Interval Qualities
While we have established to basic way to describe an interval sharpening and flattening the beginning or ending note will change the intervals quality.
Qualities
- Diminished – d
- Minor – m
- Major – M
- Perfect – P
- Augmented – A
Seconds, Thirds, Sixths and Sevenths can be major or minor, but not perfect.
Unisons, Fourths, Fifths, and Octaves can be perfect but NOT major or minor.
When you flatten a major interval – or make it one half step smaller – it becomes minor, and when a major interval is flattened twice it becomes diminished.
A minor interval becomes diminished if it is flattened by one half step and it becomes major if it is raised by one half step.
Perfect intervals become diminished when they are lowered by a half step. Conversely, Perfect intervals become augmented when they are sharpened or raised by a half step.
It is also possible to be doubly augmented or doubly diminished.
Perfect Intervals remain the same in the major keys and their relative minor keys.
Inverting Intervals
The key rule to remember with inverting intervals is that the inversion plus the original interval will always add up to nine and the qualities always flip except for perfect intervals; perfection will always remain that way.
Inversions:
- Diminished – Augmented
- Minor – Major
- Major – Minor
- Augmented – Diminished
- Perfect – Perfect
One helpful use of inverting intervals is found in sight singing. When you have a larger interval you can sing the lower note up an octave so the interval is much easier to find. Once you find the smaller interval you can invert it and find the original interval.