Chord Inversions

Chord inversions play a crucial role in harmony, adding variety and depth to music by changing the bass note of a chord to something other than its root. An inversion essentially reorders the notes of a chord so that a different chord tone becomes the lowest note. The lowest note always determines the voicing. Understanding chord inversions not only helps in achieving smoother voice leading and bass lines but also in enriching the harmonic texture of a piece. Playing chords with different roots in the bass creates a sense of space and distance as you go from root position and place the 3rd, 5th or 7th as the root of the chord.

For triads there are 3 positions and two inversions. Root position consist of the root in the bass. This is a sense of being rooted and close to home. Second position or first inversion consist of the third in the bass; this creates a little distance from home. Third position or second inversion consist of the fifth in the bass; this creates more distance from home and really opens up the harmonic expression.

To know when to play a particular note for a chord in the bass, we use numbers in the shorthand harmonic notation to communicate which note is in the bass. Here is a visual representation of the shorthand harmonic notation of chords first showing C in root, first inversion, and second inversion, and second shown playing C in root position but changing the bass note.

The reason we use 5/3, 6/3, and 6/4 to denote a root, 3rd, or 5th in the bass is because of the interval created when playing the chords in root, first inversion, or second inversion. In root position there is a perfect fifth between the root and the top note and a 3rd between the root and the second note; you normally don’t write 5/3 you just write the chord and assume it is in root position if not otherwise denoted. In first inversion, there is a 6th between the root and the top note and a 3rd between the root and the second note so we use 6/3 to denote a 3rd in the bass. In second inversion, there is a 6th between the root and the top note and a 4th between the root and the second note; so we use 6/4 to denote a 5th in the bass. Here is a visual representation of the intervals created by the chord in different positions.

For tetrads it follows the same principle as triads but it adds the seventh to the chord. So root position, is denoted as 753 or the root in the bass. Second position or first inversion is denoted as 653 or the 3rd in the bass. Third position or second inversion is denoted as 643 or the 5th in the bass. Fourth position or third inversion is denoted as 642 or the 7th in the bass.