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octaves
http://forums.chiffandfipple.com/viewtopic.php?f=1&t=105691
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Author:  Dan A. [ Tue Dec 05, 2017 8:47 pm ]
Post subject:  Re: octaves

I tried as s1m0n suggested before I began today's practice session, and I did indeed get the note I usually do. I'm still struggling with the high D and the high E, though. I suspect that is due to unintentionally finding that third octave. When I hit those notes correctly (or at least don't get that overly shrill sound), it's almost euphoric...and then I spend umpteen tries to duplicate the result. Kind of like learning how to drive a manual transmission, I guess...

Author:  brewerpaul [ Wed Dec 06, 2017 6:37 am ]
Post subject:  Re: octaves

jpwinstruments wrote:
I often see people saying blow harder to play the second octave, but what I like to tell people is to blow faster. I think it can help you develop good technique by thinking about it that way.

How do you blow faster rather than harder?

Author:  s1m0n [ Wed Dec 06, 2017 7:12 am ]
Post subject:  Re: octaves

By tightening your embouchure so that the Bernoulli effect speeds up the same volume of air, I suppose. Hard to do when you're a n00b and lack the muscle tone.

Author:  Tommy [ Wed Dec 06, 2017 9:38 am ]
Post subject:  Re: octaves

brewerpaul wrote:
jpwinstruments wrote:
I often see people saying blow harder to play the second octave, but what I like to tell people is to blow faster. I think it can help you develop good technique by thinking about it that way.

How do you blow faster rather than harder?


Hmmmmmmm............ :-? Thats a fair question.

Author:  david_h [ Wed Dec 06, 2017 4:33 pm ]
Post subject:  Re: octaves

s1m0n wrote:
By tightening your embouchure so that the Bernoulli effect speeds up the same volume of air, I suppose. Hard to do when you're a n00b and lack the muscle tone.
If the same volume of air is moving faster then it has more momentum than when it was moving more slowly, so you must have supplied extra energy. Which is why asking how you do it without blowing harder is a good question.

I think the point is that it is the faster air stream that results the octave shift and that thinking of that as what you are doing can somehow help more than simply thinking 'blow harder'.

Author:  s1m0n [ Thu Dec 07, 2017 12:33 am ]
Post subject:  Re: octaves

david_h wrote:
If the same volume of air is moving faster then it has more momentum than when it was moving more slowly, so you must have supplied extra energy.


No, the Bernoulli principle says that if you move a fluid through a constricted passage, it has to speed up. That's why you constrict the end of a hose to make the water spray. The energy behind water pressure was applied at the far end of the system, in the water tower, or rather by the pump that fills the water tower, and it's constant.

Similarly with fluting, the pressure in your breath is supplied by your diaphragm, but the speed of the air exiting your mouth can be controlled by your lips. Make the aperture smaller and the same amount of air has to go faster.

Author:  s1m0n [ Thu Dec 07, 2017 12:35 am ]
Post subject:  Re: octaves

In any case, the 'blow faster' nostrum applies to fluting, not whistles. For a whistle it's nonsense.

Author:  david_h [ Thu Dec 07, 2017 3:19 am ]
Post subject:  Re: octaves

s1m0n wrote:
No, the Bernoulli principle says that...
I checked my physics textbook before posting. The derivation of Bernoulli's equation uses the principle of conservation of energy. So in responding to your statement I chose to cut straight to that because it's simpler. Same mass going faster has more energy - where did it come from? (But why do you say the same volume anyway?)

Why do I have to press my thumb harder to make the jet of water from a hose pipe faster? How would things differ if I had my thumb over a hole in the bottom of the water tower tank?

Jet speed is more relevant for whistles than flutes because the length of the jet is fixed on a whistle (by the window height) but a flute player can and usually does change it when changing octave.

Author:  Tunborough [ Thu Dec 07, 2017 7:01 am ]
Post subject:  Re: octaves

s1m0n wrote:
In any case, the 'blow faster' nostrum applies to fluting, not whistles. For a whistle it's nonsense.
Not nonsense, actually. Research by Soizic Terrien, et al., "Regime change thresholds in fute-like instruments: influence of the mouth pressure dynamics", has shown that an experienced recorder player has more control over the breath pressure of octave breaks than a novice or even an artificial blowing machine.

See /viewtopic.php?f=1&t=99890 for some opinions on how it's done.

Author:  david_h [ Thu Dec 07, 2017 8:04 am ]
Post subject:  Re: octaves

If brewerpaul's question "How do you blow faster rather than harder?" can be interpreted as "how do you increase the jet speed without increasing the pressure" then reducing the volume of air moved allows this without violating the principle of conservation of energy. This is possible on a flute because we have control over the orifice from which the jet issues. It is one reason that a flute player with a 'developed' embouchure can make their air last longer, reach the second octave without blowing as hard as a novice, and can play more quietly.

Is it possible on a whistle? With the opening of the windway inside the mouth possibly not*. However, some time back there was a discussion about influencing whistle tone with embouchure techniques and some people described blowing a jet of air into the entrance of the windway from a gap in their lips. It was clearly an advanced technique and the difficulty of knowing what one is doing, as mentioned by Richard above, reduced the credibility of some descriptions for me. However, IIRC one of the those reporting the technique was MTGuru so I am inclined to believe it is real.

* the expert ability described in the article linked by Tunbourough could be something else.

Author:  s1m0n [ Thu Dec 07, 2017 2:39 pm ]
Post subject:  Re: octaves

david_h wrote:
(But why do you say the same volume anyway?)


Because volume is the other variable. If ten litres of air has to pass through a 10 cm² portal in 1 second, it has to go a certain speed. If it has to go through a 5 cm² portal in the same time, it has to move at twice the velocity. If you keep the velocity constant, you can only move five litres of air in the same time.

Author:  david_h [ Thu Dec 07, 2017 3:24 pm ]
Post subject:  Re: octaves

But there is no such constraint. If you progressively close off the end of a hosepipe you get a finer and faster jet - and then you get nothing. The common description of the 'Bernoullu effect' is of a constriction within a pipe not at the end of the pipe where, if its a hosepipe or the window of a whistle, the pressure is atmospheric.

What jpwinstruments said was "I think it can help you develop good technique by thinking about it that way" . By thinking about it that way It's about thinking, not physics. If you want to get the air to go down the windway of a whistle faster all you can do is increase the pressure at your end and so use more air.

Author:  s1m0n [ Thu Dec 07, 2017 3:58 pm ]
Post subject:  Re: octaves

Yes. As I've said, it doesn't apply to whistles.

Author:  david_h [ Thu Dec 07, 2017 4:15 pm ]
Post subject:  Re: octaves

Constant volume, as a general case, does not apply to flutes. And Bernoulli's equation is on the same page or two of the book but is not the best way of looking at an orifice with a pressure difference on either side.

Author:  Tunborough [ Fri Dec 08, 2017 7:01 am ]
Post subject:  Re: octaves

david_h wrote:
If you want to get the air to go down the windway of a whistle faster all you can do is increase the pressure at your end and so use more air.
It isn't clear that's the only variable we control. The evidence suggests that there other factors at play. And if there are, we can be sure our bodies will figure out how to control them, even if we aren't conscious of what we're doing.

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