Modelling dynamics of key induction in harmony progressions

This paper presents a statistical model of key induction from given short harmony progressions and its application in modelling dynamics of on-line key induction in harmonic progressions with a sliding window approach. Using a database of Bach’s chorales, the model induces keys and key profiles for given harmonic contexts and accounts for related music theoretical concepts of harmonic ambiguity and revision. Some common results from music analytical practice can be accounted for with the model. The sliding window key induction gives evidence of cases in which key is established or modulation is recognised even though neither dominant nor leading tone was involved. This may give rise to a more flexible, probabilistic interpretation of key which would encompass ambiguity and under-determination. In addition, a novel method of harmonically adequate segmentation is presented. Keywords— key induction, harmony, music cognition.