3

The French sixth chord sounds more dissonant than the Italian and German sixth chords. What is the reason?

4

It's because the French 6th chord has an extra tritone.

If we take an Ab Augmented 6th chord, we would have:

Ab C D F#

Ab to D and C to F# are both tritones.

By contrast, the Italian and German versions would only have one: C to F#.

  • 1
    So, it is like a diminished 7th(which is also 2 overlapping trritones) but based on the major chord instead? – Caters Feb 13 '19 at 17:47
  • 1
    @Caters I've never thought about it that way. It's true that they both contain two tritones, but their harmonic function is different enough that I'm not sure it is a fruitful line of thinking in any deep sense. But I suppose it does explain why they have similar amounts of dissonance. (The whole step in the FrAug6 is why it sounds even clashier than then dim7) – Ben I. Feb 13 '19 at 20:08
  • Ah, now I got it! While the Italian and the German sixth chords have only one, the French sixth has TWO tritones, the A4 / d5 intervals, which are EXTREMELY dissonant. The tritones are known as "Devils", which were banned in early church music! – user53472 Feb 20 '19 at 5:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy