ShakuhachiFacts - An Interesting Bore

How many times have you looked downinside a shakuhachi and wondered: "Just where does that soundcome from?" Why does every piece of bamboo have a uniquesound and for that matter, why does the same flute played by twodifferent people sound different?" The movement of air insidea shakuhachi is of quantum-boggling complexity, but there is abeauty and order to the natural universe that is magical.

So let's talk about magic: air moleculesare constantly banging around and in a small chamber such as ashakuhachi bore they bounce off the walls creating a slightlyhigher pressure. When you blow into the flute the air bunchesup and springs back-- it's very elastic stuff. As you blow overa sharp edge, the air bunches then springs back and helps to redirectthe blowing slightly "out" of the flute, then back "in"the flute in a fast sequence that reinforces itself and sets upthe vibrations we hear as sound.

The point where the air bunches togethermost (before springing back) is approximately half-way down avibrating tube and is the acoustic equivalent of the center pointof a vibrating string, the point which has the greatest movement.On shakuhachi, I call these "pressure points", althoughthey are more accurately called points of the most intensificationand most rarefication (when the air springs back in both directionsthe pressure is lowered).

As the most dynamically active pointor place in the bore for any given tube length, this is the mostimportant spot. If it is a little too big or small (to the orderof .02mm!) the vibration may not resonate easily. However, likeproblems encountered at a large family gathering, everything isrelative, bores are only small or large in relation to their surroundings,and other usually unimportant factors can affect the balance ofthe gathering.

Everything about the bore, which includesthe configuration of the player's mouth, the mouth piece, andthe finger holes, affects the sound. In a very real sense, whena shakuhachi maker is shaping the bore, he is shaping the sound.Add to this the personal preference of such important tone-characterizingfactors as vibrato, attack, and decay and it is no wonder thatno two shakuhachi players sound alike!

Trying to make sense of all this islike driving around at night in Tokyo without lights: there area few road signs, but without more light we are still lost. Forthose who would like their confusion clarified, I recommend toyou the books listed at the end of this article, but I will givea bit more direction on how the chart works(Click here to see the chart).

Let us say that "chi otsu"(or the low octave with three holes open from the bottom) doesn'tplay well compared to the other notes around it. It may be thatthe pressure point is too small or too big; that is the firstplace to look. Try putting a piece of wet folded newspaper atthe point to make the bore smaller. If it works, fine; if it getsradically worse, chances are that point is too small (relativelyspeaking of course).

Now it may be that it is in fact the"chi kan" point(s) (for the higher octave there aretwo pressure points) that is too small or too big and negativelyaffecting the fundamental "chi otsu." All the notesare affected by the whole tube, but such close relatives as theoctave must be taken into account and influence such importantthings as pitch and tone color as well as the basic balance betweenlow and high notes. In other words, depending on how the wholeflute plays, it is sometimes better to make other areas smaller(or larger) so that the point that needs help will be relativelylarger (or smaller). To complicate matters even more, every pointyou change may alter totally "unrelated" notes. Lookat the chart vertically to see the interrelatedness: for examplethe "ro otsu" and the "chi kan" point (oneof them anyway) are very close. Working out this and other puzzlesto make an instrument which plays with some "balance"(definition: all notes respond well, high/low, loud/soft) is anamazing process.

One way to hear the way the chart worksis by opening up the middle joining section 4 or 5 millimeters.This effectively makes the bore larger at that point. See whathappens to "ro otsu" (the lowest note) and "rokan." Check on "chi otsu" and "chi kan."Does it affect other notes as well? Push the flute together andtake apart repeatedly to confirm any changes.

It is complex, but it isn't unapproachable:the air inside a shakuhachi obeys the laws of physics in waysyou can hear for yourself. Check it out ..... the bore is interesting!

Backus, John
1977 The Acoustical Foundations of Music, W.W. Norton & Company,Inc., New York

Benade, Arthur H.
1976 Fundamentals of Musical Acoustics, Oxford University Press,New York

Nederveen, Cornelis J.
1969 Acoustical Aspects of Woodwind Instruments, Frits Knuf, Amsterdam

One word of caution: obviously any permanentmodifications done to a shakuhachi should be done very carefully.... a wild bore is not easy to play with!