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Cadential formulas are standardized harmonic patterns that close or punctuate phrases, signaling different degrees of finality. The authentic cadence (V–I) provides strong closure, the plagal cadence (IV–I) sounds traditional and stable, and the half cadence (I–V or IV–V) creates open continuity. Mastering these formulas allows composers to shape listener expectation clearly and give structural articulation to extended pieces.
Study how classical composers use different cadences to shape phrases. Compose short phrases, each ending with a different cadence, and listen to how each signals finality or continuation.
Only authentic cadences sound conclusive; each cadence type has legitimate structural function. The choice depends on context and the degree of closure desired.
A cadence is to musical phrases what punctuation is to sentences — it tells the listener whether a thought is complete, continuing, or questioning. You already know the underlying harmonic vocabulary from your work with harmonic function: tonic (I) provides stability, dominant (V) creates tension, and subdominant (IV) prepares motion. Cadential formulas crystallize those functional relationships into specific, recognizable endings that composers have used for centuries to organize phrase structure.
The authentic cadence (V–I) is the musical equivalent of a period. The dominant chord builds tension through its unstable tendency tones, and the resolution to tonic provides a satisfying sense of arrival. A perfect authentic cadence (PAC) — where both chords are in root position and the soprano ends on the tonic — is the strongest possible closure. If either chord is inverted or the soprano ends on a chord tone other than tonic, it becomes an imperfect authentic cadence (IAC), which closes but with slightly less finality. The half cadence (ending on V) functions like a comma or semicolon — it pauses the phrase on an unstable harmony, creating anticipation for what follows. The plagal cadence (IV–I) provides closure without the sharp tension-release of V–I; its mellow "amen" quality makes it common in sacred music and as an afterthought following an authentic cadence.
When composing, cadence choice is a structural decision. A period (antecedent + consequent phrase pair) typically ends its antecedent phrase with a half cadence — creating an open question — and its consequent with a perfect authentic cadence that answers it decisively. The deceptive cadence (V–vi) allows composers to avoid expected closure: the ear prepares for tonic arrival and lands somewhere unexpected, extending the phrase or redirecting its momentum. Used well, the deceptive cadence is a powerful surprise; used carelessly, it simply sounds like a mistake.
Mastering cadential formulas is ultimately about controlling the listener's sense of arrival and continuation. Strong closure (PAC) terminates a thought; weak closure (IAC, plagal) creates a sense of conclusion that still invites continuation; open endings (half cadence) keep the forward momentum alive. As you compose, think of cadences as the primary tools for shaping the formal arc — the moments of punctuation that make a longer piece legible to the listener.
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