Real-time finite-difference string-bow interaction floating point gate array (FPGA) model coupled to a violin body
Florian Pfeifle, Rolf Bader · The Journal of the Acoustical Society of America · 2011
A string/bow interaction model as proposed by Bader, R.: Whole geometry Finite-Difference modelling of the violin. In: Proceedings of the Forum Acusticum 2005, 629-634, 2005 and a 3D violin geometry with top plate, back plate, and enclosed air was implemented in real-time using an FPGA hardware implementation. The bow/string interaction uses conditions for gluing and tear-off the string to/from the bow, where gluing happens with relative string/bow velocity below a threshold and tear-off with either the string curvature or the string tension at the bow point too high modelling the cases appearing with normal Helmholtz motion or the occurrence of subharmonics, respectively. The model can be played changing bow pressure and velocity, bow point on the string, and string length. The resulting sounds are highly realistic showing gradual timbre changes from normal Helmholtz motion, double slit motion, weakening of the fundamental, or noise with very low pressures. It appears that these interaction conditions can realistically be used to model the bow/string interaction.