Why a Double-Tapered Bore?
If you are serious about getting a decent wooden shakuhachi, do not be fooled by cheaper wooden models that have a straight cylindrical bore. These may sound good in the first octave (Otsu), but as one progresses through the notes of the second and third octave (Kan and Dai-kan) they typically get progressively flatter the higher you go. There are ways to make a straight cylindrical bore play at a higher level with what is called a choke, but to my experience they are not rich in tone color or depth and are not pleasing in sound when used for traditional Japanese music. Nearly all commercially made wooden Japanese student flutes have tapered bores and perform at least at a moderate level. Many teachers do not prefer these though as their bores tend to be on the narrow side. This can help one to get started, as flutes are generally easier to play that have a smaller bore. As a student's embouchure progresses and gets stronger, however, one can outgrow a flute because it cannot take the greater amount of air that the advancing student can put through it.
Advancing students who have initially chosen the narrow bore path will eventually benefit by migrating to a medium to large bore flute. The shakuhachi that we make at Shin-Sei are medium bore. They can take a lot of air, and have a sweet sound while still being a relatively easy shakuhachi to play. Shin-Sei shakuhachi make a great beginner's choice as well as are not usually outgrown--negating the usual selling and searching for another shakuhachi when the smaller bore is no longer sufficient. Shin-Sei Shakuhachi will provide years of depth and discovery and further serve as a reliable backup for those who choose for it not to be their "end flute" and eventually go with traditional bamboo.
Be sure to ask plenty of questions of your flute maker. If they will not let you return a flute within a reasonable amount of time as is akin to beginning to know a shakuhachi (2 to 3 weeks) I recommend steering clear of them. To my knowledge there are only 3 individual non-corporate artisans of wooden shakuhachi worldwide offering double tapered bores. Some makers are not and are priced right along with those who are. More yet are not and though cheaper initially are generally disappointing in their performance.
Good luck. We look forward to serving you should you choose us.