V. Chromaticism
Augmented Options
Mark Gotham
Key Takeaways
- much rarer than the other three triad types (major, minor, and diminished).
- interesting for several reasons including:
- that rarity itself, and
- the symmetrical construction, which creates potential flexibility and ambiguity (just like with the diminished seventh chord)
- most often seen in one of two forms:
- as III+ in harmonic minor (this being the only form in the major/minor system without chromatic alteration), and
- as a chromatic passing chord between V and I in a major key: V, V+, I.
Aren’t we forgetting something here? We’re now well into chromatic harmony, yet we’ve hardly mentioned one of the four types of ostensibly diatonic triads: we’re up to speed with augmented sixth chords, but not the augmented triad. So what is this augmented triad all about? How do composers use it? How have we neglected it so long (and why do so many textbooks brush over it altogether)?
Recall that we have four types of triads that can be constructed with major and minor thirds alone:
- Diminished triad (minor third + minor third)
- Minor triad (minor third + major third)
- Major triad (major third + minor third)
- Augmented triad (major third + major third)
So the augmented triad is part of this set of possibilities, but apparently not an equal member, at least not in the eyes of common practice composers. Clearly major and minor triads are mission critical to tonal music, and so is the diminished triad, especially in its dominant function role (as viio and as a part of V7). The augmented triad is a slightly peripheral character in relation to those protagonists.
Always Chromatic?
Part of that rarity has to do with the structure of the major/minor system itself: III+ in harmonic minor is the only time the augmented triad appears in the major/minor system without chromatic alteration. This III+ triad is closely related to both the dominant (V) and minor tonic (i): in both cases, two scale degrees are held common and only one semitone distinguishes the chord tone which changes:
- III+ and V: [latex]\hat5[/latex] and [latex]\hat7[/latex] in common, semitone between [latex]\hat2[/latex] and [latex]\hat3[/latex];
- III+ and i: [latex]\hat3[/latex] and [latex]\hat5[/latex] in common, semitone between [latex]\hat1[/latex] and [latex]\hat7[/latex].
Overall, I’d say that the sound and usage of III+ typically suggests a dominant function. See what you think of the following example from the opening of Schubert’s “Der Atlas” (
) in which:- B♭ and D remain constant throughout ([latex]\hat3[/latex] and [latex]\hat5[/latex]).
- G moves to F♯ and back ([latex]\hat1[/latex] and [latex]\hat7[/latex]).
- This arguably gives the impression of a tonic-dominant alternation, but with very slight changes.
Here is the entire song:
Schwanengesang, D.957 by OpenScore Lieder
The small steps between these chords relate to a key part of the “parsimonious voice leading” that’s so important to the “Neo-Riemannian” approach