23 May 2004

Notes: Chapter 11 from Harmony, Walter Piston

I've been re-reading chapters from Walter Piston's book Harmony, 3rd Edition.

Chapter 11 is titled "Harmonic Rhythm."

  • Meter & Rhythm
  • Rhythm denotes where the strong beats are placed within the music. Meter denotes measures in the music. Meter has no rhythm. Meter is a convenience used to segment the music in a manner that best reflects the rhythm.

    Rhythm before the 1700s and 1800s was more like those of fine prose. That changed partly with the importance put on dance forms. Piston provides an example from the Sarabande from Bach's Second English Suite. A sarabande is a 3/4 dance with the stress on the second beat. Interesting that although the rhythm is strict, the different dance forms introduced some variations.

    Anacrusis is the up-beat. Thesis is the down-beat. Either may have the stress.

  • Melodic and Harmonic Rhythm

  • Harmonic rhythm looks at the root changes (chord changes) in isolation from the notated rhythm. There can be multiple root changes within a measure, and roots that hold across measures (syncopation). Changes can be very irregular to add interest.

    Harmonic rhythm can match the melodic rhythm (that of the melody). This occurs in homophonic music.

    Melodies can be accompanied by a regular harmonic pulse in order to highlight the melodies' expressiveness.

    The two main features of harmonic rhythm are frequency of root change and rhythmic quality (the duration of the resulting root changes).

  • General Rules/Notes

  • Complicated chromatic part-writing (characteristic in late 1800s romanticism) can obliterate the feeling of harmonic progression.

    Frequent root changes evoke a restlessness. Infrequent root changes relaxation.

    Long notes are rhythmically stronger regardless of where they are in the meter. (This is separate from harmonic rhythm.)

    Chord progressions are strong (ending on a strong beat) when the root moves by fourth, fifth, or second; weak when the root moves up a third. These can only help suggest the rhythm when combined with all other features, and the effects become more complex with more root changes in the phrase.

    Faster music may swallow passing chords into a larger harmonic scheme. This would give the impression of less frequent root changes.

    Harmonic rhythm may still be heard over bass pedals if the upper voices assert their dominance.