The augmented chord is a unique and evocative harmony characterized by its symmetrical structure and sense of unresolved tension. Built from a major triad with a raised fifth, it creates a sound that feels "lifted," mysterious, or in need of resolution. Often notated as C+, Caug, or C♯5, this chord lacks the stability of a major or minor triad, instead acting as a bridge that propels the music forward. Its distinctive quality comes from the augmented fifth interval, which divides the octave into three equal major thirds, giving the chord a floating, ambiguous character.
Unlike the dominant seventh, which has a clear directional pull to a specific tonic, the augmented chord can resolve to multiple different destinations. This versatility makes it a favorite tool for composers and improvisers looking to add color, suspense, or a sense of "otherworldliness" to a progression. It is frequently used to modulate to new keys, heighten emotional climaxes, or create a dreamlike atmosphere.
Construction and Definition
Musically, the augmented chord is constructed by stacking two major thirds on top of the root. In the key of C, a C augmented chord contains the notes C–E–G♯. The critical theoretical element is the interval between the root and the fifth, which is an augmented fifth (or sharp five). This interval is wider than the perfect fifth found in a major triad, creating a sense of expansion and instability. Because the chord is built from two identical major thirds (C to E, and E to G♯), it is perfectly symmetrical; this means that C+, E+, and G#+ are essentially the same set of notes, just rooted differently.
This symmetry is both its strength and its ambiguity. It allows the chord to function as a pivot in modulation, as it can seamlessly lead to several different keys. The lack of a perfect fifth removes the grounding effect of a standard triad, leaving the listener with a feeling of suspension. The augmented fifth has a natural tendency to resolve outward: the G♯ often moves up to A (the sixth of the relative minor) or down to G (the fifth of the relative major), creating a smooth voice-leading resolution.
Harmonic and Melodic Usage
The augmented chord serves several specific functions in harmony, primarily acting as a passing chord or a dominant substitute. In classical music, it is often used as a V+ chord that resolves to the tonic, adding extra tension before the final cadence. In jazz and pop, it frequently appears as a I+ chord to create a sense of movement within a static major key, or as a III+ chord to lead to the relative minor.
Key usage contexts include:
- Classical Harmony: Used as a dominant substitute (V+) to intensify the resolution to the tonic, or as a passing chord between I and I6.
- Jazz & Fusion: Employed as a passing chord to connect distant harmonies, or as a substitute for a dominant chord with a sharp 11 (e.g., C7♯11 often implies C+).
- Pop & Rock: Used to create a dramatic lift in choruses or bridges, often replacing a standard major chord to add emotional weight.
- Modulation: Utilized as a pivot chord to smoothly transition between unrelated keys due to its symmetrical nature.
It is important to note that while the augmented chord is often associated with tension, it can also be used to create a sense of wonder or fantasy, particularly in film scores and impressionist music.
Examples in Music
The augmented chord is a staple of dramatic and colorful music across many genres. Its sound is instantly recognizable and versatile:
- Classical: Beethoven's "Moonlight Sonata" (first movement) uses the augmented chord to create a haunting, unresolved atmosphere.
- Jazz Standards: "Heart and Soul" features a classic I–I+–vi progression, where the augmented chord acts as a passing tension.
- Pop & Rock: "Oh! Darling" by The Beatles uses an augmented chord to heighten the emotional intensity of the chorus.
- Film Scores: Composers like Bernard Herrmann (Psycho) and John Williams often use augmented chords to signal danger, mystery, or the supernatural.
- Progressive Rock: Bands like Pink Floyd and Yes utilize augmented harmonies to create psychedelic and otherworldly textures.
In Practice
When playing an augmented chord, the most important concept is resolution. Because the chord is inherently unstable, it rarely stands alone for long. The augmented fifth (the sharp five) should typically resolve outward: moving up to the sixth of the next chord or down to the fifth. For example, in a C+ resolving to Am, the G♯ moves up to A. In a C+ resolving to C major, the G♯ moves down to G. Practicing these resolutions slowly helps internalize the chord's function as a bridge rather than a destination.
For improvisation and comping, focus on the symmetry of the chord. Since C+, E+, and G#+ contain the same notes, you can use any of these roots to imply the same harmony. This allows for smooth voice leading and creative reharmonization. When adding extensions, the augmented chord pairs well with major sevenths (creating a maj7♯5 sound) or dominant sevenths (creating a 7♯5 sound). Listen to recordings of master players to hear how they use the augmented chord to create tension and release, often using it as a "springboard" to launch into a new section or key.
