From Control to Co-Agency: Reframing Instrumentality through Sonic Traces in Augmented Musical Practice

Contemporary practices with augmented and digitally mediated musical instruments increasingly question familiar ideas of control, mastery, and instrumental agency. In many such practices, agency is distributed across bodies, technical configurations, spaces, and temporal processes, reorienting instrumental design toward shared agency rather than a primary focus on parameter extension or mapping within a constrained digital domain. From this perspective, musical instruments can be understood less as interfaces to be controlled and more as entwined systems, relational ecologies shaped through listening, bodily awareness, and adaptive (inter-)action.

Grounded in artistic practice, this paper explores how subtle, non-dominant sonic phenomena can function as meaningful resources for interaction with an augmented acoustic instrument. Focusing on a solo bandoneon augmented through live electronics and machine learning, the work articulates the three interrelated concepts of peripheral sounds, gestural remains, and residual resonances that become perceptible through practice, amplification, and learning. Sounds arising from the instrument's materials, friction with the body and lingering resonances are approached not as side effects, but as sonic traces that orient listening and action.

Across the design and composition of a live-electronic ecosystem, a concert performance, and a performative sound installation, these subtle sounds operate as cues for action, shaping movement, timing, and decision-making for both performer and technical system. Attending to such phenomena leads to new gestural strategies, alternative modes of augmentation, and shifts in how listening is organised within performance situations. By reconsidering what counts as signal in augmented instruments that use machine-learning, this work contributes to NIME discussions on affordances, agency, and relational instrument design, foregrounding co-agency grounded in responsiveness and emergent behaviour.