The harmonicity of brain dynamics: A neurophenomenological approach to creative biofeedback

Abstract Biological rhythms exhibit harmonic relations that can be operationalised for art–science creation. We introduce a neurophenomenological framework that treats the harmonic architecture of brain–body oscillations (HABBOs) as a compositional medium and guiding signal for real-time feedback. Methodologically, we compute the harmonicity of spectral peaks from electrophysiological time series (e.g., brain, heart), derive adaptive microtonal tunings via timbre–tuning alignment and dissonance-curve analysis, and render evolving tension–resolution trajectories through a sonification method we call harmonic audification. Building on these tools, we prototype creative brain–computer interfaces (cBCIs) that align auditory feedback with a participant’s harmonic landscape, enabling embodied exploration of attention, affect and creativity through closed-loop interaction. To broaden access, we release the Biotuner Engine, a web application that transforms oscillatory data into MIDI tunings and chord progressions alongside the companion open-source toolbox for research pipelines. Our contributions are as follows: (1) formalisation of HABBOs for creative biofeedback; (2) algorithms for extracting and tracking bioharmonic structure and transitional harmony; (3) cBCI design principles coupling neural dynamics to adaptive sound; and (4) accessible software for artists and scientists. We argue that modelling harmony in biosignals offers a rigorous bridge between musical form and neural dynamics, opening transdisciplinary pathways for performance, sonification and empirical study.