Terry McGee wrote:Geoffrey
So it forces us to consider why the xiao has reasonable-to-good intonation whereas a plain cylindrical "Irish flute" is perfectly ghastly.
Am I right in thinking that xiaos (if that's a legitimate plural of xiao!) have absolutely zero "stopper" cavity. The embouchure is co-located with the node forming the stopper? So there is no "stopper cavity". That would be a major point of difference to our side-blown (allegedly for our protection) flutes?
Secondly, how big are xiao finger holes? Bigger than Irish flute? The bigger the holes, I imagine the less is the flattening effect in the second (and subsequent octaves). And therefore the less is our need to taper bore or head to compensate. (But that statement may need close examination.)
Are there other points of difference you can perceive? Let's get that far and regroup....
I have a few theories (or rather observations) about this. In an earlier post I commented on the surprisingly good intonation on the Indian bansuri, which I credit to a combination of hole size, wall thickness and stopper placement. Thin walls, large holes and (very importantly) a stopper that is moved quite close to the embouchure. When I make a bansuri in D, it varies from the more common cylindrical "Irish" flute in that it has a larger bore for the key (typically in the 21-22mm range) and the stopper is backset just a couple of millimeters from the near edge of the embouchure hole. On a narrower bore flute this seems to strangle the tone, but on the larger bore bansuri it works just fine, and the second octave intonation is impressive.
The xiao is a different animal. A xiao in D has a 17.3mm bore (.68") and small finger holes. The holes are uniformly sized on the outside of the bore, though I undercut most of them to varying degrees. Because it is endblown, there is no backset at all. In fact, because it is a notched flute, the "node" (on bamboo flutes) closes the end of the flute at the mouthpiece except for a small window under the notch. With open-ended xiao, the player's chin does the same, like on a shakuhachi flute. So this closed end is the virtual equivalent of having the stopper positioned half-way through the embouchure hole on a transverse flute! So right off the bat, that is going to help a
lot with the flattening of the second octave. I believe this is the primary reason that the xiao has such good intonation. And I'm speaking specifically of the bei xiao, which is the version from Northern China (long and narrow with a capped end). There is another type from Southern China that is more like a shakuhachi, often made from root end bamboo that has a natural taper toward the foot, but that is another matter.
So effective is this design that with some pretty conservative undercutting the flute will play in excellent tune up into the third octave. It is very similar in some respects to the conical bore flutes we are all familiar with in that to get a nice tuning balance there are a couple of little compromises. The C natural note is very important in Chinese music, so to get it in good tune on the xiao, the maker has to tune the B note a hair sharp and the C# note a bit flat so that the cross-fingered C natural plays on target. But the intonation on a well-made xiao is as good as on any conical bore flute I've played. The xiao also has a lot of extra length in the body with six tone holes (two tuning holes and four vent holes below them). A friend who makes a study of this calls it the "tone hole matrix" and it has an effect on the harmonic character of the flute and the stability of certain notes. The physics behind it is out of my reach, but the Chinese makers figured this out centuries ago and made it part of the design. It is one of the coolest folk flutes ever. You can play ITM tunes on it if you choose
And because it is an 8-hole flute it has much greater range and versatility than a keyless Irish flute.
And because the design is so fully realized, my own modest attempts to "improve" it were hopeless. I tried a variety of experiments, from altering the notch size, to changing the tone hole matrix, altering the wall thickness radically and creating a taper at the head of the flute. In each case it was a backward step. I realized that hundreds of years of development went into this flute with a lot of clever makers experimenting with it, and it was a bit arrogant for me to think I was going to think of something they hadn't already considered. I don't think the flute can be improved, only changed so that it no longer sounds and behaves like a xiao. The tapered head brought no advantage and only strangled the tone.