Accessibility and dimensionalty: enhanced real-time creative independence for digital musicians with quadriplegic cerebral palsy

Inclusive music activities for people with physical disabilities commonly emphasise facilitated processes [1], based both on constrained gestural capabilities, and on the simplicity of the available interfaces. Inclusive music processes employ consumer controllers, computer access tools and/or specialized digital musical instruments (DMIs). The first category reveals a design ethos identified by the authors as artefact multiplication – many sliders, buttons, dials and menu layers; the latter types offer ergonomic accessibility through artefact magnification. We present a prototype DMI that eschews artefact multiplication in pursuit of enhanced real time creative independence. We reconceptualise the universal click-drag interaction model via a single sensor type, which affords both binary and continuous performance control. Accessibility is optimized via a familiar interaction model and through customized ergonomics, but it is the mapping strategy that emphasizes transparency and sophistication in the hierarchical correspondences between the available gesture dimensions and expressive musical cues. Through a participatory and progressive methodology we identify an ostensibly simple targeting gesture rich in dynamic and reliable features: (1) contact location; (2) contact duration; (3) momentary force; (4) continuous force, and; (5) dyad orientation. These features are mapped onto dynamic musical cues, most notably via new mappings for vibrato and arpeggio execution.