Saturday, March 19, 2016

How to Determine Chord Inversion Numbers

Chord inversion numbers confuse many music students. Remember that inversions are determined by counting the distance between the bass note and the upper notes. In an A6 chord, because the A is on top and the C is in the bass, there is a distance of a sixth between the two notes. This is why we identify an A6 as a first inversion chord. Counting the numbers between the bass note and all of the other notes gives you the total numbering scheme for the chord. Numbers will be left out if they are not necessary to distinguish them from other chords.

Triads


Step 1: Condense the chord into the smallest spacing without changing the bass note. The bass note determines what type of inversion you have. If you move the bass note, you can't tell what the inversion is.

Step 2: Determine whether the root of the chord is in the bass. The root is the note that defines the chord name. For instance, C major has a C as the root. If the root is in the bass, the chord is in root position and is considered a 5/3. Because it is in root position, however, the numbers are not used.

Step 3: Determine whether the 3rd of the chord is in the bass. If the 3rd is in the bass, you have a chord in first inversion. The first inversion numbering scheme is 6/3. However, it is labeled as a 6 because the 3 is unneeded information. Step 4 Determine whether the 5th of the chord is in the bass. If the 5th is in the bass, the chord is in second inversion. The numbers for a chord in second inversion are 6/4.

Seventh Chords


Step 1: Condense the chord into the smallest spacing possible while keeping the bass note in the same location.

Step 2: Determine whether the root of the chord is in the bass. If so, it is a root position seventh chord. The number for this chord is 7/5/3. However, it is spelled as a 7.

Step 3: Determine whether the 3rd of the chord is in the bass. If it is, then you have a first inversion seventh chord. The number system is 6/5/3; however, only 6/5 are used to identify the chord.

Step 4: Determine whether the 5th of the chord is in the bass. If it is, then you have a second inversion triad. The number system for second inversion triads is a 6/4/3. However, as this could be confused with the second inversion triad, only the numbers 4/3 are used to indicate this seventh chord.

Step 5: Determine whether the 7th of the chord is in the bass. This indicates there is a third inversion triad. The 7th in the bass is rare and is spelled 6/4/2. However, to avoid confusion with the second inversion triad, it is written as 4/2.

To put chords in their smallest spacing, arrange them so that no other chord tone could fit between any of the other pitches. Make sure to keep the bass note in the bass.