Cadences and Musical Punctuation

Introduction: The Musical Sentence

Imagine reading a novel with no periods commas or question marks the words just keep running together without a break until the reader is exhausted and confused.

Music needs punctuation too. A melody is a musical sentence, and a cadence is its punctuation mark: a chord progression that gives a sense of temporary or final closure, letting the music breathe. Cadences are the structural pillars of a phrase, so when you analyze or write music, find the cadences first.

Click any example to hear it.

Authentic Cadences: The Period

An authentic cadence is dominant to tonic: V (or V⁷) → I. It comes in two strengths.

Perfect authentic cadence (PAC): the strongest and most final cadence. All three conditions must be true:

1. V (or V⁷) moves to I,
2. both chords are in root position, and
3. the soprano ends on the tonic (1̂).

Imperfect authentic cadence (IAC): any authentic cadence that misses one of those conditions. It still closes, but less finally:

• the soprano ends on 3̂ or 5̂ instead of 1̂ (the most common kind),
• either chord is inverted (V⁶–I, V⁷–I⁶), or
• vii°⁶ replaces V.

The cadential six-four from Chapter 8B often decorates an authentic cadence: ii⁶–I⁶₄–V⁷–I.

The Half Cadence: The Comma

A half cadence (HC) ends on V. Any chord can lead into it (most often I, IV, ii, or a cadential six-four), and it leaves the listener hanging on the dominant's tension: a comma or a question mark, demanding that the music continue.

In minor, a special half cadence moves from iv⁶ to V: the bass falls by half step (6̂–5̂), recalling the Phrygian mode. It's called the Phrygian half cadence, and it's a favorite way to end a slow movement in Baroque music before the next movement begins.

The Plagal Cadence: The Amen

A plagal cadence (PC) is IV → I (iv → i in minor). It's the "Amen" at the end of hymns, and it usually comes after an authentic cadence has already closed the piece, as an epilogue rather than the main punctuation.

The Deceptive Cadence: The Plot Twist

A deceptive cadence (DC) builds up the tension of V, so the listener expects I, then swerves to vi (VI in minor). The bass rises a step instead of falling a fifth. Because the leading tone must still rise to the tonic, double the third of vi (which is the tonic note).

A deceptive cadence usually isn't the end. It extends the phrase, which then heads back toward a true authentic cadence.

Summary

Try It: Cadence Lab

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