Harmony
Augmented Sixth Chords: Italian, French and German Types
Italian, French and German sixth chords: how each type is built, how they resolve to V, and their use in enharmonic modulation.
Augmented sixth chord
A chord built on the lowered sixth and raised fourth scale degrees, which resolve outward by step to the octave on the dominant.
Also called: Augmented sixth, Italian sixth, French sixth, German sixth
An augmented sixth chord contains an augmented sixth, the interval between the lowered sixth scale degree and the raised fourth. In A minor these are F and D♯, a span of ten semitones. Both notes move by step: D♯ rises to E and F falls to E, which sounds as an octave on the dominant. Three forms are named by the notes added to the basic pair. The Italian sixth contains only the lowered sixth, the tonic and the raised fourth, so in A minor it is F, A and D♯. The French sixth adds the supertonic, giving F, A, B and D♯. The German sixth adds the lowered third as well, giving F, A, C and D♯. All three are predominants, and they usually lead to the dominant.
Related terms
- Neapolitan chordA major triad on the lowered second scale degree, usually in first inversion as ♭II6, which typically moves to the dominant.
- Dominant seventh chordA major triad with a minor seventh above the root, such as G B D F. Its tritone pulls strongly toward the tonic.
- ChromaticismThe use of pitches outside the key's diatonic scale, such as accidentals and chromatic chords, for colour and tension.
- Functional harmonyA system in which each chord in a key has a role: tonic for rest, dominant for tension, and predominant for preparation.