Sequence refers to the repeated repetition (also with variations) of a musical phrase in the same voice on another level of the scale. Usually the direction (up = rising or down = falling) is maintained. The real sequence preserves the intervals between all notes, which is only possible with modulation and therefore leads to another key; in a tonal sequence the key remains the same, which is why the intervals must change in some places.

Example

Mozart, Piano sonata K. 331

The period begins with a minor third (E-G-G), continues in a minor third (D-E-F) and ends in a major third (C-D-E). This is called a falling tonal sequence.

Descending fifths

Particularly frequent is the displacement by a fifth down, referred to as descending fifths. For example, if the phrase starts with C in the first pass (the model), use F in the repeat, and so on. The order can be easily remembered with the following left-to-right and top-to-bottom table:

LevelLevelExample: C major
1 4 C F
7 3 H E
6 2 A D
5 1 G C

Thus, in the first seven iterations, no chord is played twice. However, in practice rarely more than three iterations occur.

Decending thirds

The root note of each iterations descends in thirds. Frequently, the third-fifth chord = root position for the first chord of the model and the third-sixth chord (third-bass) = 1st inversion is used for the second (“descending 5-6”).

Pachelbel sequence

The popular Pachelbel sequence is a descending fourth-third sequence.