Harmonic Rhythm

Harmonic rhythm is the speed at which the chords change. It is separate from the rhythm of the melody: a melody can race along in sixteenth notes over a single chord that lasts two bars, or move slowly while the chords change on every beat. Counting how long each chord lasts, rather than how many notes you hear, tells you the harmonic rhythm.

▶One chord per bar0:09▶Two chords per bar0:09

Slow and fast harmonic rhythm

A slow harmonic rhythm, one chord for a bar or more, sounds spacious and calm, or static and hypnotic when it lasts a long time. A fast harmonic rhythm, a new chord every beat or half bar, sounds busy, driven and full of direction. Hymns and chorales often change chord on nearly every beat; a lot of pop and dance music holds one chord for a bar or two; the basic twelve-bar blues changes chord no more than once a bar.

Speeding up toward the cadence

In much Classical music the harmonic rhythm speeds up as a phrase approaches its cadence. A phrase might hold one chord for a whole bar at first, then change twice per bar, then every beat just before the final V–I. That acceleration is part of what makes the cadence sound like an arrival.

Finding the harmonic rhythm

1. Listen to the bass: a new bass note on a strong beat often signals a new chord.
2. Notice when the melody's notes stop fitting the old chord.
3. Mark each change, then look at the pattern: once per bar, twice per bar, or something irregular.

Many Notes, Fewer Chord Changes and Mark the Chord Changes, Not Every Attack train exactly this skill.

Using it when you write

When you harmonize a melody, deciding how often to change chord is as important as deciding which chords to use. Too many changes can crowd a simple tune; too few can make it sound bare. Choosing chords for a melody walks through the decision.