SoneSkalen

SoneSkalen is a framework for describing perceived loudness in complex sounds by mapping physical sound levels to perceptual scales derived from the sone unit. It is intended as a family of scales rather than a single measure, designed to capture how loudness grows with frequency content, bandwidth, and temporal dynamics. The framework integrates psychoacoustic findings about how humans perceive loudness, distinguishing it from purely physical measures such as sound pressure level or phon-based weightings.

Its core components include the Main Scale (MS), expressed in sones and serving as an overall loudness metric; the Frequency-Stacked Scales (FSS), which provide frequency-band specific values; and the Dynamic Evolution Scale (DES), which tracks rapid changes in loudness over time. A typical workflow begins with analyzing a sound into frequency bands, converting each band’s level to a sone-based value using a psychoacoustic transfer function, applying spectral and temporal masking adjustments, and then aggregating across bands and time to yield a time-resolved SoneSkalen trajectory. Calibration uses reference stimuli near the standard 1 sone baseline.

Originating from collaborative work at the Institute for Psychoacoustic Studies and related centers in the early 2020s, SoneSkalen has seen use in psychoacoustic research, loudness modeling for audio production, and experimental hearing studies. Advocates argue it provides a more perceptually faithful metric than SPL or phon-weighted measures, while critics note unresolved individual differences, context effects, and the lack of formal standardization. As a result, SoneSkalen remains primarily a research tool and prototype implementations in some audio software, with ongoing work aimed at validation, simplification, and potential standardization.