The altered scale, a seven-note musical scale, is derived from the melodic minor scale and is characterized by a flatted second, augmented fourth, flatted sixth, and flatted seventh relative to the major scale. Its structure creates a highly dissonant sound often used in jazz and other improvisational music. For example, when encountering a dominant 7th chord in C (C7), the altered scale built from C (C, Db, Eb, E, Gb, Ab, Bb) can be employed to add tension and complexity.
Its significance arises from its ability to provide a concentrated source of altered tones over dominant chords, thus injecting color and intrigue into musical passages. Historically, its systematic use became more prominent in post-bop jazz, where musicians sought to expand harmonic vocabulary and create more sophisticated improvisations. The scale’s application allows for a wider array of melodic choices that move beyond the more common and predictable diatonic options.
