Lessons · Intermediate
Cadences in Music: Authentic, Plagal, Half and Deceptive
How phrases end: the six cadences every musician should recognize, play and write.
What is a cadence?
A cadence is a pair of chords that ends a musical phrase. Just as punctuation tells a reader where a sentence stops, a cadence tells the listener whether the music has finished (a full stop), is only pausing (a comma), or has taken a surprising turn (a question mark).
Cadences are built from the chords of a key, so you need to know diatonic harmony first: in C major the chords are C, Dm, Em, F, G, Am and B°, numbered I ii iii IV V vi vii°. Every cadence below is described with these Roman numerals, which means it works in any key.
There are two big families:
- Closed cadences end on the tonic chord (I or i). They sound finished.
- Open cadences end on a chord other than the tonic, most often V. They sound unfinished and ask for more music.
Authentic cadence (V–I)
The authentic cadence moves from the dominant (V or V7) to the tonic (I). It is the strongest ending in tonal music because two things happen at once:
- the bass falls a fifth (or rises a fourth) from the 5th degree to the 1st;
- the leading tone (the 7th degree, B in C major) rises a half step to the tonic.
If you use V7, the 7th of the chord (F in G7) also falls a half step to the 3rd of the tonic (E). Those two half-step resolutions, B to C and F to E, resolve the tritone inside G7, and that is why the ending feels so final.
Perfect authentic cadence (PAC)
An authentic cadence is called perfect when all three conditions are met:
- both chords are in root position (G in the bass, then C in the bass);
- the progression is V(7)–I, not vii°–I;
- the highest note of the final chord is the tonic (C).
This is the "full stop" that closes most pieces and most sections.
Imperfect authentic cadence (IAC)
If any of those conditions is missing, the cadence is imperfect: still V–I, still closed, but slightly weaker. Typical cases are a final chord with E or G on top, or a dominant in inversion (G/B going to C). Composers use the IAC to end a phrase in the middle of a piece and keep the PAC for the real ending.
Plagal cadence (IV–I)
The plagal cadence moves from the subdominant (IV) to the tonic (I): F to C in C major. It is softer than the authentic cadence because there is no leading tone; the common tone C stays put while the other voices slide down by step (A to G, F to E).
It is often heard after an authentic cadence as an extra, gentle confirmation of the ending, and it is the typical "amen" ending of hymns. In minor keys it becomes iv–i (Dm to Am in A minor), which sounds darker. A popular variant in major keys borrows the minor iv: Fm to C, a warm, slightly melancholy close.
Half cadence (ends on V)
A half cadence is any phrase that stops on the dominant chord. The chord before V can be almost anything: I–V, ii–V, IV–V, or vi–V. In C major, a phrase ending on G sounds like a comma: the listener expects the next phrase to continue and eventually resolve to C.
Half cadences are the classic way to end the first half of a "question and answer" pair of phrases. The first phrase ends on V (question), the second phrase ends with a perfect authentic cadence (answer).
Deceptive cadence (V–vi)
The deceptive cadence (also called interrupted cadence) sets up an authentic cadence and then swaps the expected tonic for the vi chord: G to Am in C major. The leading tone B still rises to C, and Am shares two notes (C and E) with the C chord, so the move sounds logical but surprising.
Its job is to postpone the ending. A phrase that ends deceptively usually repeats or extends until it finally reaches a real authentic cadence.
Cadences in A minor
In minor keys the dominant chord must be major to create a leading tone. The natural minor scale of A has G natural, which is a whole step below A and does not pull strongly upward. The harmonic minor scale raises it to G#, turning Em into E (or E7). That is why minor-key cadences almost always use a major V. See minor scales for the full story.
| Cadence | Formula | A minor | Feeling |
|---|---|---|---|
| Authentic | V(7)–i | E7 – Am | final, closed |
| Plagal | iv–i | Dm – Am | soft, dark close |
| Half | any – V | Dm – E | open, suspended |
| Deceptive | V–VI | E – F | surprise, delay |
| Phrygian half | iv6–V | Dm/F – E | open, solemn |
Notice the deceptive cadence in minor goes to the major VI chord (F), not to a minor chord. The leading tone G# rises to A, which is the 3rd of F major.
The Phrygian half cadence (iv6–V)
The Phrygian half cadence is a special half cadence found only in minor keys. It goes from the iv chord in first inversion to V: Dm/F to E in A minor. Its signature is in the outer voices:
- the bass falls a half step, F to E (the same half step that opens the Phrygian mode, hence the name);
- the top voice rises a whole step, D to E, so the outer voices expand from a sixth to an octave.
It sounds solemn and slightly archaic, and Baroque composers often used it at the end of a slow movement that leads directly into a fast one. On guitar you can hear it clearly with this voicing: Dm/F with the F on the low E string, then an open E chord.
Cadences in C major: summary
| Cadence | Formula | C major | Closed or open |
|---|---|---|---|
| Perfect authentic | V(7)–I, root position, tonic on top | G7 – C | closed, strongest |
| Imperfect authentic | V–I with inversion or 3rd/5th on top | G/B – C | closed, weaker |
| Plagal | IV–I | F – C | closed, soft |
| Half | any – V | F – G | open |
| Deceptive | V–vi | G – Am | open, surprising |
How to recognize cadences by ear
Start by listening only to the last two chords of each phrase and ask one question: does it sound finished?
- If yes and it feels strong and decisive, it is almost certainly authentic.
- If yes but gentle, with no strong pull, think plagal.
- If no and the music feels like it is holding its breath, it is a half cadence.
- If you were expecting a full stop and got a "minor-sounding" surprise instead, it is deceptive.
Singing the bass line helps a lot: a bass that falls a fifth (or rises a fourth) to the tonic signals an authentic cadence; a bass that rises one step from 5 to 6 signals a deceptive cadence.
Practice
- Play every cadence in the C major table on guitar or piano, then repeat in A minor. Say the name out loud as you play.
- Transpose the five cadences to G major (D7–G, C–G, C–D, D–Em) and to E minor (B7–Em, Am–Em, Am–B, B–C). Check your answers with the transposer.
- Use the progression player to play I–IV–V–I, I–IV–V–vi and I–ii–V in random keys and name the cadence at the end of each.
- Write an eight-bar melody on staff paper: bars 1–4 end with a half cadence, bars 5–8 with a perfect authentic cadence.
- Train your ear for chord qualities with the ear trainer, so the difference between V–I and V–vi becomes instant.
Related lessons: diatonic harmony, chord progressions, seventh chords, chord inversions and minor scales. Spell the chords involved with the triads worksheet and seventh chords worksheet.