How do predominant chords strengthen cadences, and how do we harmonise a melody to a cadence?
Topic 5.5 Cadences and Predominant Function: build complete cadential progressions with predominants and harmonise a given melody so it cadences correctly.
A focused answer to AP Music Theory Topic 5.5, covering full cadential progressions that include a predominant (such as I, IV or ii, V, I), how the predominant strengthens the approach to the cadence, and how to harmonise a given melody so the cadence lands correctly, with a worked harmonisation.
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What this topic is asking
The College Board (Topic 5.5) wants you to build complete cadential progressions that include a predominant (such as I to ii or IV to V to I), understand how the predominant strengthens the approach to a cadence, and harmonise a given melody so it cadences correctly.
The complete cadential progression
Inserting the predominant is what turns a minimal V to I into a satisfying, idiomatic cadence. It is the standard way to end a phrase convincingly.
Harmonising a melody to a cadence
This backward approach guarantees the cadence type you want. For a perfect authentic cadence, the final tonic must be in root position with degree 1 in the soprano, and the dominant before it must be in root position too.
Why the predominant completes the cadence
The central idea is that a strong cadence is a staged release of tension, and the predominant supplies the first stage. Starting from the tonic's rest, the predominant introduces motion toward the dominant; the dominant then builds maximum tension through its leading tone and (if a seventh) chordal seventh; and the tonic finally resolves it. Skipping the predominant shortens this arc and makes the cadence feel abrupt. When harmonising a melody, recognizing this arc lets you choose chords that produce exactly the cadence you want: place the predominant early, the dominant on the penultimate note so its leading tone can rise, and the tonic on the last. This is the practical pay-off of everything in Units 4 and 5, turning a bare melody into a fully voice-led phrase that closes correctly.
Harmonising a cadence
To harmonise a cadence, identify the final soprano notes and their scale degrees, assign predominant, dominant and tonic chords from the last note backward, voice them in SATB, and resolve the leading tone up and any chordal sevenths down, checking for parallels.
Try this
Q1. What is the full functional path of a complete cadential progression? [1 point]
- Cue. Tonic to predominant to dominant to tonic; the predominant strengthens the approach.
Q2. When harmonising a melody, why work backwards from the final note? [2 points]
- Cue. The cadence type is fixed by the last chords, so choosing the tonic, then the dominant, then the predominant guarantees the correct cadence and lets the tendency tones resolve.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2021 (style)1 marksSection I (multiple choice, written). Which progression gives the strongest, most complete approach to a perfect authentic cadence? (A) I to V to I (B) I to IV to I (C) I to ii6 to V to I (D) I to vi to IShow worked answer →
The correct answer is (C) I to ii6 to V to I.
A complete cadential progression moves tonic to predominant to dominant to tonic. Inserting a predominant (here ii6) before the dominant builds tension in stages and gives the strongest, most idiomatic approach to a perfect authentic cadence.
(A) I to V to I lacks a predominant, so the approach is shorter. (B) I to IV to I is a plagal motion, weaker than an authentic cadence. (D) I to vi to I does not reach a dominant. The trap is thinking a bare V to I is strongest; adding the predominant strengthens and completes the cadence.
AP 2023 (style)4 marksSection II (free response, harmonisation). A soprano line ends scale degree 3, 2, 1 over the final three beats of a phrase in F major. Choose chords that produce a perfect authentic cadence with a predominant, and name each chord with a Roman numeral.Show worked answer →
A 4-point harmonisation question.
(1 point) Identify the soprano: degrees 3, 2, 1 in F major are A, G, F.
(1 point) Harmonise degree 3 (A) with a predominant, for example IV (B flat, D, F) or ii6, which contains or supports A.
(1 point) Harmonise degree 2 (G) with the dominant V (C, E, G), placing the leading tone E in an inner voice and G in the soprano.
(1 point) Harmonise degree 1 (F) with the tonic I (F, A, C) in root position, soprano on F, giving a perfect authentic cadence; the full close is predominant to V to I.
Markers reward a predominant on degree 3, the dominant on degree 2 with the leading tone present, and a root-position tonic on degree 1 with the tonic in the soprano, producing a PAC.
Related dot points
- Topic 4.3 Harmonic Progression, Functional Harmony, and Cadences: explain tonic, predominant and dominant function, the normal direction of progressions, and the four cadence types.
A focused answer to AP Music Theory Topic 4.3, covering functional harmony (tonic, predominant, dominant), the normal flow tonic to predominant to dominant to tonic, and the four cadences (perfect authentic, imperfect authentic, half, plagal, with the deceptive cadence), with a worked cadence analysis.
- Topic 5.1 Adding Predominant Function IV (iv) and ii (ii diminished): use the subdominant and supertonic chords to prepare the dominant and part-write them smoothly.
A focused answer to AP Music Theory Topic 5.1, covering predominant function, the IV (iv) and ii (ii diminished) chords, how they lead to the dominant, the use of ii6 and first-inversion predominants, and smooth part-writing, with a worked predominant progression.
- Topic 5.3 Predominant Seventh Chords: use ii7 (ii diminished 7) and IV7 as predominant sevenths and resolve their chordal sevenths down by step into the dominant.
A focused answer to AP Music Theory Topic 5.3, covering the predominant sevenths ii7 (ii diminished 7 in minor) and IV7, how the chordal seventh resolves down by step into the dominant, the popular ii6/5 voicing, and smooth part-writing, with a worked resolution.
- Topic 5.6 Cadential 6/4 Chords: use the cadential six-four (I6/4 to V) and part-write its suspension-like resolution of the sixth and fourth above the bass.
A focused answer to AP Music Theory Topic 5.6, covering the cadential six-four chord (I6/4 over the dominant bass), why it behaves like a decorated dominant, the resolution of the sixth to the fifth and the fourth to the third above the bass, doubling the bass, and metrical placement, with a worked resolution.
- Topic 4.2 SATB Voice Leading: apply the rules of range, spacing, doubling, smooth motion and tendency-tone resolution when writing four-part harmony.
A focused answer to AP Music Theory Topic 4.2, covering the four-voice ranges, the spacing rule (no more than an octave between adjacent upper voices), doubling guidelines, the ban on parallels and voice crossing, and resolving the leading tone and tendency tones, with a worked voicing.
Sources & how we know this
- AP Music Theory Course and Exam Description — College Board (2024)