Some Aspects Of The Biomechanics Of Skilled Musical Performance

This chapter addresses a fundamental aspect of musical performance in string players: how the physical "geography" of the instrument and bow, and the anthropometric dimensions of the player interact to produce the stereotypic motor behavior.Several factors determine movement, but, unlike most biomechanical tasks, the determining outcome here is acoustic. Both upper extremities are involved in the performance but in very different ways.The left arm governs the contact position of the fingers on the string, and hence the pitch of a note. The spatial relations of the instrument to the body, the contact point of the finger on the string, the length of the fingerboard, and the dimensions of the arm determine a unique posture, and thus the muscle activation patterns, for the left arm for each individual player. The left arm has quite different postures in relation to the body and the instrument for cello players in comparison to violinists.The bowing (right) arm draws the bow across the string. Its travel velocity is the principal determinant of loudness, but its distance from the bridge, the contact position along the bow length, bow pressure, and its angle of attack on the string leave a noticeable effect on the tone, or timbre. Bowing movements are essentially determined by the flexion and extension of the elbow, with subtle motions of the shoulder and wrist to keep the bow moving in a straight line perpendicular to the string. Given a fixed spatial relation between the body of the performer and the instrument, the posture of the arm for a given bow/string contact point is uniquely determined.In addition, the force of gravity plays a role in the control of movement. We show, however, that it affects cellists and violinists in very different ways. Left arm movements of cellists are more affected by gravity than those of violinists; whereas gravity affects the right arm more in violinists.In this chapter we focus on a series of specialized topics: 1) control of the left arm during shifting movements; 2) fine control of the left arm during corrections of intonation errors; 3) coordination between the upper arm and forearm; and 4) coordination between the left and right arms.