Augmented

Widened by a semitone

An augmented interval is a semitone larger than the perfect or major one. The augmented fifth has eight semitones instead of seven. Two major thirds (4 + 4 semitones) give exactly this fifth, and the augmented triad is built from them, for example C–E–G♯. It sounds floating and hard to place, because its fifth is widened. Like all unstable chords it asks for resolution.

Where it occurs

In harmonic minor there is an augmented triad on the third degree: in A minor that is C+, C–E–G♯, when the G♯ from the raised seventh degree is used. This chord appears in the table on the page A minor. That is also where the augmented second arises between the sixth and seventh degrees, the characteristic, hard-to-sing step that gives harmonic minor an exotic, eastern-sounding flavour.

The augmented triad is symmetrical: it consists of two major thirds, and the gap up to the octave is just as large. That makes it ambiguous, much like the diminished seventh chord.

Common mistakes

• Confusing it with the major triad: The augmented triad has two major thirds, major has one major and one minor.
• Confusing it with diminished: Diminished consists of two minor thirds, augmented of two major thirds.
• Writing the augmented second as a minor third: Both sound the same but have a different function and spelling.