1 CoCo Lab, Department of Psychology, Université de Montréal, Montreal, QC, Canada. antoine.bellemare9@gmail.com.
2 Music department, Concordia University, Montreal, QC, Canada. antoine.bellemare9@gmail.com.
3 CoCo Lab, Department of Psychology, Université de Montréal, Montreal, QC, Canada.
4 Mila (Quebec AI research Institute), Montreal, QC, Canada.
5 UNIQUE Center (Quebec Neuro-AI research Center), Montreal, QC, Canada.

Background: The Biotuner Toolbox is an open-source Python toolbox for biosignals that integrates concepts from neuroscience, music theory, and signal processing. It introduces a harmonic perspective on physiological oscillations by applying musical constructs such as consonance, rhythm, and scale construction.

Methods: The core biotuner_object processes neural, cardiac, and auditory time series, providing a unified interface for extracting spectral peaks, computing harmonicity metrics, and supporting downstream analyses. Companion modules extend harmonic analyses across temporal (time-resolved harmonicity), spatial (harmonic connectivity), and spectral (harmonic spectrum) dimensions.

Results: Biotuner identifies harmonic structure across different biosignals, revealing significant variations in harmonicity between physiological states. Specifically, the toolbox extracts spectral peaks from complex signals using multiple algorithms, ensuring robust peak detection under varying signal-to-noise ratios. Moreover, we show how harmonicity metrics change across distinct sleep stages and capture variations in the slopes of the aperiodic (1/f) component of the power spectrum.

Conclusion: Biotuner provides an extensible framework that unifies music-theoretic constructs with biosignal processing, enabling hypothesis-driven analyses for researchers and, in parallel, creative exploration of complex natural patterns for artists.