Getting Started
Second-inversion triads, or 6/4 chords, are harmonically unstable and must be handled with specific voice-leading procedures. While there are several contexts in which they can appear, the most common and structurally important is the cadential 6/4 chord. This chapter focuses on identifying this chord and mastering the strict voice-leading rules that govern its use as an embellishment of the dominant harmony at a cadence.
What You Should Be Able to Do
Identify the four types of 6/4 chords (cadential, passing, neighboring, arpeggiated) in a musical score.
Provide a correct Roman numeral analysis for a cadential 6/4 chord, showing its relationship to the dominant chord it precedes.
Analyze the voice leading of a cadential 6/4 chord to confirm that all voices resolve correctly according to 18th-century practice.
Detect and correct part-writing errors in progressions involving cadential 6/4 chords, such as incorrect resolutions or doublings.
Compose a four-part harmonic progression that correctly employs a cadential 6/4 chord to approach a cadence.
Key Concepts & Analysis
The treatment of 6/4 chords is governed almost entirely by voice-leading conventions. Because the interval of a perfect fourth above the bass is considered a dissonance in this context, second-inversion chords cannot be used as freely as root-position or first-inversion chords. Their usage is restricted to a few specific patterns where this dissonance is carefully controlled and resolved.
The Instability of the 6/4 Chord
A second-inversion triad, commonly called a 6/4 chord, is a triad with its fifth in the bass. The name "6/4" comes from the generic intervals formed by the upper voices above this bass note: a sixth and a fourth. In common-practice harmony, the interval of a fourth above the bass is treated as a dissonance that requires resolution, which is the movement of a dissonant note to a consonant one. This inherent instability means that 6/4 chords are not functional harmonies in their own right but rather serve as passing or decorative events.
While there are four established contexts for using 6/4 chords, our focus here is on the most significant: the cadential 6/4.
The Voice Leading of the Cadential 6/4
The cadential 6/4 chord is a specific voice-leading pattern that occurs on a metrically strong beat to embellish a dominant chord, almost always at a cadence. Although it is spelled as a tonic triad in second inversion (with scale degree ^5 in the bass), it does not have a tonic function. Its entire identity is defined by the way it resolves to the dominant chord that follows it.
The procedure is strict and predictable:
The Bass Note: The bass note of the cadential 6/4 is always scale degree ^5, the same note that will be the root of the dominant chord. This bass note is sustained or repeated from the 6/4 chord into the dominant chord.
The Upper Voices: The two upper voices that form the intervals of a sixth and a fourth above the bass must resolve down by step.
The note a sixth above the bass (scale degree ^3) resolves down by step to become the fifth of the dominant chord (scale degree ^2).
The note a fourth above the bass (scale degree ^1) resolves down by step to become the third of the dominant chord (scale degree ^7, the leading tone).
Doubling: In a standard four-part texture, the most common practice is to double the bass note (scale degree ^5). This doubled note is held constant through the resolution, creating two stationary voices that anchor the progression.
Roman Numeral Analysis
Because the cadential 6/4 functions as a decoration of the dominant, not as a true tonic, its analysis can be shown in two ways.
I(6/4) – V: This notation is simple and clearly identifies the notes present in the chord (a tonic triad). However, it is functionally misleading, as it implies a tonic function that does not exist.
V(6/4–5/3): This notation is functionally superior. It treats the entire event as a single, expanded dominant harmony. The figures
6–5and4–3are written below the Roman numeralVto show the required stepwise downward resolution of the upper voices. For simplicity, this is often abbreviated to just V(6/4) – V. This method accurately reflects the chord's role as an embellishment.
The cadential 6/4 chord's placement on a strong beat, followed by its resolution to the V chord on a weaker beat, creates a suspension-like effect that heightens the arrival of the dominant.
Data & Organization Tools
The voice-leading procedure for a cadential 6/4 chord is invariable. The following table illustrates the precise movement of each voice, using C major as an example.
Voice-Leading Procedure for the Cadential 6/4
| Voice | Scale Degree (in C major) | Interval above Bass | Resolution |
|---|---|---|---|
| Bass | ^5 (G) | (Bass Note) | Stays on ^5 (G) |
| Upper Voice 1 | ^3 (E) | 6th | Resolves down to ^2 (D) |
| Upper Voice 2 | ^1 (C) | 4th | Resolves down to ^7 (B) |
| Doubled Voice | ^5 (G) | 8ve (or Unison) | Stays on ^5 (G) |
Evidence Bank
Cadential 6/4 Chord: A second-inversion tonic triad that resolves to a root-position dominant chord. It functions as a dominant embellishment and occurs on a metrically strong beat.
