The University of Adelaide
Abstract :
The development of a high resolution finite element model of
the Japanese koto has been previously reported. The koto is a
plucked zither made of paulownia wood and 1.83m in length. Its
13 strings are made of polyester fibre and supported by 13
moveable bridges approximately 6cm high. A functional
representation of each string was included in the high resolution
model by using a wave form that entered the koto sounding
body at a signal point where the bridge would be located for
the standard (hirajōshi) tuning. Correlation between spectra
generated in the model and spectra of an actual instrument as
played provided initial observations of string behavior. This study
aims to improve the fidelity of the spectral response by directly
coupling the string to the resonating body. A beam model and
a truss model with the dimensions of a professional string that is
pre-tensioned to yield a close approximation of strings on an
actual instrument are studied. The nature of the boundary
conditions at either end of the string is discussed. Simulation
results from the two models as compared to notes played on
the koto used as the basis of the finite element modeling are
reported.