Augmented Scale

The augmented scale alternates minor thirds and half steps. Like the whole tone and diminished scales, it's symmetrical — each note is equidistant from its neighbours in a consistent pattern. The sound is ambiguous and floating, with no clear tonal centre. It appears in 20th century classical music (Messiaen catalogued it as one of his "modes of limited transposition"), and it occasionally surfaces in jazz when a player wants an augmented or unsettled major colour over tonic chords.

Construction

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

Pattern: alternating minor 3rd (m3) and half step (H)
Six notes per octave.

Formula: 1 — ♭3 — 3 — 5 — #5 — 7

Note: the scale contains both the minor 3rd (E♭) and the major 3rd (E),
and both the perfect 5th (G) and the augmented 5th (G#).
This ambiguity — neither clearly major nor minor — is the scale's character.

Only Four Distinct Augmented Scales

The augmented scale divides the octave into three equal parts (two minor thirds + one half step repeated × 2 = 12). This means transposing up a major third gives the same set of pitches — there are only four distinct scales:

Group	Shared roots	Notes
1	C, E, G#/A♭	C E♭ E G G# B
2	C#/D♭, F, A	C# E F G# A C
3	D, F#/G♭, A#/B♭	D F F# A A# C#
4	D#/E♭, G, B	D# F# G B C D

Sound and Character

Unsettled, suspended, hovering between major and minor. The scale contains the augmented triad (root, M3, ♯5) — three notes that divide the octave into equal major thirds, creating the same type of ambiguity as the whole tone scale but with a different structure. Since every pattern repeats every major third, a lick sounds the same when transposed by a major third — which is both a convenience (three keys for one pattern) and a limitation (everything sounds similar).

Over Augmented Chords

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

Chord tones in scale:
  C  = root ✓
  E  = major 3rd ✓
  G# = augmented 5th ✓

Extra notes provided:
  E♭ = minor 3rd (chromatic colour, adds ambiguity)
  G  = perfect 5th (natural — gives a "both" quality)
  B  = major 7th (adds an augmented-major 7th sound)

Result: works over Cmaj7#5 (augmented major 7th chord), Caug, and over
tonic major chords where #5 or ♭6 colour is wanted.

In Classical Music: Messiaen

Olivier Messiaen listed the augmented scale as the third of his seven "modes of limited transposition" — modes whose interval patterns limit how many distinct transpositions exist. Messiaen used it in his organ works (notably La Nativité du Seigneur) and piano pieces for its floating, spiritual quality. For Messiaen, the symmetrical modes represented the "colours of sound" — each had a visual or emotional character he described synesthetically.

Comparison with Other Symmetrical Scales

Scale	Notes per octave	Pattern	Distinct versions	Character
Whole tone	6	All whole steps	2	Dreamy, floating, no tension
Diminished	8	H-W alternating	3	Tense, dissonant, unstable
Augmented	6	m3-H alternating	4	Ambiguous, hovering, neither major nor minor

Practical Note

The augmented scale is less commonly used in jazz than the whole tone or diminished scales. It works best in short passages — a few beats or a measure — where its unusual sound creates a brief moment of ambiguity before resolution. Extended augmented scale playing becomes monotonous for the same reason as whole tone: the equal spacing removes all pull and contrast. It's a texture and colour tool rather than a primary improvisational vehicle.

References

• Messiaen — The Technique of My Musical Language
• Levine — The Jazz Theory Book
• musictheory.net ↗