Intersections in Actuated String Instrument Design, Performance, and Just Tuning Practices

This dissertation examines the intersections between actuated string instrument design and the deployment of just tuning structures in composition and performance practice. Accompanying the written document, we present an original composition, Artemisia, as a tangible demonstration of these integrated practices. We begin by establishing a contextual definition for actuated instrumentation specific to those instruments, devices, and algorithms which employ a secondary or indirect method of inducing acoustic response from one or more strings. This trait distinguishes actuated devices from most other instrumentation, which generally employ or simulate some form of direct activation—usually applied by the performer’s hands, digits, feet, breath, or other faculties. While physical properties may aid in transmitting acoustic vibrations, all instruments and devices discussed within the essay deploy some form of electronic mediation to achieve actuation. Methods for actuation include electronic transducers, sympathetic resonance, or impulses applied to a physical medium or model. To further delineate these methods, we divide electronically-mediated actuation into two sub-categories: electro-magnetic and electro-mechanical.

Chapter two provides a survey of ferromagnetic, Lorentz-Force, and tactile transduction techniques most applicable to actuated string instruments. Here, we discuss how pioneering research by Andrew McPherson, Per Bloland, Nicolas Collins, and others informed the design and construction of the author’s own actuated string instruments: Rosebud I and Rosebud (‘Louise’) II. The following chapter introduces foundational principles in just intonation, focusing primarily upon Otonality, Utonality, Commas, Tonal Flux, Epimoric ratios and other practices relevant to composing and performing with actuated strings. With these principles in mind, we proceed to explicate the compositional structure of Artemisia.

In addition to defining the methods for actuation and tuning, we analyze emergent performance practices associated with actuated instrumentation. Preceding our research, Dan Overholt, Edgar Berdahl, and Robert Hamilton describe three categories of actuated instrument performance practice: “computer-mediated” electronic signals, “self-sustaining oscillation,” and “third-party” audio streams. While all three categories reference the source for actuation, we propose a fourth category: disruptive preparation. This additional category extends Overholt, Berdahl, and Hamilton’s source-based definition to include an exploration of performative interplay, acoustic artifacts, and other nonlinearities produced by interactions between actuated strings and foreign objects, external processing, or other interventions. In the final chapter, we focus upon historical precedents for these modes of performance, as well as those demonstrated in the composition and recording of Artemisia.