Four-Part Writing: Distributing Harmony Across Voices

Core Idea

Four-part SATB writing distributes a three-note harmony (triad or seventh chord) across four voices by selecting which chord member appears in each voice and deciding which to double. Each voice must maintain its own melodic integrity while the four voices together create the intended harmony. Spacing, doubling, and voice leading work together to achieve a coherent whole.

How It's Best Learned

Start with chord symbols and Roman numerals, then systematically voice each chord by selecting what each voice sings, checking spacing and doubling conventions, and verifying smooth voice leading between chords.

Explainer

The central puzzle of four-part writing is that triads have three distinct pitches but SATB texture requires four voices. Every triad you write will have one pitch appearing twice — the doubled note. Which note you double, and how you distribute the remaining pitches across soprano, alto, tenor, and bass, determines the chord's balance, resonance, and voice-leading flexibility. Learning to make these decisions systematically is the core skill of this topic.

The general rule for doubling is: double the root in root-position chords, especially for tonic and dominant harmonies. The root is the most stable note of the chord, so duplicating it adds stability without creating voice-leading problems. Doubling the fifth is also usually safe. Doubling the third is generally avoided for major or minor triads because the third carries more color (it distinguishes major from minor), and having two voices sing the same color note creates imbalance. One critical exception: for diminished triads (especially the leading-tone chord, vii°), double the third rather than the root or fifth, because the leading tone (root of vii°) and the diminished fifth (b5) both want to resolve by step and should not be doubled — doubling tendency tones creates parallel resolutions that violate voice-leading rules.

Spacing is the second structural decision. In close position, the upper three voices (soprano, alto, tenor) are packed within an octave of each other. In open position, they are spread across two octaves. Both positions are correct in different contexts. The single firm rule is that the distance between soprano and alto, and between alto and tenor, should not exceed an octave — but the distance between tenor and bass can be larger, sometimes a tenth or twelfth, without sounding imbalanced. This is because the bass acts as a harmonic foundation rather than a melodic partner to the tenor.

The most important downstream consequence of distribution decisions is voice leading. A voicing that puts two voices close together at the start may make smooth continuation difficult or produce forbidden parallels. Before finalizing a chord, mentally trace where each voice will go next: does soprano have a reasonable melodic step or small leap to the next chord? Does the bass move by the required interval? Do any pairs of voices move in parallel perfect intervals? These questions make voicing a prospective decision, not just a retroactive one. Good SATB writers don't just voice the current chord — they voice it in anticipation of where the next chord will need each voice to arrive.