Everything about a shakuhachi effects the sound and feeling of it. From the volume or size of the bore, to the size of the finger-holes, and the edge (utaguchi). Mere millimeters of change can have noticeable or even profound effects.
If a maker crafts a nobé or “whole” jinashi shakuhachi and leaves the inside mostly natural, then nature determines more of the sound and feel. By contrast, a jiari maker fully shapes the inside using paste and adjust the length via a center joint. So they’re shaping most of the sound and feeling.
However, what often matters most is how much air or effort a shakuhachi takes and that matching up with how much air or effort a player likes to use or is capable of. This could be described as the feel of a shakuhachi. Of course, experienced players sometimes play a variety of instruments across a spectrum.
What determines this air-capacity is mostly the size of the bore or inner volume of a shakuhachi (a ratio of length to width). More volume, or simply put “wider” shakuahchi, will accept more air and will also therefore take more effort.
The following is me answering an email from a student and friend about the sound and feeling of shakuhachi.
“Do all shakuhachi have the same potential? Is it all based on the player and not the shakuhachi, in the end?”
All well made shakuhachi have a lot of potential but it depends on the player to bring it out. When comparing well balanced shakuhachi what sticks out to me the most is how much air they take or effort. More narrow bore shakuhachi require less effort for a loud sound while wider bore shakuhachi take more effort to achieve the same volume but are often quieter and darker.
Wider bore shakuhachi can often take blasts of air and one gets the sense they can play a bit more wildly and unrestrained. Narrow bore shakuhachi can also take blasts of air but generally one has to be a bit more careful so as to not overwhelm them which results in high-pitched “squeaking” or shrill octave jumps.
Both are good for different situations, approaches, or levels of ability. I like to play with a lot of power as well as gently, so in other words dynamically. Since most shakuhachi can be played gently with favorable results, I tend to prefer wider bored shakuhachi because I don’t have to hold anything back. It can feel nice to really put in near maximum effort, even if you could get a louder sound for less effort on a more narrow bored shakuhachi. A beginner would find a narrow shakuhachi easier and thus more favorable in most cases.
“Is it just a matter of finding or learning how to play each one [instrument] individually?”
Essentially yes, though well made balanced shakuhachi of any variety should respond to the same methods or techniques from the player to produce certain desirable sounds. Mostly full ringing sounds when pushed into more harmonics or overtones. If a shakuhachi can’t be pushed into these overtones on key notes than physically these shakuhachi are out of balance with themselves. Sometimes though this imbalance is desirable or embraced.
With old jinashi, or jinashi without any bore tuning, one often experiences unbalance on the fundamental note or RO. Often Otsu and Kan will be out of balance with one outshining the other in terms of range or stability when pushed. Almost all shakuhachi benefit from being balanced with careful work in the bore via subtractions and/or additions.