19 Interval Quality
Once the size of the interval has been determined, the quality can be found. The easiest way to determine the quality is to start by examining the intervals found in the major scale.
In the image above, there is now a distance and a quality. The distance is found using the methods found in the last section, and the two qualities found here are major and perfect. The major quality is applied to the intervals of a second, third, sixth, and seventh, whereas the perfect quality is found on the fourth, sixth, and eighth.
Major and perfect intervals are found when both the bottom and top notes follow the key signature of the bottom note.
Example
When identifying this interval, we count from D to F (3). We then look at the key signature for D Major, which is F𝄰 and C𝄰 . Because the F𝄰 belongs in the key of D Major, this interval is a major third.
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Exercises
In addition to the major and perfect qualities, there are three other qualities to discuss, and all of them can be created by altering one of the major or perfect intervals found in the major scale.
When a major interval has its top note lowered by one semitone, the quality changes from major to minor. This is possible on Ma2, Ma3, Ma6, and Ma7.
When the top note of a perfect interval is lowered by one semitone, the interval quality becomes diminished.
When either a major or perfect interval is made larger by raising the top note by one semitone, the interval becomes augmented.
Exercise
Add the accidentals to create the correct interval.
When naming intervals, the bottom note (the root), quality, and distance are all given in that order. For example, in the image, the root of the interval is A♭, the quality is major, and the distance is a third. The name of this interval is A♭ ma3.
Intervals
Video 19.1 Intervals [Video transcript – See Appendix B 19.1]
