French sixth
| Component intervals from root | |
|---|---|
| minor sixth | |
| augmented fourth (tritone) | |
| root | |
| Tuning | |
| 41472:59049:65536 | |
|
Forte no. / |
|
| 3-8 / |
In music theory, an augmented sixth chord contains the interval of an augmented sixth, usually above its bass tone. This chord has its origins in the Renaissance, further developed in the Baroque, and became a distinctive part of the musical style of the Classical and Romantic periods. Conventionally used with a predominant function (resolving to the dominant), the three more common types of augmented sixth chords are usually called Italian sixth, French sixth, and German sixth.
The augmented sixth interval is typically between the sixth degree of the minor scale (henceforth ♭6) and the raised fourth degree (henceforth ♯4). With standard voice leading, the chord is followed directly or indirectly by some form of the dominant chord, in which both ♭6 and ♯4 have resolved to the fifth scale degree (henceforth 5). This tendency to resolve outwards to 5 is why the interval is spelled as an augmented sixth, rather than enharmonically as a minor seventh (♭6 and ♭5). Although augmented sixth chords are more common in the minor mode, they are also used in the major mode by borrowing ♭6 of the parallel minor scale.
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