Fig. 4: Scale interval-sizes across all scales (semi-automated) in the vocal corpus.
From: Musical scales optimize pitch spacing: a global analysis of traditional vocal music
A The probability density of interval-sizes is shown continuously, with a bin size of 0.2 semitones. The mean value is 2.2 semitones, with a positive skew. B The probability density of interval-sizes is shown categorically up to the size of a perfect fourth (5 semitones), where the category boundaries for each interval are shown in parentheses in semitones.
