What is a cadence, and why every phrase has one

A phrase is a self-contained musical thought, usually four or eight bars. Every phrase has to land somewhere. The chord it lands on, and the chord that brought it there, are the cadence. Learn to hear four of them and most tonal music becomes legible.

Authentic cadence (V to I)

The default full stop. In C major, that is G resolving to C. A perfect authentic cadence puts both chords in root position with the tonic in the top voice. An imperfect authentic cadence relaxes one of those conditions. Listen for it at the end of most hymns and most 18th-century phrases.

Half cadence (any chord to V)

A comma, not a full stop. The phrase ends on the dominant, leaving the ear waiting. In C major, most half cadences land on G. The opening phrase of Mozart’s Eine kleine Nachtmusik is textbook half-cadence.

Plagal cadence (IV to I)

The ‘Amen’ cadence. In C major, F to C. Softer than the authentic cadence because the leading tone (B) is not present in the IV chord. Common in hymns and in the fade-out of pop ballads.

Deceptive cadence (V to vi)

The dominant sets up the tonic, then swerves. In C major, G resolves to A minor instead of C. The ear feels unfinished; the composer uses the extra time to write another phrase. Listen for it in Bach chorales and in Radiohead.

Hear them in the tool

Open the chord progression generator in C major. Play I-IV-V-I to hear an authentic cadence. Play I-IV-V and stop; that is a half cadence. Play I-IV-I; that is plagal. Play I-V-vi; that is deceptive.