Table of Contents
Augmented sixth chords are a fascinating element of Western tonal music, known for their distinctive sound and complex voice-leading. Their behavior varies across different keys, making them a captivating subject for music theorists and students alike.
What Are Augmented Sixth Chords?
Augmented sixth chords are special chords built on the interval of an augmented sixth, typically resolving to the dominant. They often include the notes ♁ (the lowered sixth), ♯ (the raised fourth or fifth), and the tonic or other chord tones, depending on the specific type of augmented sixth chord.
Types of Augmented Sixth Chords
- Italian (It): Contains the lowered sixth, the tonic, and the raised fourth.
- French (Fr): Adds the second to the Italian form.
- German (Ger): Includes the lowered sixth, the tonic, and the dominant note.
Voice-Leading Principles
The voice-leading of augmented sixth chords is characterized by their strong tendency to resolve outward to the dominant harmony. The core principle involves the resolving of the augmented sixth interval into an octave, typically with the outer voices moving by half steps.
Resolution to the Dominant
The lowered sixth and raised fourth generally resolve outward by half steps to the notes of the V chord. For example, in C major, A♭ and F♯ would resolve to G.
Voice Leading in Different Keys
The specific notes and their resolutions depend on the key. In minor keys, the augmented sixth often involves the lowered sixth degree, which resolves outward to the dominant. In major keys, the resolution remains similar but with different note choices based on the scale.
Examples of Voice-Leading in Various Keys
Consider the key of G major. An augmented sixth chord built on the lowered sixth (E♭) would resolve to G major or G7. The outer voices move by half steps: E♭ resolves upward to E, and F♯ (raised fourth) resolves downward to E.
In a minor key, such as A minor, the augmented sixth might include F♯ and D♭, resolving to E minor or E major, with similar outward half-step resolutions.
Practical Applications
Understanding the voice-leading of augmented sixth chords allows composers and performers to create smooth, dramatic resolutions that enhance emotional expression. Proper handling of these chords is essential for authentic classical style and modern harmonic experimentation.
Summary
Augmented sixth chords serve as powerful tools for establishing tension and release within a musical phrase. Their characteristic resolution to the dominant, guided by specific voice-leading rules, makes them a vital part of tonal harmony across various keys.