Notice that 4th's, 5'ths, 1's, and 8ve's are never
major or minor. They can
only be perfect, augmented or diminished.
When intervals are altered, their quality changes.
If a major or perfect interval is increased in size by one half step it
If a major interval is decreased in size by one
half step, it becomes minor.
If a minor or perfect.interval is decreased in size by one half step,
it becomes diminished.
The following chart shows the relationships between
Each space between interval quality represents a change of a half step.
For seconds, thirds, sixths and sevenths:
From left to right, interval is increasing in size
by one half step.
For fourths, fifths, unisons, and octaves:
From left to right, interval
is increasing in size by one half step.