Torsional behaviour of cello strings

The behaviour of a bowed string depends, among other things, on the frequen cy, impedance and internal damping of torsional waves on the string. Very l ittle published information is available about these quantities, especially the torsional damping. Measurements of all relevant torsional properties h ave been mode on cello strings of three different constructions. These show that the torsional modes are harmonically spaced to reasonable accuracy, a nd that the Q factors are approximately equal for all modes of a given stri ng. These torsional Q factors are roughly an order of magnitude smaller tha n those of the transverse modes of the same string. The torsional wave spee d varies somewhat with the tension in the string, decreasing with higher te nsion. The damping factors are not significantly influenced by tension. The se results have been expressed in terms of a novel "reflection function" [1 ] suitable for direct incorporation into simulations of the bowing process.