Definition
Prolongation is the idea that a chord (or a function) remains active even when other chords are sounding in the moment. The intervening chords are ornaments (neighbor, passing, arpeggiated) of the prolonged chord. It is the central concept of the analysis of Heinrich Schenker (1868–1935) and of the texts derived from him, such as Harmony and Voice Leading by Aldwell and Schachter.
Levels
- Surface (foreground): all the notes and chords.
- Intermediate level (middleground): the structural chords and main lines remain.
- Deep level (background): the Ursatz, that is, a descending line in the upper voice (3–2–1 or 5–4–3–2–1) over a I–V–I bass.
Each level “prolongs” the one below.
Techniques for prolonging the tonic (C major)
| Technique | Example | Description |
|---|---|---|
| Neighbor chord | C – F/C – C | the IV over a C pedal embellishes the tonic |
| Passing chord | C – Dm7 – C/E | the bass rises C – D – E by step, the Dm7 is only passing |
| Passing six-four chord | C – G/D – C/E | same bass, but with the V in second inversion (passing V6/4) |
| Neighbor (pedal) six-four chord | C – F/C – C | same logic, written as IV6/4 |
| Bass arpeggiation | C – C/E – C/G | the tonic “moves” without changing |
| Voice exchange | C (bass C, E above) – C/E (bass E, C above) | bass and soprano swap notes |
| Neighbor dominant | C – G7/B – C | the incomplete V embellishes the tonic |
Prolongation of the dominant
- Cadential six-four: C/G – G7 – C. The C/G is not a tonic, but a dominant with two appoggiaturas (C and E falling to B and D): it prolongs G.
- Dominant pedal with chords above (C/G – F/G – G7): typical of fugues and endings.
- The omnibus progression prolongs a dominant over several chords.
Real example: Bach, Prelude in C, BWV 846
Bars 1–4: C – Dm7/C – G7/B – C. The bass stays on C (then B, then C): the tonic is prolonged with a neighbor chord (Dm7/C) and a neighbor dominant chord (G7/B). At the deep level, the four bars are a single C chord. The entire prelude is one great prolongation of the tonic that closes with a long dominant pedal (from about bar 24) and a final tonic pedal.
Prolongation in modern music
- Pop: C – C/B – Am – … the bass descends, but the first two chords prolong the tonic.
- Jazz: a ii–V can be read as a prolongation of the dominant (the ii is an “ornament” of the V); a I–vi–ii–V turnaround prolongs the tonic.
- EDM: a tonic pedal with chords changing above is a tonic prolongation lasting 16–32 bars.
Why it is useful to the producer
- Understanding which chord is structural tells you which chords you can substitute freely (those of prolongation) and which you cannot.
- It helps you write basses: move the bass by step between two structural chords.
- It helps you gauge the perceived harmonic rhythm: many surface chords can sound like a single one.
Exercise
- Write 4 bars that prolong C using the table: C – F/C – C/E – G/D – C.
- Do the same for G with a G pedal: G – C/G – D7/G – G7.
- Connect the two parts: you have a T – D – T phrase in which each function lasts 4 bars, but the surface is rich.
Related topics
Pedal and ostinato, advanced pedal point, inversions and six-four chords, non-chord tones, advanced harmonic rhythm, omnibus progression.