Augmented Scale

The augmented scale alternates minor thirds and half steps. Like the whole tone and diminished scales, it's symmetrical — it divides the octave into two equal parts. The sound is ambiguous and floating, with no clear tonal centre. It's less commonly used in jazz than the whole tone or diminished scales, but it appears in 20th century classical music and in the playing of some jazz musicians who favour symmetrical scales.

Construction

C augmented scale:
C  E♭  E  G  G#  B  C
   m3  H  m3  H  m3

Formula: 1  ♭3  3  5  ♯5  7

Six notes, alternating minor thirds and half steps.

There are only four distinct augmented scales (compared to three diminished scales). Each group of three roots shares the same six pitches:

Group 1: C, E, G#/A♭    → C E♭ E G G# B
Group 2: C#, F, A       → C# E F A A# C
Group 3: D, F#, A#/B♭  → D F F# A A# C#
Group 4: D#, G, B       → D# F# G B C D

Sound and Character

Unsettled, neither major nor minor, hovering. The scale contains both the major third and the augmented fifth (♯5) — this is exactly the augmented triad (root, M3, ♯5). The ambiguity comes from the equal spacing: like the whole tone scale, you can't quite find a home within it. It sounds like something is slightly off — suspension without resolution.

Use Over Augmented Chords

Caug chord: C E G#
C augmented scale: C E♭ E G G# B

The chord tones (C, E, G#) are all in the scale.
The scale adds: E♭ (♭3, chromatic colour), G (5th — major sound), B (major 7th)

The augmented scale works over augmented triads and augmented major 7th chords (maj7♯5). It also works over tonic major chords where the ♯5 or ♭13 is desired as a colour tone.

In Context

Oliver Messiaen (who called it one of his "modes of limited transposition") used it extensively in his piano and organ works. In jazz it appears occasionally in post-bop and free jazz contexts — not a core vocabulary item but available for texture. The scale's limitation is the same as the whole tone scale: symmetry creates monotony over longer passages. Short gestures are more effective than extended lines.