Inverting Intervals

An inversion is a melodic or motivic transformation in which successive ordered pitch intervals reverse directions. In other words, an inversion reverses the order of high vs. low in an interval. If you are given the interval of F4 to C5, you would invert it by changing it to C5 to F5.

When adjusting the quality of an inverted interval…

           Perfect stays perfect

           Major changes to minor

           Minor changes to major

           Augmented changes to diminished

           Diminished changes to augmented

When adjusting the distance of an inverted interval, 9 is your magic number. If you begin with a 5th, the inversion will be whatever you need to add to get 9. In other words, 5 + __ = 9. Therefore, the inversion of a 5th is a 4th.

G to E is a M6. To invert it, first change the quality from Major to minor. Then, find the new distance by solving 6 + ___ = 9. Because 6 + 3 = 9, the inversion of a M6 is a m3. This is confirmed when we switch the notes on the staff because E to G is a m3.

So far, we have only talked about harmonic intervals and ascending melodic intervals. What changes if we encounter a descending melodic interval, though? The overall message for these is that nothing changes!

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Still ascertain the interval by looking at the major key of the lowest pitch. If you are unclear, re-stack the notes as a harmonic interval instead of a melodic interval. Then, identify them by the key of the lowest note.

Descending Intervals

If you have to write a descending melodic interval, you can use the inversion to help you. For instance, if you need to write a M3 below C, ask yourself what a m6 above C is (i.e the inversion). You should come up with Ab. Then, just move the note Ab below C instead of above.