Tuning of the Violin–Performer Interface: An Experimental Study about the Effects of Shoulder Rest Variations on Playing Kinematics

Abstract

Playing a musical instrument is a constrained motor activity; the instrument has a fixed geometry and playing technique that the performer must accommodate. Although the performer progressively adapts to the instrument during years of education, few options are available for adapting the instrument to the performer. The present work is intended to quantitatively describe the effects of using different setups of the violin shoulder rest during performance. Three conditions were considered, the maximum and minimum heights allowed by the shoulder rest and the absence of the shoulder rest. The setups allowed a height variation of <40 mm. Fifteen skilled violin players performed a three-octave scale in G with the three rest setups. An optoelectronic motion capture system measured the positions of passive markers placed on the player's body and on the violin and bow, in order to compute, by means of mathematical models, the kinematics of the body, violin, and bow. The increase in rest height was significantly related to a reduction in head rotation (–7.0°), left shoulder rotation (–8.5°), and left acromion elevation (–17.2 mm) and to an increase in left shoulder flexion (+8.2°) and left forearm pronation (+8.8°). In general, the results demonstrate that a skilled player is able to adapt to any shoulder rest setup and can maintain the quality of sound, and that the adaptations are primarily those of the anatomical systems involved in holding the violin and not in holding the bow. Moreover, adjustment of the shoulder rest setup appears to be the individual's search for a tradeoff position, which possibly may be alleviated by adopting objective assessment and innovative shoulder rests.