Level 2 · Course 24

Les accords de sixte augmentée

It+6, Fr+6, Ger+6 — three Romantic altered chords, their contrary-motion resolution, and their use in 19th-century music.

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Pause Culture · Expressive altered chords

Franz Liszt (1811–1886)

Liszt used the German augmented sixth as his harmonic signature — a chord that concentrates all romantic tension in 3 or 4 notes.

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À retenir : One well-placed altered chord is worth ten ordinary ones.

The three augmented sixths

The augmented sixth chord is an altered pre-dominant chord characterized by the augmented sixth interval between bVI (in the bass) and #IV. Three variants exist — Italian, French and German — each with its own construction and color.

Context in C major: In all the examples below, we are in C major. bVI = Ab, I = C, #IV = F#. These three notes form the common core of all augmented sixth chords.

Click a chord to expand it and listen.

It+6

Italian sixthbVI – I – #IV

The simplest of the three

Lab – Do – Fa#

Fr+6

French sixthbVI – I – II – #IV

Contains the dominant ninth (D). More colorful than the Italian, it already hints at the sound of V9.

Lab – Do – Ré – Fa#

Al+6

German sixthbVI – I – bIII – #IV

The richest and most commonly used. Enharmonically identical to a dominant seventh chord (Ab7), but its resolution is different.

Lab – Do – Mib – Fa#

Universal rule of augmented sixths: Regardless of type (It+6, Fr+6, Al+6), the augmented sixth interval (bVI–#IV) always resolves by contrary motion to the dominant fifth. In C major: Ab moves down to G, F# moves up to G. This convergence is mandatory.