Figure 4
From: Heaps’ law and vocabulary richness in the history of classical music harmony
Vocabulary relative richness R for each composer in chronological order. Horizontal axis is birth \(+\, 20\, +\) death, divided by 2. The straight line is a linear regression with slope \(0.72\pm 0.04\) “units of richness” per century and a linear correlation coefficient \(\rho =0.90\) (and intercept −12.9). Some particular composers are highlighted, for the sake of illustration