Section 5.5 Augmented and Diminished Intervals¶
Augmented intervals are one half step larger than perfect or major intervals and diminished intervals are one half step smaller than perfect or minor intervals.
Remember that perfect intervals (unisons, fourths, fifths, and octaves) can never be major or minor, and major and minor intervals (seconds, thirds, sixths, and sevenths) can never be perfect in quality. However, any size of interval can be augmented or diminished.
Here are musical examples illustrating the continuum of interval quality.