Harmonic Sequences
Take a short pattern, move it a step, and repeat. The listener recognises the shape the second time and can predict it the third, which buys you eight bars of music from two bars of ideas. It is the oldest way to make a passage sound both inevitable and alive.
- 1 model
- 2 or 3 copies
- moves by a fixed step
In which styles
- Classical
- Jazz
- Film music
- Prog
In short
A sequence works on pattern recognition. The first statement is information; the second says the pattern is deliberate; the third confirms it and lets the listener predict. Stop after the third and the prediction is left hanging, which is why sequences so often break exactly there and land somewhere unexpected.
Purposeful and slightly mechanical. A sequence sounds like machinery in the best sense: something is turning, and it will keep turning until it arrives.
Where it sits in the phrase
Sequences fill the middle of a phrase, between a statement and a cadence. They are the connective tissue of classical development sections and of jazz bridges, and they almost never open or close a piece, because a pattern needs something to be a variation of.
Where you run into this
- A classical development where one short figure keeps coming back a step lower
- The bridge of a standard, moving through keys in a regular pattern
- A film cue building tension by repeating one gesture upward
The types side by side
The descending fifths sequence is the strongest, because every step is a cadence in miniature. Descending thirds is gentler. Ascending seconds builds. The rosalia, a sequence rising by step, sounds heroic and dates quickly. Play them next to each other and you hear that the direction and the interval, not the chords, decide the character.