Q2: Which aspect in the construction of the shakuhachi is most critical to the production of tonal quality?
A: There appears to be no clear-cut consensus on the issue of which factor contributes most to producing the best sounding instruments. In regard to the shakuhachi, opinion tends to be divided along two lines. The traditionalists often point to the bamboo—where it is grown, how hard or dense it is—and other materials are used in making the instrument. Those who have studied the acoustical physics of the shakuhachi and other wind instruments, strongly emphasize the shape of the bore and structural aspects of the flute as the major determinants of sound production. Some traditional teachers claim that a shakuhachi used by an exceptionally good player will, over the years, be transformed into a better instrument. Most authorities on the science of sound assert, to the contrary, that the material used in making a woodwind is virtually insignificant when weighed against structural design and resonating air column defined by the bore profile of an instrument.
This debate is one that has ensued in the flute world for over a century. Arguments pro and con often shed more heat than light. Nonetheless, I have noticed that makers of quality shakuhachi in Japan and woodwinds of all types throughout the world, spend an inordinate amount of time and detail in careful fabrication of the bore to a precise set of specifications. Traditionalists and scientists alike concur in this regard. I have also observed that in Japan, this "unseen" aspect of the shakuhachi is frequently overshadowed by the appearance of the bamboo and/or the name of a famous teacher or maker stamped on the flute. Objective evaluation of tone and market value based on aesthetic or historical factors are sometimes intricately intertwined with shakuhachi.
A thorough discussion of this issue is explored in my book, STALKING THE WILD BORE: A Search into Shakuhachi Darkness.