MUS 112 Study Guide Q (Chapter 17)

Harmonic Sequence

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  1. Harmonic sequence is defined as a series of chords with a repeating pattern of root movement.  Following are some general characteristics to look for in sequences:

    A minimum length for a harmonic sequence is four chords–the given intervallic relationship and one repetition.

    The intervals of root movement refer to their letter-name sizes.  Down a fifth from F could mean either B or Bb, according to the key.

    Root movements not common otherwise are used freely, such as ii-vi and viio–IV.

    Any diminished triad may be used with its root in the bass (in a sequence).

    In a minor key, use of the minor dominant (v) and the major subtonic (VII) is common.

    The sequence need not begin or end on the tonic, though it frequently does.

    Inversions may be used as long as the bass line itself displays a melodic sequence.  For example, a sequence may alternate between first inversion and root position, resulting in the bass line moving up a second and down a third.

    The harmonic sequence is usually accompanied by melodic and rhythmic sequence in the upper voices.

    (The sequences described below are the most common, but others do exist and are based on the same principles.)

  1. Roots Down a Fifth and Up a Fourth (descending by seconds):  This is the familiar "circle progression" sequence.

  1. Roots Up a Fifth and Down a Fourth (ascending by seconds):  This is the reverse of the previous sequence, resulting in movement backward through harmonic progressions by fifths.  In minor keys, sequences other than down a fifth/up a fourth run into problems because of the conflict with the 6th and 7th scale steps.  This sequence, up a fifth/down a fourth, is best limited in minor to that portion from VI to i.
  1. Roots Down a Third and Up a Fourth (ascending by seconds):  often called an "ascending 5 6" sequence–the fifth of the triad moves up a step, followed by the two remaining tones up a step.  (If all three notes moved together, the result would be parallel fifths.)  It is in this manner that this sequence is generally used–root position alternating with first inversion.  (The complete series is long, requiring in major fourteen root movements before all possibilities are shown.  In practice, only sections of the sequence are normally used.)

Writing this sequence in four voices produces what looks and sounds suspiciously like hidden octaves on a continuing basis.  For this reason, the sequence is used more in three-voice writing.

Also, in minor this sequence produces difficulty in dealing with scale degrees 6 and 7.

  1. Roots Down a Third and Up a Second (descending by seconds):  This sequence can be used in either major or minor.  It is best used in minor, though in major it can be effective if viio-V is avoided.
  1. Roots Down a Fourth and Up a Second (descending by thirds):  Due to problems created with diminished chords in major and minor, the portion of this sequence most commonly used is, in major:  I-V-vi-iii-IV-I; in minor:  i-v-VI-III-iv-i.
  1. First Inversion in Series:  Writing triads in parallel inversion is somewhat allied to the concept of harmonic sequence, in that repetition of an idea is involved.  Here, no consideration of chord succession is necessary.

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