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 balanced shakuhachi have a lot of potential but it depends on the player to bring it out. There are of course shakuhachi which have inherent limits or imbalances which no amount of technique from the player can change. When comparing well balanced shakuhachi, what sticks out to me the most is how much air they take or effort (air-capacity). For example, 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.
Wider-bore shakuhachi can often take blasts of air and one gets the sense they can play a bit more wildly and unrestrained on them. 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. Conversely, one could also describe wider-bore shakuhachi as taking more effort and narrow-bore shakuhachi as being easier.
Both wide and narrow are good for different situations, approaches, or levels of ability. For example, I like to be able to play with both power and gently, so in other words dynamically. Since most shakuhachi can be played gently with favorable results I tend to prefer wider-bore shakuhachi because I don’t have to hold anything back. It can feel nice to really put in near maximum effort on a wide-bore, even if you could get a louder sound with less effort on a more narrow-bore shakuhachi. Most all beginners find 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, the “full ringing sounds” when notes are 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 imbalances are desirable or embraced for a particular aesthetic on very raw jinashi shakuhachi without much or any tuning in the bore. On such shakuhachi one often experiences imbalances on the fundamental note or RO.