A one-page visual summary of Chord Function, Cadence, and Phrase — harmonic function, the cadence types, phrase structure, and the SATB voice-leading rules, on a single screen.
What it covers: How harmony works and how to write it in four voices — harmonic function, cadences, phrase structure, SATB voice-leading rules, and resolving seventh chords.
Exam weight: AP Music Theory is weighted by section, not by unit (45% multiple choice, 45% free response, 10% sight-singing). Units 4–7 (harmony and voice leading) dominate the free-response part-writing and analysis.
The big question: How do chords function within a key to create tension and resolution, and how do you connect them smoothly in four voices?
Big Ideas covered: Pitch (BI 1), Form (BI 3), Music Design (BI 4).
Key topics at a glance
Harmonic Function
Tonic (I, vi) = home. Predominant (ii, IV) = sets up the dominant. Dominant (V, vii°) = tension that resolves to tonic. Cycle: T → PD → D → T.
The Cadences
PAC / IAC = V–I. HC ends on V. Plagal = IV–I. Deceptive = V–vi. PAC is the strongest ending; HC sounds unfinished.
Phrases & Periods
A phrase ends with a cadence. A period pairs an antecedent (weaker cadence, often HC) with a consequent (stronger, often PAC).
The Four Voices (SATB)
Soprano, Alto, Tenor, Bass, high to low. Soprano and bass are the outer voices. Usually double the root of a root-position triad.
Voice-Leading Don'ts
No parallel fifths or octaves. Avoid voice crossing and overlap. Don't double the leading tone (it must resolve up).
Types of Motion
Contrary (opposite), oblique (one holds), similar (same direction), parallel (same interval). Contrary motion is safest.
Tendency Tones
The leading tone (7) resolves up to tonic; the chordal seventh resolves down by step. These drive V(7) → I.
Resolving V7
Leading tone → tonic; seventh → down a step to the 3rd of I; the fifth is often omitted (root doubled) so I is complete.
The key terms you must know
Harmonic function — a chord's role: tonic (T), predominant (PD), or dominant (D).
Cadence — the harmonic formula that ends a phrase, like punctuation.
PAC vs. IAC — authentic cadences (V–I); PAC has both chords in root position with tonic in the soprano, IAC does not.
Half cadence — a phrase ending on V; sounds unfinished.
Plagal cadence — IV–I, the "Amen" cadence.
Deceptive cadence — V–vi instead of V–I.
Phrase & period — a unit ending in a cadence; a period is antecedent + consequent phrases.
SATB — the four voices: soprano, alto, tenor, bass.
Parallel fifths / octaves — forbidden similar motion keeping a P5 or P8 between two voices.
Types of motion — parallel, similar, oblique, contrary.
Tendency tone — a note that must resolve: leading tone up to tonic, chordal seventh down by step.
Doubling & spacing — usually double the root; keep ≤ an octave between adjacent upper voices.
Key themes to remember
Harmony moves in functions. Think T → PD → D → T, not just chord-by-chord — function explains why progressions work.
Cadences are punctuation. The cadence type tells you how strongly a phrase closes (PAC = period, HC = comma).
Smooth is the goal. Keep common tones, move other voices by step, and use contrary motion to avoid parallels.
Tendency tones aren't optional. The leading tone rises to tonic and the chordal seventh falls by step — every time.
Write for four independent voices. Correct doubling, spacing, and motion keep the parts sounding independent.
Common exam traps
Parallel fifths and octaves are the classic point-losers. Check every pair of voices — especially the outer voices — for parallel P5s and P8s.
PAC has strict requirements. If either chord is inverted, or the soprano doesn't end on the tonic, it's an IAC, not a PAC.
A half cadence ends ON V. It is not "V–I ending on V" — the phrase simply stops on the dominant.
Don't double the leading tone. Doubling scale degree 7 forces parallel octaves when both resolve up to tonic.
Resolve the seventh down. The chordal seventh always steps down; letting it leap or rise is a common voice-leading error.
Deceptive ≠ plagal. Deceptive is V–vi; plagal is IV–I. Both avoid a straightforward V–I, but they're different chords.