Second-Inversion Triad: A triad whose fifth is in the bass, creating the intervals of a 6th and a 4th above the bass.
Voice Leading: The art of combining individual melodic lines to create a coherent harmonic progression. The rules of voice leading govern the movement of each part.
Resolution: The mandatory movement of a dissonant note or chord to a consonant one, providing a sense of release from harmonic tension.
Metric Placement: The position of a chord in relation to the strong and weak beats of a measure. The cadential 6/4's placement on a strong beat is essential to its identity.
V(6/4–5/3) Notation: A functionally descriptive Roman numeral analysis that shows the cadential 6/4 and its resolution as a single dominant event.
Passing 6/4 Chord: A 6/4 chord where the bass note is part of a stepwise melodic line, typically connecting a root-position chord with its first inversion (e.g., I – V(6/4) – I(6)).
Neighboring (or Pedal) 6/4 Chord: A 6/4 chord where the bass note is stationary while two upper voices move stepwise and then return (e.g., I – IV(6/4) – I).
Skill Snapshots
Functional:
IV – V(6/4) – V – I: A classic progression where a pre-dominant chord moves to the cadential 6/4.ii(6/5) – V(6/4) – V – I: A common minor-key progression (or major-key with a ii7) leading to the cadence.I – V(6/4) – V – I: A simple but effective progression that emphasizes the tonic notes within the 6/4 chord.
Voice-Leading:
Rule: The 4th above the bass must resolve down by step. Effect: This resolves the primary dissonance against the bass and creates the crucial leading-tone (^7) of the dominant chord.
Rule: The 6th above the bass must resolve down by step. Effect: This ensures smooth, conjunct motion in an upper voice, moving from scale degree ^3 to ^2.
Rule: The bass note (scale degree ^5) is sustained or repeated. Effect: This provides stability and clarifies the chord's function as an elaboration of the dominant harmony.
Form:
Baseline Phrase: A phrase ending in a perfect authentic cadence is often strengthened by using the
V(6/4) – V – Iprogression to build tension before the final tonic.Contrast: A phrase ending in a half cadence may also use the cadential 6/4, stopping on the V chord:
...ii(6) – V(6/4) – V.Continuity: The strong-beat placement of the dissonant 6/4 chord creates rhythmic and harmonic momentum, demanding forward motion and making the resolution to the V chord feel both necessary and inevitable.
Common Misconceptions & Clarifications
Misconception: The I(6/4) chord has a tonic function because it uses the notes of the tonic triad.
- Clarification: Function is determined by context, not just spelling. The cadential 6/4's instability, metric placement, and mandatory resolution to V give it a dominant-prolonging or dominant-embellishing function.
Misconception: The bass of a cadential 6/4 chord can move by step or leap.
- Clarification: The bass of the cadential 6/4 is always scale degree ^5 and must be sustained or repeated to become the root of the following V chord. Any other bass motion would violate its definition.
Misconception: The 6th and 4th above the bass can resolve upwards or by leap.
- Clarification: The defining voice-leading characteristic of the cadential 6/4 is the downward, stepwise resolution of both the 6th and the 4th. Any other resolution negates its identity.
Misconception: Any 6/4 chord built on scale degree ^5 is a cadential 6/4.
- Clarification: To be a cadential 6/4, the chord must also appear in a metrically strong position and resolve correctly to a V or V7 chord. A 6/4 chord on ^5 that is part of a simple arpeggiation (e.g., I – I(6) – I(6/4)) is an arpeggiated 6/4, not a cadential one.
Summary
The cadential 6/4 chord is a specific and highly regulated harmonic event used to embellish the dominant chord at a cadence. Despite being spelled as a tonic triad in second inversion, it does not possess a tonic function. Its identity is rooted in its voice leading: it appears on a metrically strong beat with scale degree ^5 in the bass, which is sustained into the following dominant chord. The upper voices, a sixth and a fourth above the bass, must both resolve down by step to form the notes of the V chord. Mastering this precise procedure is essential for analyzing, writing, and understanding one of the most powerful conventions of tonal harmony.