HeadBower: Towards Expressive Violin Control for Musicians with Quadriplegia

Accessible Digital Musical Instruments (ADMIs) offer significant potential for musical expression to individuals with quadriplegia, yet achieving fine-grained, expressive real-time control remains a considerable challenge. This paper introduces HeadBower, an experimental ADMI designed to investigate expressive violin control for this user group. HeadBower translates head movements into nuanced violin bowing gestures—horizontal rotation velocity for intensity/sweep, directional changes for note events, and head roll for modulations like vibrato/pitch bend—while also exploring supplementary jaw and mouth sensor inputs for finer articulatory control over parameters such as bow pressure. For note selection, HeadBower implements gaze tracking with two distinct visual paradigms—including a novel circular dynamic layout—both aimed at fluid playability while mitigating the Midas Touch problem. To enhance performer connection, HeadBower experimentally integrates smartphone-delivered haptic feedback. This research details these mapping strategies and interface designs, highlighting their potential to provide multifaceted, expressive violin performance capabilities for individuals with severe motor impairments. All hardware and software components are released under open-source licenses to promote accessibility and further development.