What Are Italian, French and German Augmented-Sixth Chords, and How Do They Resolve to the Dominant?

Augmented-Sixth Chords: How Chromatic Harmony Intensifies the Dominant

Among the most distinctive chromatic harmonies in tonal music are the augmented-sixth chords.

They are particularly effective before cadences because they create a strong tendency towards the dominant. Their characteristic interval — an augmented sixth — expands outward to an octave as the music approaches the dominant bass note.

Unlike an ordinary dominant chord, an augmented-sixth chord functions primarily as a predominant harmony. It prepares the dominant and makes its arrival more dramatic.

The three traditional types are the Italian, French and German augmented-sixth chords.

1. What Is an Augmented-Sixth Chord?

An augmented sixth is an interval consisting of eight semitones when measured between the appropriately spelled notes.

In C minor, the characteristic notes are:

• A-flat, the lowered sixth scale degree
• F-sharp, the raised fourth scale degree

The interval between A-flat and F-sharp is an augmented sixth.

The two notes have a strong tendency to move outward:

• A-flat moves down to G.
• F-sharp moves up to G.

Both voices therefore converge on the dominant pitch G, producing an octave.

This characteristic outward resolution gives the augmented-sixth chord its name and its distinctive harmonic function.

2. Why the Augmented Sixth Is Important

The two chromatic notes create an unusually strong approach to the dominant.

In C minor, G is the dominant scale degree.

A-flat lies one semitone above G, while F-sharp lies one semitone below it.

Their opposing movements converge on G.

This creates a powerful sense of harmonic direction.

The chord does not simply introduce chromatic colour. Its two defining notes are arranged to lead directly towards the dominant.

This is why augmented-sixth chords are commonly used immediately before dominant harmony in cadential progressions.

3. The Italian Augmented-Sixth Chord

The Italian augmented-sixth chord is the simplest of the three traditional types.

In C minor, its notes are:

A-flat – C – F-sharp

The chord contains three distinct pitch classes, with C typically doubled in four-part writing.

Its characteristic interval is formed by A-flat and F-sharp.

A typical progression is:

Italian +6 → V → i

In C minor:

A-flat–C–F-sharp → G–B–D → C–E-flat–G

The outer voices move towards G, while the remaining voice or voices connect to suitable tones of the dominant chord.

The Italian augmented sixth is relatively compact and can create a direct, concentrated approach to the dominant.

4. The French Augmented-Sixth Chord

The French augmented-sixth chord adds a fourth note.

In C minor, its notes are:

A-flat – C – D – F-sharp

The D creates a characteristic whole-tone relationship with A-flat and F-sharp within the chord's structure.

The French augmented sixth is often described as having a more distinctive or less conventionally triadic sound than the Italian version.

Its additional note creates further voice-leading possibilities.

The characteristic A-flat and F-sharp still resolve outward to G, preparing the dominant.

5. The German Augmented-Sixth Chord

The German augmented-sixth chord also contains four notes.

In C minor, its notes are:

A-flat – C – E-flat – F-sharp

It resembles a dominant seventh chord in sound when enharmonically reinterpreted, but its theoretical spelling and voice-leading function are different.

The interval A-flat–F-sharp is the augmented sixth.

The chord typically resolves towards the dominant, with the outer notes moving outward to G.

A traditional German augmented-sixth chord can produce parallel fifths if it moves directly to a root-position dominant in a straightforward four-part arrangement. Composers often avoid this by inserting a cadential 6/4 chord or by using an alternative voice-leading arrangement.

This is an important distinction: the German augmented-sixth chord has a characteristic sound, but its resolution requires attention to contrapuntal detail.

6. Comparing the Three Types

All three chords contain the characteristic augmented sixth, but they differ in their internal structure.

Their common function is to prepare the dominant.

The difference lies in the additional notes and the voice-leading possibilities they create.

7. Resolving Augmented-Sixth Chords

The most important voice-leading event is the outward resolution of the augmented sixth.

In C minor:

A-flat → G

F-sharp → G

The two notes converge on the dominant root.

The remaining chord tones also move into the dominant harmony.

For example, the French augmented-sixth chord:

A-flat – C – D – F-sharp

can resolve towards a G major dominant chord:

G – B – D

The exact distribution between voices depends on the arrangement.

In traditional tonal harmony, the augmented-sixth chord is generally understood as a predominant sonority. Its characteristic resolution prepares the dominant, which then usually proceeds to the tonic.

8. Augmented-Sixth Chords and the Cadential 6/4

Augmented-sixth chords can be combined with a cadential 6/4 to create an elaborate dominant preparation.

A possible progression in C minor is:

German +6 → cadential 6/4 → V → i

The cadential 6/4 places the tonic triad over the dominant bass and resolves into the dominant harmony.

This creates several stages of preparation before the final tonic arrival.

The augmented-sixth chord establishes the chromatic pull towards the dominant. The cadential 6/4 further intensifies the dominant preparation, and the dominant then resolves to the tonic.

The result can be particularly effective at the end of a large musical section.

9. Augmented-Sixth Chords in Classical and Romantic Music

Augmented-sixth chords are strongly associated with the tonal language of the Classical and Romantic periods.

They appear in orchestral, operatic and instrumental music, where they can create dramatic harmonic preparation.

Romantic composers explored their possibilities extensively, using them in increasingly chromatic contexts and sometimes connecting them with enharmonic reinterpretation and modulation.

Their expressive power comes from the combination of chromatic colour and clearly directed voice leading.

10. Augmented-Sixth Chords in Electronic Music

The augmented-sixth interval offers electronic composers an interesting way to create tension between two independent pitch layers.

In C minor, one synthesizer voice can sustain A-flat while another plays F-sharp.

The two pitches create the characteristic augmented-sixth relationship.

When both move towards G, the tension resolves into a unison or octave relationship, depending on their registers.

This can be implemented with:

• Two independent MIDI or CV-controlled oscillators
• A sustained pad and a moving melodic voice
• Separate sequencers generating the two chromatic pitches
• A generative system that delays the outward resolution
• A layered texture in which the two pitches converge gradually

The result need not sound like a conventional orchestral chord. The interval can be distributed across registers, timbres and rhythmic layers.

The essential relationship remains: two pitches move in opposite directions towards the dominant.

11. Practical Exercise

Work in C minor.

First, play a simple progression:

Cm – Fm – G7 – Cm

Now replace the F minor predominant with three different augmented-sixth chords.

Version A: Italian augmented sixth

A-flat – C – F-sharp

Version B: French augmented sixth

A-flat – C – D – F-sharp

Version C: German augmented sixth

A-flat – C – E-flat – F-sharp

Resolve each chord towards G7 and then C minor.

Listen to the differences in colour and tension.

Pay particular attention to the outward movement:

A-flat → G

F-sharp → G

Finally, try inserting a cadential 6/4 between the augmented-sixth chord and the dominant.

Notice how the additional preparation changes the weight of the final cadence.

Conclusion

Augmented-sixth chords are among the most distinctive tools in chromatic tonal harmony.

Their characteristic interval creates an outward movement towards the dominant, making them particularly effective before important cadences.

The Italian, French and German forms provide different harmonic colours while sharing the same basic predominant function.

For composers, they demonstrate how two carefully chosen chromatic notes can create a powerful sense of direction.

The chord's effect is not simply the result of unusual pitches. It comes from the way those pitches are expected to move.

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