Rhythm and harmony

There is a close relationship between chord progressions and rhythm.

By virtue of their functions in the tonal system, chords create a dynamic with supports, tensions and expectations. The perception of the same meter can vary depending on the chord progression. A simple meter making use of unvaried rhythmic patterns can be very effective and sound very rich depending on how it is supported by the harmony.

Here are the main chord functions according to the position they occupy in the scale:

Example in C major
  • I
  • II
  • (III)
  • IV
  • V
  • VI
  • (VII)

Tonic and dominant chords:

I chord (tonic chord)

Chord whose root is the first scale degree (tonic).

The tonic triad is the tonality’s identity card. It is a resolution chord and a rest chord.

V chord (dominant chord)

Chord whose root is the fifth scale degree (dominant).

When composed of four notes, it is called a dominant seventh chord. It acts as a tension chord, and its tension resolves on the tonic chord.

Supertonic, subdominant and submediant chords:

II chord (supertonic chord)

Chord whose root is the second scale degree (supertonic).

When this chord is placed before the V chord, it mitigates the V chord’s tension.

IV chord (subdominant chord)

Chord whose root is the fourth scale degree (subdominant).

When this chord is placed before the V chord, it enhances the V chord’s tension.

VI chord (submediant chord)

Chord whose root is the sixth scale degree (submediant).

When this chord is placed after the V chord, it eludes the V chord’s tension.

Thanks to the functions of the chords, musical phrases are built melodically and rhythmically. Cadences are predefined chord progressions which help punctuate them. Rhythms built on cadences are closely related to this punctuation.

Cadence Function
Perfect cadence
II (ou IV) • V • I
 It concludes and ends a phrase, just like the period.
Half cadence
Rest on V
 It represents a suspension in the phrase, like the comma.
Plagal cadence
IV • I
 It can replace the perfect cadence, and can represent the semicolon.
Deceptive cadence
V • VI
 It creates an expectation, not unlike ellipses.