[Shaku] Shakuhachi tuning

I am making Shakuhachi flutes from Black bamboo, dia approx 20mm, of vary=
ing
lengths.
I am using a percentage method to determine the hole position.
I work the blow edge until it gives a good clean sound, then I begin with
the 5th hole, 'Hi' being 42.8 percent the length of the flute. I get a go=
od
note, one octave above Ro. But, after drilling the other four holes, 'Hi'
now differs from 'Ro' by at least one semi-tone, sometimes a lot more.
Flattened on a short 425mm flute, sharpened on a 780mm flute.

I know this is a complex question and am reading regarding 'pressure node=
s',
'flow nodes' and acoustic dynamics of waves, changing hole diameters, but=
 am
interested in anyone's comments on this.

On the other hand, some culms come out 'true'.

Also, is the curve at the lower end of a culm adding back pressure into t=
he
bore ? It seems to say that a kind of 'harmonic feedback' can be created =
by
the 'back pressure' of the bore.

TIA.....Kel =A7

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Received on Mon Jan 9 23:09 PST 2006