What is the augmented eleventh interval?
The augmented eleventh is the compound form of the tritone(augmented fourth), projecting that interval's unique tension across a wider register. In jazz theory, the ♯11 is the preferred extension over major chords because the natural 11th clashes with the major third by a half step. Raising the 11th eliminates this conflict and produces a bright, ethereal quality associated with the Lydian mode—the fourth mode of the major scale.
The ♯11 has become a signature sound in modern jazz harmony. When a pianist plays a Cmaj7♯11 chord, the F♯ (the augmented eleventh) floats above the major seventh harmony, creating a sound that is simultaneously grounded and otherworldly. This quality has made the Lydian dominant sound a favorite of composers from George Russell (who wrote an entire theoretical framework around the Lydian concept) to film composers seeking to evoke wonder and transcendence.
Harmonic character
Despite being built on the tritone—traditionally the most unstable interval—the augmented eleventh achieves a paradoxical stability in context. When placed above a major seventh chord, the ♯11 adds brightness without the urgency to resolve that characterizes the tritone in dominant function. This is because the wide spacing and rich harmonic context transform the tritone's tension into luminous color.
- Compound equivalent: tritone + octave
- Consonance: Colorful tension, context-dependent
- Common chord context: Lydian chords, maj7♯11, dominant 7♯11
- Genre associations: Jazz, film scores, progressive rock
Where you'll hear it
The augmented eleventh is the defining interval of the Lydian mode, which has been extensively explored in jazz since George Russell's "Lydian Chromatic Concept of Tonal Organization." Miles Davis's recordings from the late 1950s onward frequently feature Lydian harmonies, and the ♯11 sound became a hallmark of modal jazz. Pat Metheny, Wayne Shorter, and Maria Schneider all make extensive use of ♯11 voicings in their compositions.
Film composers reach for the ♯11 to score moments of awe, discovery, and wonder. John Williams's scores often feature Lydian passages during scenes of magical revelation or vast landscapes. The interval also appears in progressive rock—bands like Yes and Genesis used Lydian-flavored chords to create their characteristic expansive, otherworldly sound. In contemporary pop, the ♯11 adds sophistication to chord progressions in artists like Jacob Collier and Snarky Puppy.
Practice ideas
Play a C major scale but raise the fourth degree to F♯ to hear the Lydian mode—the ♯11 is the note that distinguishes Lydian from regular major. Practice building maj7♯11 voicings in all keys. Compare the perfect eleventh with the augmented eleventh to hear how one semitone transforms the interval from neutral suspension to bright luminosity. Improvise over a static major seventh chord using the Lydian mode, emphasizing the ♯11 to train your ear for this distinctive sound.