Increasing harmonic richness in Western Classical music

"we find that [harmonic] vocabulary richness undergoes a clear increasing trend across the history of music, as expected from qualitative musical wisdom. "https://t.co/etIEZJDCMo pic.twitter.com/XxiUMeo7Ad

— Alberto Acerbi (@acerbialberto) August 19, 2021

The abstract for the linked article:

Music is a fundamental human construct, and harmony provides the building blocks of musical language. Using the Kunstderfuge corpus of classical music, we analyze the historical evolution of the richness of harmonic vocabulary of 76 classical composers, covering almost 6 centuries. Such corpus comprises about 9500 pieces, resulting in more than 5 million tokens of music codewords. The fulfilment of Heaps’ law for the relation between the size of the harmonic vocabulary of a composer (in codeword types) and the total length of his works (in codeword tokens), with an exponent around 0.35, allows us to define a relative measure of vocabulary richness that has a transparent interpretation. When coupled with the considered corpus, this measure allows us to quantify harmony richness across centuries, unveiling a clear increasing linear trend. In this way, we are able to rank the composers in terms of richness of vocabulary, in the same way as for other related metrics, such as entropy. We find that the latter is particularly highly correlated with our measure of richness. Our approach is not specific for music and can be applied to other systems built by tokens of different types, as for instance natural language.

See my Stages in the Evolution of Music, Journal of Social and Evolutionary Systems, 16(3): 273-296, 1993, https://www.academia.edu/8583092/Stages_in_the_Evolution_of_Music.