Studies in bowing point friction in bowed strings

Abstract

By using force transducers at the terminations of a violin E string, one may reconstruct the force and velocity at the bowing point that produces those termination forces [R. T. Schumacher and S. Garoff, Institute of Acoustics, Proceedings, Vol. 19: Part 5, 43–48 (1997) (ISMA’97)]. That information, combined with examination of the ‘‘friction track’’ [R. T. Schumacher and S. Garoff, CAS J. 3(2), 9–16 (1996)] allows the possibility of determining the frictional properties of the rosin-mediated bow–string interaction. The reconstruction of the force, f(t), and velocity, v(t), allows determination of the force–velocity relation F(v). That reconstruction is a delicate operation requiring careful measurement of the reflection functions of the transverse waves at the terminations. Use of simulations aids in determining the limitations of the reconstructions. Knowledge of F(v), combined with examination of the friction track, variation of the chemical constituents of the rosin, and chemical preparation of the string surface, as well as measurements of the rosin’s physical properties, such as softening temperature and x-ray structural examination, will eventually establish the physical basis for the alternating adhesion–lubrication properties of the rosin that produce the slip-stick string oscillation.