Is this a Myth? Tremolo & volume change at same pitch on recorder. On Yamaha translucent descant.
Channel: robertinventor
Date: 31/01/2013

Two Tunes played on recorder using tremolo, also volume swells at a fixed pitch like a flute,  (sheet music as kindle book, pdf or abc notation here http://www.amazon.com/gp/product/B016R28IDU )

This is supposed to be impossible to do. I demo on the Yamaha translucent descant here. Also show that you can stop the note in such a way that it goes up in pitch slightly, stays at a steady pitch or goes down in pitch as the note fades away. 

All of this is generally thought to be impossible on recorder. I show how you can achieve it if you want to experiment yourself. Unfortunately the pitch change you initially is likely to be between 5 and 10 cents, or between a fortieth of a tone and a twentieth of a tone. Later you might get a tenth of a tone pitch difference, still quite small by most musical standards as it corresponds to only a subtle pitch vibrato.

Also suggest ways that it could be studied in a physics lab, especially if you can find a way to show up the turubulence within the recorder. The translucent Yamaha recorder I use in this recording might be of especial interest here to - first confirm that it can be reproduced in lab conditions (hopefully), and then find out why it happens.

SOME POSSIBLE HYPOTHESES TO EXPLORE

A physicist might well come up with many ideas to explore to explain why it happens. Here are a few to get started:

My best guess so far is that it might be an effect of introducing turbulence into the air stream which might cause small millimeter sizedl vortices to form in the airway. 

I suggest that, because vortices in air are fairly stable and could easily survive passage through the airway. Also it fits experience well, because you raise the pitch by doing various things to make the air rougher.

Assuming that's the case, then the question is, how does the turbulence change the pitch of the note? I've just had an interesting discussion on the Xenharmonic Alliance facebook page about this with Billy Stiltner, and we came up with several ideas to explore:

* It might reduce the volume of the note when it hits the edge; perhaps the turbulent air hits the edge in an uneven way. This could reduce the volume of the note at a given breath pressure and pitch. So the pitch still depends on breath pressure, but the volume is less, so you can increase the pitch at a steady volume by increasing the breath pressure.

* The temperature of the air or its humidity might change, and so change the speed of sound within the tube, and so the frequency (this is similar to the effect all wind players are aware of, that the pitch goes up in warmer conditions and down in colder conditions).

The idea here is that air from the breath is much warmer and more humid than the air outside the tube, so if there was some way for more warmth and humidity to escape from the mouthpiece in the turbulent situation that might then explain it.

* Another suggestion that might explain the effect is that the turbulence might cause a slight vacuum (like air rushing over the wing of an aeroplane) and reduce the density of air within the tube and so increase the speed of the sound.

* It might be that the turbulence simply causes fluctuations in density within the tube and so causes the speed of sound to vary within the tube so that it isn't constant, similar effect perhaps to slightly changing the shape of the tube in places.

* It might dampen the sound, and so reduce the volume, within the tube

* The turbulence might change the effective width or length of the tube in some way - e.g. if the turbulence "sticks" to the inner surface of the tube.

It might be a combination of several of these effects.

WHY DOES THE PITCH OF THE RECORDER CHANGE WITH AIR PRESSURE ANYWAY

Does anyone know the answer to this? What is it that actually changes the pitch when you increase the air pressure when you play the recorder? Is it density, speed of the air, or what is it? How exactly does this change the pitch of the note played? This might be useful to know first.

THE OTHER EFFECTS

Also really interested to know how and why the tremolo is possible, and how you can change the direction the pitch changes when you stop the note. However as I don't know how I do it, not sure how you would investigate it.

ANY PHYSICISTS LIKE TO LOOK AT THIS?  OR MYTH BUSTERS :)

If any physicists want to take a look at this I would be fascinated to hear what you find out. 

Also wondered if it might be a suitable "myth" for the MythBusters to look at :).

The "myth" to investigate would be that you can change the pitch of a note on the recorder without changing its volume, and change the volume of a note on the recorder, without changing its pitch, all just by changes in the breath as it enters the mouthpiece, with the fingering, and position of the recorder unchanged.

THE TUNES PLAYED

The tunes played in this recording are two tunes I composed in a place which is called the Happy Valley on some maps, in Oxford, in 2006