Abstract: The computational analysis of music has traditionally seen a sharp divide between the "audio approach" relying on signal processing and the "symbolic approach" based on scores. Likewise, there has also been an unfortunate gap between any such computational endeavour and more traditional approaches as used in historical musicology. In this paper, we take a step towards ameliorating this situation through the application of a computational method for visualizing local key characteristics in audio recordings. We exploit these visualizations of diatonic scale content by discussing their musicological implications, being aware of methodological limitations as for the case of minor keys. As a proof of concept, we use this method for investigating differences between the traditional sonata-form model and selected Beethoven piano sonatas in the context of sonata theory from the end of the 18th century. We consider this scenario as an example for a rewarding dialogue between computer science and historical musicology.