Short Answer
Overview
An augmented interval is a musical interval that is one chromatic semitone larger than a perfect or major interval of the same numeric size. For example, an augmented fourth spans six semitones, one more than a perfect fourth (five semitones), and an augmented major third spans five semitones, one more than a major third (four semitones). Augmented intervals are classified as dissonant in common‑practice harmony, often functioning to increase tension before resolving to a consonant interval.
Because they are derived by sharpening either the higher or the lower note of a standard interval, augmented intervals are notated with a plus sign (+) or the abbreviation “A” (e.g., A4 for an augmented fourth). Their enharmonic equivalents—intervals that sound the same but are spelled differently—include diminished intervals (e.g., an augmented fourth is enharmonically equivalent to a diminished fifth).
History / Origin
The term “augmented” comes from the Latin verb *augere*, meaning “to increase.” It entered Western music theory in the Baroque era, when composers began to codify interval classification in treatises such as Johann Joseph Fux’s Gradus ad Parnassum* (1725). The systematic distinction between perfect, major, minor, diminished, and augmented intervals was solidified during the Common Practice Period (c. 1650–1900), providing a framework for functional harmony that persists in modern theory.
How It’s Used
Augmented intervals appear in melody, harmony, and voice leading. In tonal music they often function as leading‑tone structures, such as the augmented fourth in the “tritone substitution” in jazz. Composers use augmented intervals to create chromatic color, as in the opening motive of Beethoven’s Symphony No. 5 (the famous “short‑short‑short‑long” motif contains an augmented fourth). In contemporary film scoring and progressive rock, augmented intervals can convey suspense or otherworldly atmospheres.
Why It Matters
Understanding augmented intervals is essential for analyzing harmonic tension and resolution. They serve as pivot points for modulation, provide the basis for altered dominant chords (e.g., G7♯5), and enrich melodic contour. Listeners often perceive the characteristic “sharp” quality of an augmented interval, which can heighten emotional impact in a passage. Notable examples include the opening chord of “Maria” from *West Side Story* (an augmented triad) and the bridge of Radiohead’s “Paranoid Android,” which employs augmented intervals to destabilize the tonal center.
Common Misconceptions
An augmented interval is the same as a diminished interval.
They are enharmonically equivalent in pitch but differ in spelling and harmonic function; an augmented interval is built from a perfect or major base, while a diminished interval comes from a perfect or minor base.
Augmented intervals are always dissonant and should never be used in consonant contexts.
Although classified as dissonant, augmented intervals can resolve to consonances and are deliberately employed for expressive purposes in many musical styles.
FAQ
How is an augmented interval spelled in notation?
It is indicated by adding a sharp sign to the upper note (or a flat to the lower note) and labeled with an “A” or plus sign, such as A4 or +4.
Can an augmented interval appear in a major scale?
In a diatonic major scale, augmented intervals do not occur naturally, but they can be created through chromatic alteration or modal mixture.
What is the difference between an augmented fourth and a tritone?
The term “tritone” refers to any interval spanning three whole tones (six semitones). An augmented fourth is one specific spelling of a tritone, while the same pitch distance can also be spelled as a diminished fifth.
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