Biblioteca de la Guitarra y Cuerda Pulsada

It is proposed that two different harmonic systems govern the sequences of chords in popular music: affordant harmony and functional harmony. Affordant chord transitions favor chords and chord transitions that minimize technical difficulty when performed on the guitar, while functional chord transitions favor chords and chord transitions based on a chord's harmonic function within a key. A corpus analysis is used to compare the two harmonic systems in influencing chord transitions, by encoding each song in two different ways. Songs in the corpus are encoded with their absolute chord names (such as “Cm”) to best represent affordant factors in the chord transitions. These same songs are also encoded with their Roman numerals to represent functional factors in the chord transitions.

The total entropy within the corpus for both encodings are calculated, and it is argued that the encoding with the lower entropy value corresponds with a harmonic system that more greatly influences the chord transitions. It is predicted that affordant chord transitions play a greater role than functional harmony, and therefore a lower entropy value for the letter-name encoding is expected. But, contrary to expectations, a lower entropy value for the Roman numeral encoding was found. Thus, the results are not consistent with the hypothesis that affordant chord transitions play a greater role than functional chord transitions. However, post hoc analyses yield significant results consistent with two other more moderate claims: first, affordant chord transitions do influence the chord sequences of popular music, although not as much as functional chord transitions; second, the relative influence of affordant versus functional factors on chord transitions has increased since the 1950s. Lastly, the corpus was refined to include only songs composed by guitarists and performed by its composers, and it was found that affordant chord transitions played a greater role in these songs.

Affordant Chord Transitions in Selected Guitar-Driven Popular Music