A novel, high-fidelity, shape-sensing technology, BendShape [1], is investigated as an expressive music controller for sound effects, direct sound manipulation, and voice synthesis. Various approaches are considered for developing mapping strategies that create transparent metaphors to facilitate expression for both the performer and the audience. We explore strategies in the input, intermediate, and output mapping layers using a two-step approach guided by Perry's Principles [2]. First, we use trial-anderror to establish simple mappings between single input parameter control and effects to identify promising directions for further study. Then, we compose a specific piece that supports different uses of the BendShape mappings in a performance context: this allows us to study a performer trying different types of expressive techniques, enabling us to analyse the role each mapping has in facilitating musical expression. We also investigate the effects these mapping strategies have on performer bandwidth. Our main finding is that the high fidelity of the novel BendShape sensor facilitates creating interpretable input representations to control sound representations, and thereby match interpretations that provide better expressive mappings, such as with vocal shape to vocal sound and bumpiness control; however, direct mappings of individual, independent sensor mappings to effects does not provide obvious advantages over simpler controls. Furthermore, while the BendShape sensor enables rich explorations for sound, the ability to find expressive interpretable shape-to-sound representations while respecting the performer's bandwidth limitations (caused by having many coupled input degrees of freedom) remains a challenge and an opportunity.
