MODELLING AND EXPERIMENTS ON STRING/BODY COUPLING AND THE EFFECTIVENESS OF A CELLO WOLF-KILLING DEVICE
Vincent Debut, Octávio Inácio, Thibaut Dumas, José V. Antunes · 2010
A common annoying phenomenon which arises with most cellos and violas is the so-called note. This is a warbling sound stemming from a severe interaction between the string and the body motions, coupled through the instrument bridge. Instrument builders have found that adding a small auxiliary mass on the so-called side of the string often inhibits the wolf phenomenon. However, the tuning of such wolf-eliminators is often laborious, erratic, if not ineffective, because the physical role of such devices is still poorly understood. Following our previous work on this problem, we address the dynamical behavior of the string/body/wolf-eliminator coupled system, which is studied here in a more systematic manner, both theoretically and through experiments performed on a XIXth century cello. We briefly recall our fully coupled model for this problem, and then perform extensive hand-bow experiments, as well as illustrative computations, which show the effectiveness of this wolf-eliminator as a function of the device mass and location along the dead side of the string. This experimental and numerical work contributes to clarify the functioning of this anti-wolf device and provides guidelines for an effective use.