Cadences

A cadence is a harmonic gesture that ends a musical phrase, the way a comma or full stop ends a sentence. The strength of a cadence determines whether the phrase feels closed (a definite ending) or open (a continuation expected). Cadences are the punctuation of tonal music, and their handling is one of the things separating skilled composers from beginners. A piece without varied cadences is a piece without breath.

There are four canonical cadence types in Western harmony — perfect authentic, imperfect authentic, plagal, and half — plus a fifth that subverts expectation, the deceptive cadence. Each has a characteristic chord progression and a characteristic effect on the listener. Once the ear knows the four cadences it can predict where a phrase will end, often before the bar line confirms it.

The perfect authentic cadence (PAC) moves V to I with both chords in root position and the soprano landing on the tonic. It is the strongest possible ending in tonal music, the equivalent of a full stop. Almost every classical movement closes on a PAC, and many phrases within the movement do too. When a PAC arrives the listener feels the music has finished; the next note has the weight of a fresh start.

Soprano:  D — C
Alto:     B — C
Tenor:    G — G
Bass:     G — C
Chord:    V → I

The imperfect authentic cadence (IAC) is also V to I, but with at least one of the conditions for the PAC weakened: an inversion, the soprano landing on the third or fifth of the tonic chord, or a substitute for V (such as vii° resolving to I). The IAC still ends a phrase but with less finality — more like a strong comma than a full stop. Bach uses imperfect authentic cadences inside long fugue subjects to keep the energy moving forward without releasing it entirely.

The plagal cadence moves IV to I. It has a softer, more contemplative quality than the authentic cadence and is sometimes called the amen cadence because it ends so many hymns. Its lack of leading-tone resolution makes it less assertive but no less final when used at the end of a piece. Mendelssohn, Brahms, and many Anglican hymn writers reach for the plagal cadence whenever a piece needs to close gently rather than emphatically.

• Authentic cadence: V → I — full stop.
• Plagal cadence: IV → I — soft full stop.
• Half cadence: any → V — comma.
• Deceptive cadence: V → vi — surprise.

The half cadence ends on V rather than I. It produces an open, unfinished feeling — a comma rather than a full stop — and is used to close the antecedent phrase of a parallel period, leaving room for the consequent phrase to answer. Without the half cadence, the long-breath musical paragraph of Classical-period music would not exist. Mozart uses half cadences as breathing points in operatic recitative, in symphonic exposition, and in the slow movements of his concertos.

The Phrygian half cadence is a special variant in minor keys: iv6 to V. The bass moves from F-natural to G in A minor, and the upper voices outline a Phrygian melodic descent. Bach used it constantly to close minor-key movements that were going to continue into the next movement of a suite or sonata. The mood is grave but unfinished — the perfect setup for what comes next.

The deceptive cadence sets up a perfect authentic cadence — V dominant chord ringing out, expectation primed — and then resolves to vi (the relative minor) instead of I. The effect is exactly what the name suggests: a small, controlled disappointment, used to extend a phrase past its expected ending and prepare a stronger final cadence to come. The listener hears the V, leans into the expected resolution, and is gently redirected.

Other deceptive resolutions are possible — V to IV, V to V/IV, V to a chromatic chord — but the V to vi resolution is by far the most common. Listen for it in the codas of Beethoven sonatas and in the climactic passages of Wagner: the dominant lifts, the bass drops to vi instead of I, and the music continues for another phrase or section before finding its true close. A coda that does not deceive at least once is a coda that ends too soon.

In a four-bar phrase the cadence usually falls on the fourth bar. In an eight-bar period the antecedent (bars 1-4) typically ends on a half cadence, and the consequent (bars 5-8) ends on an authentic cadence. The combination of a question and an answer is what makes the period feel balanced. Mozart's piano sonatas and Beethoven's early string quartets are textbooks of this form; the cadences are how the form is felt rather than analysed.

In jazz, the ii-V-I is the cadence to learn first. The ii is a pre-dominant — usually a minor seventh — that prepares the V dominant seventh, which then resolves to the I major seventh. The whole cadence is three anti-clockwise steps around the cycle of fifths. Blowing changes through ii-V-I in every key is the foundation of jazz improvisation; without it, the harmonic vocabulary stays superficial.

Cadences are the easiest harmonic gesture to hear because the bass moves predictably and the soprano line resolves audibly. Train your ear by listening for the fall of a fifth in the bass at every phrase ending — that is the signature of an authentic cadence. Listen for the rise of a fourth in the bass — that is the signature of a plagal cadence.

Listen for a chord that simply hangs unresolved — that is the half cadence. Once these three patterns are reflexive, your sense of musical phrasing will be permanently altered.