Harmony & Voice Leading IV: Secondary Function

What this unit covers

The topics below follow the published Music Theory course framework for Unit 7. Music Theory publishes no per-unit weighting, so there is no percentage to chase here.

Lessons in this unit

• Secondary Dominants15 min · 3 objectivesExplain tonicization and how a secondary dominant borrows a leading tone · Spell secondary dominants such as V/V, V/ii, and V/vi · Resolve a secondary dominant to its temporary tonic
• Secondary Leading-Tone Chords14 min · 3 objectivesBuild secondary leading-tone triads and seventh chords (vii°/x, vii°7/x) · Distinguish fully-diminished from half-diminished secondary function · Resolve secondary leading-tone chords to their target

Formulas in Unit 7

Every term in Unit 7

All 18 terms we publish for Harmony & Voice Leading IV: Secondary Function, with definitions. Reading them through is the fastest way to find the ones you cannot define — then drill those in cram mode until you can produce them without the prompt.

What a secondary dominant is

A major-minor chord borrowed from another key that tonicizes a diatonic chord. V/V in C major is D–F♯–A–C, and the F♯ is the borrowed leading tone.

Spelling any secondary dominant

Find the target chord's root, build a major triad or dominant seventh a fifth above it, then apply the accidental needed. The accidental is almost always a raised note.

Which chords can be tonicized

Any diatonic major or minor triad. You cannot tonicize vii° in major or ii° in minor, because a diminished triad cannot function as a tonic.

Secondary leading-tone chords

vii°/x and vii°7/x resolve to their target like vii° resolves to I. Common as vii°7/V, which resolves to V.

Resolving a secondary dominant

Its leading tone rises to the target root and its seventh falls by step. Failing to resolve the raised note is the most common error with these chords.

Tonicization vs modulation

Tonicization is momentary and has no cadence in the new key; modulation is confirmed by a cadence and persists. A single V/V is not a modulation.

Deceptive resolution of a secondary dominant

V/vi resolving to IV rather than vi, for instance. Legal and expressive, and should be labeled by what actually follows.

V/V and the raised fourth

In C major, V/V requires F♯. That raised fourth is the audible signal of secondary function on the aural exam.

Applied chords in minor

V/III, V/iv, V/V and V/VI are common. Tonicizing III in minor moves toward the relative major and is a frequent structural device.

Modal mixture (borrowed chords)

Chords borrowed from the parallel mode — iv, ♭VI, ♭VII, ii° in a major key. They darken the color without changing the key.

Picardy third in context

A minor-key piece ending on a major tonic. Standard in Baroque practice and heard as an unexpected brightening at the final cadence.

Neapolitan sixth

A major triad on the lowered second degree, nearly always in first inversion, labeled N6 or ♭II6. Functions as a predominant and typically moves to V or to a cadential six-four.

Voice leading the Neapolitan

Double the bass, which is scale degree 4. The lowered 2 in the upper voice falls to the leading tone, producing a diminished third that is idiomatic here.

Italian, French and German augmented sixths

All contain ♭6 and ♯4. Italian adds the tonic, French adds scale degree 2, German adds ♭3. All resolve outward to the dominant octave.

The German sixth problem

Resolving It directly to V produces parallel fifths, so it usually passes through a cadential six-four first. This is the specific reason the cadential six-four appears where it does.

Hearing chromatic harmony

Listen for a note outside the key that then resolves by half step. That is a secondary function; a chromatic note that does not resolve is more likely mixture.

Labeling secondary function

Write the numeral of the borrowed chord, a slash, then the numeral of the target: V6/5/ii. The chord after the slash must actually appear or be implied.

Common secondary progressions

I–V/V–V–I, I–V/vi–vi–ii–V–I, and the chain V/V–V–V/vi–vi. Recognizing these by ear covers most of what the exam asks.

What examiners penalize here

• To analyze any chromatic chord, ask: "**Does its chromatic tone lead into the root of the next chord by half step?**" If yes, it is very likely a secondary dominant of that next chord. Label it V/x (or V7/x), where x is the Roman numeral of the tonicized chord in the home key.
• When you find a **fully diminished seventh** in the middle of a phrase, test it as a **secondary leading-tone chord**: its root is a half step below the next chord’s root, and it resolves there. Because it is symmetrical, spelling (which note is the root) tells you which chord it tonicizes.

Practice Music Theory

Our practice bank is drawn from across the whole course rather than filtered to one unit, which is closer to how the exam asks anyway — it will not tell you which unit a question is testing.

Questions about this unit

All 8 units of AP Music Theory

1. Unit 1 · Music Fundamentals I: Pitch, Major Scales & Key Signatures, Rhythm, Meter
2. Unit 2 · Music Fundamentals II: Minor Scales & Key Signatures, Melody, Timbre & Texture
3. Unit 3 · Music Fundamentals III: Triads & Seventh Chords
4. Unit 4 · Harmony & Voice Leading I: Chord Function, Cadence & Phrase
5. Unit 5 · Harmony & Voice Leading II: Chord Progressions & Predominant Function
6. Unit 6 · Harmony & Voice Leading III: Embellishments, Motives & Melodic Devices
7. Unit 7 · Harmony & Voice Leading IV: Secondary Function
8. Unit 8 · Modes and Form