Harmonizing Melody: Voice Leading Choices

Core Idea

Harmonizing a melody requires selecting appropriate chords that support the melody and then voicing those chords with smooth voice leading. The melody note should appear in an appropriate voice (usually soprano), and the remaining voices must complete the harmony while following spacing, doubling, and motion rules. Multiple correct harmonizations may exist for the same melody, each creating a different harmonic context. Voice leading considerations often determine which harmony is most effective.

How It's Best Learned

Choose a simple melody (hymn tune or folk song) and write multiple harmonizations for the first phrase, comparing how different chord choices and voice leading create different effects. Analyze existing harmonizations to reverse-engineer the decision process.

Explainer

When you harmonize a melody, you are working with a constraint hierarchy. The melody is fixed — it is your given. Harmonic function (from your study of tonic, pre-dominant, and dominant functions) narrows the field of plausible chords for each melody note. And finally, voice leading decides among the remaining options by favoring the progression that keeps lower voices moving smoothly. These three layers — melody, function, voice leading — interact at every chord choice, and the most effective harmonizations are those where all three align.

Start with the melody note's membership in potential chords. A melody note of E in C major could belong to the I chord (as the third), the iii chord (as the root), the IV chord (as the major seventh, if you include extensions), the vi chord (as the fifth), or potentially as a non-harmonic tone over other chords. That is a lot of options. Harmonic function prunes this list: at a phrase ending, you need a cadential formula (typically dominant–tonic or half-cadence on V). Mid-phrase, you need harmonic motion that propels forward without settling prematurely. The T–PD–D–T framework from your harmonic function study provides the roadmap: tonic chords establish, pre-dominants move away, dominants create tension, tonic returns for resolution. When a melody note can support a chord that serves the right function at the right moment, that is a strong candidate.

Voice leading then evaluates candidates by their smoothness in context. Suppose at a particular moment both IV and ii6 would support the melody note and serve pre-dominant function equally well. The tie-breaker is how the lower voices arrive at each option and depart from it. If the alto and tenor can reach the ii6 chord by step from the previous chord but would require a leap to reach IV, the ii6 is probably better voice-leading. If the IV chord creates a particularly smooth bass line by contrary motion to the soprano, it may be preferred. The point is that this decision is not arbitrary — it follows from the principle you already know: prefer contrary motion, minimize leaps, resolve tendency tones, avoid parallel perfect intervals.

The soprano voice's harmonic position matters too. When the melody note is the root of the chord (root position in soprano), the harmony feels stable and direct. When the melody note is the third (third in soprano), the harmony feels softer and slightly open. When the melody note is the fifth (fifth in soprano), the effect depends on context — it can sound noble in a perfect authentic cadence, or slightly ambiguous mid-phrase. Learning to choose a chord inversion partly based on what melodic position the soprano occupies is an advanced harmonization skill: a final cadence where the soprano lands on scale degree 1 (the root) over a root-position I chord sounds conclusive; landing on 3 or 5 sounds incomplete, which may be exactly what you want for a half-cadence or an interior phrase ending.

Multiple harmonizations of the same melody are not only possible but illustrative. Bach harmonized many of the same chorale melodies multiple times over his career, and the different harmonizations illuminate how the same melodic constraints can support different expressive narratives. The melody that ends on E in C major might be harmonized I in the first version (landing on the third, soft ending), iii in a second version (more modal color), or even as a deceptive cadence (V–vi, where E appears as the third of vi). Studying multiple harmonizations of the same melody teaches you more about voice leading and harmonic function than any amount of abstract rule-following, because it makes visible the web of decisions behind each option.