A#maj9#11

Construction

Built from these intervals: 1-3-5-7-9-#11.

Maj9#11 is maj7 with added 9 and #11 (the raised 4th). The #11 is the defining note of Lydian mode (the major scale with a raised 4th). Unlike the natural 11, which clashes with the 3 (a half step apart), the #11 sits a whole step above the 3 -- no clash, no friction. It does form a tritone (six half steps) with the root, but surrounded by the consonance of the maj9 foundation, that tritone reads as color rather than tension.

Harmonic Function

In Roman numeral analysis (uppercase = major, lowercase = minor):

• Imaj9#11 -- Lydian tonic; the #11 replaces the natural 4th, which is the root of the IV chord. Raising it removes that subdominant association, so the chord sits as tonic without any pull toward IV.
• IVmaj9#11 -- naturally occurring in major keys; the #11 of IV is the leading tone of the key, and every note of the chord is diatonic (belonging to the key's natural scale)
• Modal color -- the Lydian chord, containing six of the seven Lydian scale degrees (1, 2, 3, #4, 5, and 7 -- all except the 6th)

The #11 is Lydian's signature. When it appears on a major chord, the mode is declared without ambiguity.

Character

Brilliant and floating. The #11 adds a magical, otherworldly quality to the maj9 foundation -- this chord seems to hover above the ground. Compare to maj11 (1-3-5-7-9-11): the natural 11 creates internal friction with the 3, producing complexity and tension. The #11 resolves that friction entirely, replacing grind with glow. Compare to maj13#11: adding the 13 completes the full Lydian scale, making the sound wider and warmer.

Related Sounds

These chords are closely related -- each modifies one interval or adds an extension:

• maj9 (1-3-5-7-9) -- no 11th at all, simpler major extension
• maj11 (1-3-5-7-9-11) -- natural 11, has the 3-11 clash that #11 avoids
• maj13#11 (1-3-5-7-9-#11-13) -- add the 13th to complete the full Lydian mode as a chord
• 7#11 (1-3-5-b7-#11) -- Lydian dominant (fourth mode of melodic minor), the b7 changes function
• Pairs with Lydian mode -- the chord contains six of the seven Lydian scale degrees (all except the 6th)

Voice Leading

Voice leading tracks how individual notes move from one chord to the next. The #11 provides distinctive voice-leading options rooted in its Lydian identity. On the IV chord, the #11 is the key's leading tone, creating especially smooth connections.

• IVmaj9#11 to V7: The #11 of IV holds as the 3 of V -- a common tone that anchors the progression. The 7 of IV moves to the 5 or holds. Smooth subdominant to dominant.
• Imaj9#11 to V7: The #11 moves up a half step to the root of V. The 7 moves to the b7 of V or holds. The half-step resolution of #11 to the dominant root is clean and direct.
• Imaj9#11 to ii7: The #11 moves down a half step to the b3 of ii. The 9 holds as the root of ii. The #11 resolves chromatically into the minor color.

These movements apply in any key -- the intervals are the same regardless of root.

Practice Seeds

Lydian identity. Play maj9#11, then the Lydian scale (the major scale with a raised 4th). Hear six of the seven scale tones present in the chord -- only the 6th is missing. This is Lydian made nearly vertical.

No clash. Play maj9#11 back to back with maj11 (natural 11). The #11 floats; the natural 11 grinds against the 3. One interval changes the entire character.

IV chord in context. Play IVmaj9#11 to V7 to Imaj7 in a major key. The #11 of IV is the leading tone of the key, and it resolves naturally into the V chord. Hear Lydian function in action.

Wonder voicing. Arrange the chord so the #11 sounds as the highest note -- even in a partial voicing, placing the #11 on top highlights the floating, expansive quality that makes this chord evocative in film scores.