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Unit 4 · Harmony & Voice Leading I Flashcards Cheat Sheet Essentials Visual Review MC Practice FRQ Practice

AP Music Theory Unit 4 Essentials

The must-know terms and core concepts for Unit 4: Chord Function, Cadence, and Phrase. Every vocabulary word and idea you need to master.

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Key Concept 1
Chords have function within a key
Beyond their spelling, chords play roles. Tonic chords (I, vi) feel like home; predominant chords (ii, IV) build momentum; dominant chords (V, vii°) create tension that resolves back to tonic. Harmony tends to move in the cycle tonic → predominant → dominant → tonic, which is why some progressions sound satisfying and others sound aimless.
Tonic Predominant Dominant
Key Concept 2
Cadences and phrases are music's grammar
A phrase is a musical sentence, and a cadence is its punctuation. A PAC is a firm period; a half cadence is a comma that leaves you hanging; a deceptive cadence is a surprise. Two phrases often pair into a period — an antecedent that asks a question (weak cadence) and a consequent that answers it (strong cadence).
Cadences Phrase Period
Key Concept 3
Voice leading connects chords smoothly
In four-part (SATB) writing, each chord must connect to the next with independent, singable lines. Keep common tones, move the other voices by the smallest step, and favor contrary motion. The cardinal sins are parallel fifths and octaves, which make two voices lose their independence. Correct doubling (usually the root) and spacing keep the texture clear.
SATB Parallels Motion
Key Concept 4
Tendency tones must resolve
Certain pitches carry a built-in pull. The leading tone (scale degree 7) resolves up a half step to the tonic; the chordal seventh of any seventh chord resolves down by step. These resolutions are exactly what gives a V7 → I its powerful sense of arrival, and honoring them is the key to clean part-writing.
Leading Tone Chordal Seventh V7 Resolution
Harmonic function
A chord's role in a key: tonic (stability), predominant (motion), or dominant (tension seeking resolution).
Function & Cadence
Tonic function
The "home" role, provided by I (and often vi). Progressions begin and usually end here.
Function & Cadence
Predominant function
Chords (ii, IV) that lead into and set up the dominant.
Function & Cadence
Dominant function
Chords (V, vii°) that create tension and pull strongly back to tonic.
Function & Cadence
Cadence
A harmonic and melodic formula that ends a phrase, acting like punctuation.
Function & Cadence
Authentic cadence (PAC / IAC)
A V–I cadence. Perfect (PAC): both chords in root position with tonic in the soprano. Imperfect (IAC): missing one of those conditions.
Function & Cadence
Half cadence (HC)
A phrase ending on the dominant (V); it sounds unresolved.
Function & Cadence
Plagal cadence
A IV–I cadence, often called the "Amen" cadence.
Function & Cadence
Deceptive cadence
A cadence where V resolves to vi instead of I, thwarting the expected tonic.
Function & Cadence
Phrase
A complete musical unit that ends with a cadence — a musical "sentence."
Phrase & Form
Period
Two phrases working together: an antecedent (weaker cadence) followed by a consequent (stronger cadence).
Phrase & Form
Antecedent & consequent
The "question" phrase (often ending in a half cadence) and the "answer" phrase (often ending in a PAC).
Phrase & Form
SATB
The four-voice texture of soprano, alto, tenor, and bass used for part-writing.
Voice Leading
Parallel fifths / octaves
Two voices moving in the same direction while keeping a perfect 5th or octave — forbidden in this style because it destroys voice independence.
Voice Leading
Types of motion
Parallel (same direction, same interval), similar (same direction, different interval), oblique (one voice holds), and contrary (opposite directions).
Voice Leading
Voice crossing & overlap
Errors where a lower voice moves above a higher one (crossing) or past where an adjacent voice just was (overlap). Both are avoided.
Voice Leading
Doubling
Which chord tone appears in two voices. Usually the root of a root-position triad; never the leading tone.
Voice Leading
Spacing
The distance between voices. Keep no more than an octave between adjacent upper voices (S–A and A–T).
Voice Leading
Tendency tones
Notes that must resolve: the leading tone rises a half step to the tonic; the chordal seventh falls by step.
Voice Leading
V7 resolution
In V7 → I, the leading tone rises to tonic, the seventh falls to the third of I, and the fifth is often omitted so I is complete.
Voice Leading