The augmented second (A2) spans 3 semitones and is enharmonically close to a minor third, but its spelling reflects an expanded second. This makes it especially relevant in scale theory and chromatic voice-leading.
Construction and spelling
A2 is written as a raised second, such as C to D# or A to B#. Even when the sound can match m3, the letter naming preserves a second-based function. This distinction is important in harmonic analysis and modal contexts.
Harmonic and melodic usage
A2 often appears in harmonic minor and related modal colors, where it gives melodies an exotic or dramatic contour. In chromatic writing, it can signal directional alteration more clearly than enharmonic alternatives. Its role is both sonic and structural.
Examples
- Characteristic step in harmonic minor lines
- Chromatic melodic turns with sharpened second degree
- Analysis comparing spelled A2 and sounding m3
In practice
Practice A2 by singing and spelling it from different roots, then compare with m3 to hear same distance but different notation logic. Combine ear work with interval spelling drills. Strong A2 fluency improves theory accuracy and melodic interpretation.
