Augmented sixth

The augmented sixth (A6) spans 10 semitones. It is an expanded sixth with strong directional pull, often tied to chromatic predominant function and dramatic resolution.

Construction and spelling

A6 is formed by raising a major sixth by one semitone, for example C-A#. In equal temperament it may sound like m7, but the spelling identifies sixth-function voice-leading. This distinction is important in tonal analysis.

Harmonic and melodic usage

Harmonically, A6 is associated with augmented-sixth sonorities that resolve outward to the dominant. Melodically, it has a wide, urgent profile and often implies expansion before release. Its main role is functional tension.

Examples

• Italian/French/German augmented-sixth contexts
• Chromatic predominant to dominant motion
• Expressive melodic leaps with strong resolution tendency

In practice

Practice A6 with clear spelling and resolution targets. Compare it with m7 to separate notation function from raw pitch distance. Hearing A6 functionally improves advanced harmony reading.