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Sculpting musical sound. David N Lee Perception-Movement-Action Research Centre University of Edinburgh Talk given at Shaping Music in Performance Workshop King’s College, London 10-11 March 2010. Summary of talk. A theory of action control and applications to understanding moving
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Sculpting musical sound David N Lee Perception-Movement-Action Research Centre University of Edinburgh Talk given at Shaping Music in Performance Workshop King’s College, London 10-11 March 2010
Summary of talk A theory of action control and applications to understanding moving and making music
Action-gaps • Acting requires controlling action-gaps between current state and goal state • Controlling action-gaps requires prospective sensory and intrinsic information
Multiple action gaps • Acting generally requires controlling several action-gaps contemporaneously
τ • The principal informational variable for controlling action-gaps is τ • τ is the time-to-closure (or the time-from-closure) of an action-gap at the current rate of closing (or opening) • τ of action-gap, X, equals
Properties of τ • Action-time variable • Prospective informational variable • Universal variable • Directly perceptible
τ-coupling • Foundation for controlling action gaps • Means the ratio of the τ s of two gaps is constant
Intrinsic guiding gaps • Should be simple and sufficient • Should be rooted in ecological physics
(a) TauG guidance TauD guidance x Normalized time Normalized time
TauG-guidance parameters K = ‘oomph’ A = amplitude T = duration
m-g m-g
Va---ne pitch (Hz) 1 s TauG-guidance of pitch-glide singing
Future directions We have shown how, at the few hundred millisecond level, the shape of a musical sound (pitch and intensity glides) mirrors the shape of the movement that produces it. Both follow the same tauG mathematical formula. We are now moving in two new directions: to the sub-millisecond level to explore how sound waves are sculpted to generate the timbre or quality of sound, and to the supra-second level to explore how the shapes of musical phrases are sculpted. Preliminary results suggest that tauG also features at these two levels.
References Schogler, B., Pepping, G-J. & Lee, D. N. (2008). TauG-guidance of transients in expressive musical performance. Experimental Brain Research, 198, 361-372. Lee, D. N., & Schogler, B. (2009). Tau in musical expression. In S. Malloch & C. Trevarthen (Eds.), Communicative Musicality: Exploring the basis of human companionship. Oxford: Oxford U. P. Lee, D. N. (2009). General Tau Theory: evolution to date. Special Issue: Landmarks in Perception. Perception, 38, 837-858.