21.7: Descending Chromatic Bass Lines
A common musical pattern is the descending chromatic bass line (1^ –7^ –♭7^ –6^ –♭6^–5^ ). Composers harmonize descending chromatic bass lines with all manner of harmonies, including secondary chords, borrowed chords, augmented sixth chords, and rarely-used diatonic chords. Below are some examples from the past four centuries.
Below is a table comparing the harmonizations of these descending bass lines.
| Bass Line | 1^ | 7^ | ♭7^ | 6^ | ♭6^ | 5^ |
|---|---|---|---|---|---|---|
| Purcell | ii | VV6 | VivV24/iv | IVIV6 | iviv6 | VV |
| Bach | ii–viiVvii∘34/V | VV6 | viivii7–viiivvii∘34/iv | IVIV6 | iviv6–FrFr+6 | ii46–VV6 |
| Beethoven | ii | VV6 | VivV24/iv | IVIV6 | GerGer+6 | ii46 |
| Beatles | ii | ii24 | IVIV56 | VIVI | ||
| Led Zeppellin | ii | IIIIII+M34 | ii24 | IVIV6 | VIVIM7 | |
| Aerosmith | ii | ii24 | ♯vi ø viø7 | VIVIM7 | ||
| S.T.P. | ii | VV6 | VivV24/iv | ♯vi ø viø7 | (VIVI) | |
| Perri | ii | VV6 | ii24 | IVIV6 |
For the harmonization of scale degree 6^ , remember that the concept of ♯vivi∘ was introduced when Roman numerals in minor were introduced. The notes of the ♯vi ø viø7 chord belong to the melodic minor scale.