Theory & harmony
Cadence
A cadence is the harmonic formula that ends a musical phrase, functioning like punctuation to signal a full stop, a comma, or a surprise.
The four standard types are the authentic cadence, dominant to tonic, which sounds conclusive; the plagal cadence, subdominant to tonic, the "amen" ending; the half cadence, which stops on the dominant and sounds unfinished; and the deceptive cadence, where the dominant resolves somewhere other than the tonic, usually the submediant.
Recognising cadences is what turns a page of notes into phrases, and phrases are what a listener actually hears. For a performer this is directly practical: knowing where a phrase closes tells you where to relax the bow, where to breathe with the ensemble, and where not to.
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Identify the chords at a phrase ending
In C major, chord I is C–E–G, chord IV is F–A–C, chord V is G–B–D and chord vi is A–C–E. Roman numerals name each chord by its scale degree.
V → I: G major → C major IV → I: F major → C major V → vi: G major → A minor
At phrase endings, V–I is called perfect in common British exam terminology, or authentic in American terminology. IV–I is plagal. V–vi is interrupted (deceptive). An ending on V is imperfect (half). In American theory, a perfect authentic cadence has additional bass and melody requirements; a chord pair alone does not establish those.
Check your understanding
A phrase in C major ends with G–B–D followed by A–C–E. Which cadence does this chord progression suggest?
Show answer and explanation
An interrupted, or deceptive, cadence: V moves to vi instead of the expected tonic chord I. The final A minor chord is vi in C major, not a change to an A minor key by itself.
A common mix-up
Two adjacent chords are not automatically a cadence: their place at a phrase ending matters. Use the key and all chord tones rather than only the final melody note to identify the harmony.
Related terms
Every term in this glossary is taught in context somewhere in Arco's curricula, on the staff, on the keyboard, and on your own fingerboard at the same time.