V. Chromaticism
Augmented Sixth Chords
Brian Jarvis
Key Takeaways
- Augmented sixth chords are a group of chromatic predominant chords containing the interval of an augmented sixth between le and fi [latex](\downarrow\hat6-\uparrow\hat4)[/latex].
- There are Italian (It+6), French (Fr+6), and German (Ger+6) augmented sixth chords.
- Augmented sixth chords have no root, and they resolve to a root-position dominant chord.
Brief Overview
Augmented sixth chords are a category of chromatic predominant harmonies whose name is derived from the inclusion of a very specific interval: the augmented sixth between le and fi [latex](\downarrow\hat6–\uparrow\hat4)[/latex]. Each augmented sixth chord (Italian, French, and German) contains one or two other scale degrees in addition to this interval, as summarized in the chart below and illustrated in . Augmented sixth chords can occur in both major and minor keys, but they’re more common in minor.
| +6 Type | Scale Degrees | Solfege |
|---|---|---|
| Italian | [latex]\hat{1}[/latex] | do |
| French | [latex]\mathrm{\hat1\ and\ \hat2}[/latex] | do & re |
| German | [latex]\mathrm{\hat1\ and\ \downarrow\hat3\ (or\ \hat1\ and\ \uparrow\hat2)}[/latex] | do & me (or do & ri) |
Context
You’re now familiar with the process of finding a chord’s root for Roman numeral analysis, but augmented sixth chords are not typically categorized by root. Instead, they are identified as chords containing the augmented sixth between le and fi [latex](\downarrow\hat6–\uparrow\hat4)[/latex] and further categorized according to the other notes in the chord, as shown above. The names “Italian,” “French,” and “German” are more colorful than historical, but each chord is based on this characteristic interval.
active notes: each one resolves to sol [latex](\hat5)[/latex] from a minor second away.
shows the specific scale degrees of the augmented sixth interval and their resolution. Notice that both notes in this interval are
Augmented sixth chords are another strategy for creating harmonic intensification with chromaticism. They are mostly used as a predominant harmony (though they can serve an embellishing function as well—see Common-Tone Chords), and they lead directly to root-position V at a cadence point. They may intensify the push toward half and authentic cadences, and the V chord may have a seventh and/or include a [latex]\mathrm{cad.^6_4}[/latex]. shows all three types in a simple cadential setting (authentic cadence versions). Note that you can expect that le [latex](\downarrow\hat6)[/latex] will be the bass for this chord, but fi [latex](\uparrow\hat4)[/latex] can be in any other voice. The Ger+6 is typically followed by a [latex]\mathrm{cad.^6_4}[/latex], which serves to offset the parallel perfect fifths that would have happened between G–D and F♯–C♯; the [latex]\mathrm{cad.^6_4}[/latex] may follow the other types as well. In a four-voice texture, the Fr+6 and Ger+6 don’t require doubling; in the It+6, which has only three uniqu