Pitch class histograms

Behold pitch class histograms for my post-2018 music HERE.

I undertook to analyze the pitch class content of my compositions, and in doing so, to clarify which of them are the most *atonal*, in the sense of using all of the twelve pitch classes approximately equally. The term "pitch class" is from musical set theory, and basically refers to one of the twelve pitches of the equal-tempered chromatic scale, disregarding octaves; for example, the pitch class C consists of the Cs in all octaves.

My method of choice was the pitch class histogram, specifically its "folded fifths" variant which orders the histogram bins according to the cycle of fifths. This ordering "is useful for measuring dominant-tonic relationships and for looking at types of transpositions" according to the documentation for a popular music analysis library called jSymbolic. A modal composition--one that confines itself to a single key--will occupy seven consecutive bins of the folded fifths histogram, making it easy to identify.

A perfectly atonal composition would produce a histogram in which all twelve bars have exactly the same height. This would indicate that the composition's notes are distributed equally among the twelve pitch set classes, or put another way, that each pitch class comprises one twelfth (8.33%) of the composition's notes. This situation is unlikely in practice, but the more closely a composition resembles this idealized case, the more atonal it is.

I had long suspected that "Atunwi" and "Ero Ayo" are my most atonal compositions, and the histograms confirm this. But there were surprises too, for example the "Apologize to the Future" album is more atonal than I realized, particularly the tracks "Overshoot" and "Singularity." The chronological ordering of the albums reveals my gradual cultivation of atonality, starting with "Fazo Kanto" on "Akojo Ajeji."

I looked into using jSymbolic, but decided to roll my own code, in part because I was reluctant to risk installing the Java framework, but also because the primary goal was learning. The chart drawing was done via the Plotly Javascript library, which is free and open source and heartily recommended.