If you’re given a harmonic progression with inversion figures (6, 4/2, etc.), checking for errors involves checking root movements and chord-class movements between harmonies, as well as if the figures specify poor voice leading in the implied bass line. The errors fall into the following categories:
- disallowed root movements
- disallowed chord class movements
- improper use of 6/4 chords (not a passing, pedal, or cadential)
- unresolved chordal sevenths
- unresolved leading tones
Your error checking should be methodical. Check for errors in each category, one category at a time.
For example, poor root movements would include descending seconds and ascending thirds. Disallowed chord class movements would involve D-Class chords moving to S-Class chords (V moving to ii or IV), or D-Class chords with a root moving down a third (V to iii).
6/4 chords must function as one of the three 6/4 types: passing, pedal, or cadential. If the 6/4 chord is properly used as a cadential type, it must occur on a strong beat and must resolve immediately to V or V7. Passing 6/4 chords must be part of a three-note stepwise bass pattern in a single direction, and occur between two chords of the same class (which includes the same harmony).
The other figure errors apply only to the bass line implied by the figures. You won’t be able to know if a leading tone or chordal seventh goes unresolved in an upper voice. For the chordal seventh to be an issue, the chord must be in 4/2 position. Third inversion seventh chords (4/2) must be followed by a harmony and figure that allows the seventh in the bass to resolve down by step. Such 4/2 chords are usually followed by first inversion chords, with a root movement of a descending fifth (V4/2 – I6, ii4/2 – V6 or V6/5, etc.). The leading tone will only be in the bass and need to be resolved if the harmony/figure combination is V6, V65, or vii°7. All of these chords must resolve to a root position I chord.