Reharmonizing Classic Chord Progressions - Their Magic and Effect
The classic chord progression 'Ⅶm7♭5 → Ⅲ7 → Ⅵm7' is a sequence frequently used in pop and jazz, known for its poignant and jazzy sound.
For example, in the key of C, this progression becomes 'Bm7♭5 → E7 → Am7'.
Structure of the Chord Progression
This progression can be interpreted as a variation of the so-called 'two-five-one (Ⅱ-Ⅴ-Ⅰ)' in the key of A minor.
Bm7♭5 (Ⅱm7♭5): A chord with a subdominant function in the key of A minor.
E7 (Ⅴ7): A dominant seventh derived from the A harmonic minor scale. This creates a strong sense of resolution to the following Am7.
Am7 (Ⅰm7): The tonic (root) of the A minor key.
The strong dominant motion of E7 allows for a comfortable and settled feeling.
The Key to Reharmonization
Parallel Keys and Relative Keys:
The reharmonization that transforms this classic progression into the richer and more dramatic 'Ⅶm7♭5 → Ⅲ7 → Ⅳmaj7 → Ⅴ → Ⅵsus4 → Ⅵmaj' skillfully utilizes the concepts of parallel keys and relative keys.
For example, by intentionally avoiding the Am7 that would normally follow the original progression (Bm7♭5 → E7 → Am7), you provide the listener with an unpredictable development.
Development from Ⅲ7 (E7):
E7 is the dominant seventh (Ⅴ7) of A minor, which is the relative key of C major, while simultaneously functioning as a Ⅴ7 borrowed from A major, the parallel key of A minor.
Transition to Ⅳmaj7 (Fmaj7):
By progressing to Fmaj7, the Ⅳmaj7 of C major, instead of resolving to Am7 after E7, it suggests a return to the original key (C major).
Dramatic Resolution:
After that, it moves toward Ⅵ (A) via Ⅴ (G), but here, an Asus4 → Amaj movement is added.
This signifies a resolution to A major, the parallel key of A minor. This shifts the mood from the original 'introspective poignancy' to a bright and hopeful sound.
Effects of Reharmonization
This reharmonization does more than just change chords; it brings new stories and emotions to the music, such as:
Unpredictable development:
It subverts listener expectations in a positive way, sparking interest in new harmonies.
Colorful harmony:
In addition to the original A minor sound, the brightness of C major and the brilliance of A major blend together, adding depth to the music.
Dramatic change in atmosphere:
The movement from Asus4 to Amaj creates an emotional and dramatic sound, much like sunlight peeking through a cloudy sky.
In this way, chord progressions are not just a sequence of notes, but like words that stir the emotions of the listener.
This time, we introduced a powerful technique to enrich the expression of a song through chord borrowing from parallel and relative keys.