Augmented Chord
An augmented chord, also called an augmented triad, combines a root, major third and augmented fifth. C augmented is C, E and G sharp. Its equal four-semitone spacing makes the pitch collection symmetrical, while spelling, bass and resolution still establish a harmonic root.
- 1-3-sharp 5
- two major thirds
- 4 pitch-class sets
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Which notes are in C augmented?
Use the formula 1-3-sharp 5:
- C: root
- E: major third
- G sharp: augmented fifth
Symbols include Caug and C+. The sharp belongs to scale degree 5, so G sharp is the functional spelling above C.
How do you build it?
Start with C major, C-E-G, and raise G by one semitone.
The intervals C-E and E-G sharp are both major thirds. G sharp up to the octave C is also four semitones.
That equal spacing divides the octave into three parts.
Why are there only four augmented pitch-class sets?
Transpose C-E-G sharp up a major third.
E-G sharp-C uses the same equal-tempered piano keys in a new order. Another major-third transposition returns the same collection again.
Starting on C, C sharp, D and E flat gives the four distinct collections. Further semitone transpositions repeat one of them.
Does symmetry mean it has no root?
No. Context can establish C as the root of Caug through bass, notation and resolution.
The same sounding keys may be spelled E-G sharp-B sharp for Eaug or A flat-C-E for A-flat augmented.
Enharmonic spelling shows which note is root and where the altered fifth is expected to move.
Where does the raised fifth resolve?
In C-Caug-C6, G rises to G sharp and then A while C and E remain fixed.
Caug can also move to F minor: G sharp may be respelled A flat and remain as the third of Fm while E moves to F.
Voice leading is contextual. Track G sharp as an individual line instead of assigning one automatic resolution.
Where does it occur in harmonic minor?
A harmonic minor is A-B-C-D-E-F-G sharp.
Stack thirds on degree 3: C-E-G sharp. That creates Caug.
The same raised leading tone G sharp that strengthens E7 also creates the augmented III triad.
How is it different from a major triad?
C major is C-E-G. Caug raises G to G sharp.
The third remains major. Only the fifth changes from perfect to augmented.
Compare C, Caug and C6 while the upper voice moves G-G-sharp-A.
How is it different from diminished?
C diminished is C-E flat-G flat and stacks two minor thirds.
Caug stacks two major thirds. Both are symmetrical triads, but their interval sizes and pitch collections differ.
Diminished contains a tritone C-G flat. Augmented contains an augmented fifth C-G sharp.
Which scales fit it?
C whole tone contains C-E-G sharp and adds D, F sharp and A sharp.
A harmonic minor contains C-E-G sharp as its III chord and supplies a different surrounding collection.
An augmented scale can also support augmented-major sonorities. Choose from chord function and melody.
How should you voice it?
State the intended root in the bass when the harmony might be ambiguous.
Spread the notes when close low major thirds become dense. Keep the altered fifth audible if its voice leading is important.
Avoid adding an unmarked perfect fifth G to Caug because it contradicts the sharp-5 specification.
How should you practice it?
Build C major and raise G to G sharp.
Play C-Caug-C6 and sing G-G-sharp-A. Then spell the same keyboard keys as Caug, Eaug and A-flat augmented.
Resolve each spelling to a chord that confirms its written root.