Melodic Sequence

A sequence starts with a short pattern of notes, the model, usually two to four notes long. The composer then repeats that same shape immediately, but shifted up or down by a fixed interval. Repeat that shift again, using the same interval each time, and you get a chain of segments that all share the same melodic contour while climbing or falling through the key. Because the interval of transposition stays constant, your ear locks onto the pattern of motion itself, not just the individual notes. That's why a sequence falling by a second each time feels like it's tumbling downstairs: each step is the same size, so the motion reads as continuous descent rather than a series of unrelated leaps.

The transposition is usually diatonic, meaning the segment is respelled to fit the notes available in the key, so the exact pattern of half steps and whole steps inside the figure can shift slightly from repetition to repetition. A real sequence needs a consistent interval of transposition and a consistent number of repetitions happening right after each other; change the interval randomly each time and you just have a repeated figure, not a sequence.

Sequences connect directly to the embellishing tones studied earlier in the unit, since passing tones, neighbor tones, and suspensions often get caught up in the repeating figure and sequence right along with it. Spotting a sequence also helps you predict where a melodic line is headed, since once you know the model and the interval of transposition, you can figure out every later segment without hearing it.