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Interval Inversion – Definition
An interval inversion is created by moving one note of an interval up or down by an octave, causing the lower note to become the higher note, or vice versa.
What is an Interval Inversion?
When an interval is inverted, its name changes while maintaining a mathematical relationship to the original interval. A useful rule is the Rule of Nine: the numbers of an interval and its inversion always add up to nine. For example, a third becomes a sixth, and a fourth becomes a fifth.
The interval quality also changes during inversion. Major intervals become minor, minor intervals become major, augmented intervals become diminished, diminished intervals become augmented, and perfect intervals remain perfect.
How is an Interval Inversion used in piano playing?
Understanding interval inversions helps pianists recognize interval relationships across the keyboard and improve voice leading between chords. Closely related intervals often allow smoother movement from one chord to the next.
Interval inversions are also useful in ear training, music theory, and harmonic analysis, helping pianists understand the structure of melodies, chords, and musical textures.