Understanding Interval Inversions

This article assumes you are already familiar with intervals. For a review of intervals please read these three previous articles:

• Understanding Intervals
• Major Intervals
• Perfect Intervals

Compound Intervals

All compound intervals can be reduced to a simple interval by moving the higher note down so that it is within an octave of the lower note. For example a Major 9th functions in most cases like a Major 2nd and includes the same two note names. The only difference is the octave number. So, in most situations, compound intervals are described using the simple interval description.

Interval Inversions

With any two different notes you can build two different intervals. For example, an F and an A can be either a M3 or a m6.

These two intervals are closely related in sound and have a special relationship to each other. To create a harmonic inversion the bottom note can be moved up an octave or the top note can be moved down an octave.

There are some special characteristics of inversions:

• The interval plus its inversion add up to nine.
• Perfect intervals always stay perfect.
• Major intervals become Minor and Minor intervals become Major.
• Augmented intervals become Diminished and Diminished intervals become Augmented.

Notice how this works in the examples below.

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