The Chromatic Scale

The movement of a melodic line against an ison creates a rich harmonic texture, especially when compared to the monophonic unisonal singing that preceded it. This necessitates a more advanced form of harmonic analysis.

Intervals can now be grouped into different categories: perfect, major, and minor. It cannot be stressed enough that the generic interval (unison, second, third, fourth, fifth, sixth, seventh, octave) must be identified first, before identifying the harmonic quality (perfect, major, minor.) Many a music theory student has incorrectly named an interval by neglecting this first step.

That caveat in place, octaves, fifths, and fourths (the intervals naturally occurring as the first four tones of the harmonic series at frequency ratios of 1:2, 2:3, and 3:4) are known as perfect intervals.

By contrast, seconds, thirds, sixths, and sevenths, have both a major version and a minor version. In all cases, the major interval is one semitone higher than the minor interval.

The table below shows you whether an interval is minor (m), major (M), or perfect (P) based on the number of semitones (row) and generic interval (column.)