To invert any interval, simply imagine that one of the notes has moved one octave, so that the higher note has become the lower and vice-versa. Because inverting an interval only involves moving one note by an octave (it is still essentially the "same" note in the tonal system), intervals that are inversions of each other have a very close relationship in the tonal system.
To find the inversion of an interval
- To name the new interval, subtract the name of the old interval from 9.
- The inversion of a perfect interval is still perfect.
- The inversion of a major interval is minor, and of a minor interval is major.
- The inversion of an augmented interval is diminished and of a diminished interval is augmented.
What are the inversions of the following intervals?
- Augmented third
- Perfect fifth
- Diminished fifth
- Major seventh
- Minor sixth