
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Described in the context of flute - which has more variables - here: https://newt.phys.unsw.edu.au/jw/flutea ... tml#airjet

There have been some quite long discussions about it on the flute forum, only the gist of which - and where to look it up - stick in my mind.

@Nano - I think the answer may be here: https://newt.phys.unsw.edu.au/jw/violindex.html


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PostPosted: Mon Dec 21, 2020 8:56 am 
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HaHa. In the age of Covid this illustrates why we whistle players are more likely to shoot the virus out at our friends than our fiddle playing neighbors. Keep safe folks. :)


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