Locking Harmony
Lock the progression by scale degree and check the bass, knowing that too much locking flattens the melody.
Related
Right chord names, scattered voices
Write C–G–Am–F and the chords arrive correct while the bass climbs every bar and the chorus never lifts. Locking harmony is not just getting roots right; it covers inversions, bass motion and how long each chord lasts. Given names alone, the model picks its own voicings, so the harmony is right and the voices are a mess.
Lock the progression with scale degrees
State the key, then the degrees: C major, I–V–vi–IV, two beats each. Degrees hold better than chord names because they survive transposition and keep the model inside the key. To tighten further, specify the bass: the lowest note of each bar on the root, or in first inversion. The bass is the quickest place to check harmony; when inner voices are hard to hear, follow the lowest note bar by bar.
Writing modulations and borrowed chords
| Goal | How to write it | Usual problem | Check |
|---|---|---|---|
| Fixed four-chord loop | Key plus degrees, with beats per chord | Random inversions, jumping bass | Lowest note in each bar |
| Chorus modulation | State the whole-step lift and a two-bar common-chord transition | Hard cut, broken seam | Find the chord shared by both keys |
| Borrowed minor subdominant | Name iv and where it appears | Treated as a wrong note | Does the fourth degree flatten |
| Chromatic bass line | Spell the bass beat by beat | Extra chords appear | Count chords per beat |
The safest modulation is written as a transition: introduce a chord shared with the new key in the last two bars of the old one, then land on the new tonic. A borrowed chord needs a function, such as iv to I at the end of a verse, which survives better than a bare chord name.
What locking costs
The tighter the harmony, the more the melody is pressed into chord tones and the more the rhythm becomes one chord per beat. Locking an entire song also costs the bass its counterpoint, until verse and chorus differ only in instrumentation. A workable compromise locks two bars at each section boundary plus the bass, and leaves the rest open; another is to lock harmony for the first pass and rewrite the melody separately. When locking fails, check that the stated key stays consistent, then check whether two conflicting references were supplied at once.
Listen in the library
All tracks from midicn-lib — inline badge is the license tier (C1 commercial / C2 non-commercial / C3 study only).
Along the same line
Sources
- Walter Piston, Harmony（Norton）与 Aldwell & Schachter, Harmony and Voice Leading 中关于级数、转位与转调的写法。
- 文本条件中的调性与和弦表达，依据公开模型文档。