Some shakuhachi acoustics

This site gives some preliminary information about our measurements of the acoustics of the shakuhachi, and of the shakuhachi player.

We measure a quantity called the acoustic impedance spectrum, which may be considered as the response of the instrument to all frequencies. This quantity is measured on the instrument itself, without a player. For an explanation of this quantity, see What is acoustic impedance?. For a preliminary introduction to the acoustics of the flute family, see Introduction to flute acoustics.

The acoustic impedance spectrum of the shakuhachi, measured at the input, for the standard fingerings for the notes ro and tsu. The impedance is plotted in dB, i.e. 20 log (Z/Pa.s/m^3). The instrument measured was a Bei Shu model (Nagano Ken, Japan).

Abstract for the 140th meeting of the Acoustical Society of America, 6 December 2000

Some acoustics of the shakuhachi--and of the shakuhachi player's face. Joe Wolfe and John Smith

The shakuhachi is an end-blown Japanese flute. Like other flutes, it is open at the place of excitation, so it operates at minima of the acoustic impedance. The jet interacts with both the bore impedance and the radiation impedance, which is baffled by the player's face. Large changes in the relative geometry of the instrument and the face contribute to the flexibility in pitch and timbre that are important elements of the traditional playing style, and which gives the instrument much of the expressiveness for which it is renowned.

We report measurements of the impedance spectra (Z(f)) of the bore, and of the baffled radiation load imposed on the jet. Z(f) of the instrument differs from that of the Western flute family because the shakuhachi has neither the narrow chimney of the Western flute, nor the short resonator upstream of the jet. These influence the overal form of Z(f) for the instrument. Other features of Z(f) are explained by the tone hole position and geometry. The Z(f) of the radiation field varies for different playing positions, which has important effects on the tuning of the minima and on the spectral response.

A lay language version of this conference paper is available.

Some related publications. The first of these papers compares the shakuhachi with Western flutes. The second is a technical study of Western flutes from the classical and modern periods. Both are .pdf files.

There is a more detailed discussion of flute acoustics in the main flute site, and in some of our research papers on this topic. We also recommend The Physics of Musical Instruments by N.H. Fletcher and T.D. Rossing (New York: Springer-Verlag, 1998). For the non-scientific reader, there is also an introduction to How do woodwind instruments work..

Our collaborators are the shakuhachi maker Tom Deaver, of Nagano Ken, Japan, and the shakuhachi player Riley Lee, of Springwood, Australia. We thank them for their assistance.

The International Shakuhachi Society has more information, and links to other shakuhachi sites.


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