The augmented fifth (A5) spans 8 semitones. It is a widened fifth with a bright, tense color often used in altered harmony and chromatic writing.
Construction and spelling
A5 is built by raising a perfect fifth by one semitone, for example C-G#. Even when it sounds like m6 in equal temperament, the spelling signals expanded-fifth function. This matters for harmonic meaning.
Harmonic and melodic usage
Harmonically, A5 appears in augmented triads, altered dominants, and coloristic chord voicings. Melodically, it creates lift and instability. It is useful when you want intensity without the exact profile of a minor sixth spelling.
Examples
- Augmented triads in film and late-romantic textures
- Altered dominant sonorities in jazz harmony
- Chromatic voice-leading with raised fifth tendencies
In practice
Practice A5 against P5 and m6 to separate spelling from sound. Voice-lead A5 into stable intervals to hear directed resolution. Accurate A5 recognition strengthens altered-harmony fluency.
