Progressions

A chord progression is a sequence of chords with the purpose of establishing a tonality founded on a key, root, or tonic chord.

Chord progressions ...

• seen vertically, provide the "harmony" needed to accompany a melody;
• seen horizontally, provide a sense of movement, a mood in the flow of time.

Chord progressions are abstractly described by Roman numerals, where each number is a degree in the scale.

Upcase Roman numerals are used for major chords, and lowcase for minor chords.

Some common progressions:

The choice of chord alterations in a progression depend on the compatibility of chords for the scale being used.

So the first step is to determine which chords are compatible with the chosen scale.

For the following example, we will use the Major (Ionian) scale.

Mapping each note in the scale to a degree, initially yields:

Building triads for each degree, using only the notes of the scale, gives:

This helps us further refine the previous table, to include the nature of each chord (major/minor/augmented/diminished) .

This produces an initial "palette" of compatible chords to work with this scale.

Continuing this way, we can produce a more complete chord compatibility chart for the Major (Ionian) scale.

This gives a wider "palette" of chord alterations to choose from.

Which chord alterations to choose, depends on the melody, and on the mood you want to project.

The next step is to produce a chord progression.

There are several approaches to building chord progressions:

• One approach is progressing by 4ths or 5ths, which is equivalent to using the "circle of fifths".
• This approach is most often used, and produces the strongest sense of tonality, and contrast, since there is always one note in common between each successive chord.

• In this example, we take C as the starting point and tonality, next we leap forward to A, and then take successive counter-clockwise steps back to "home" (C).
• This produces the I-vi-ii-V-I progression, one instance of which could be: C6, Am7, Dm7, G7, C (choosing alterations from the chord compatibility table).
• Another approach is to progress by 3rds or 6ths.
• This creates a sense of continuity, because there are always two notes in common between chords.

• In this example, we take C, the tonic as the starting point, jump forward to Dm, and then take successive counter-clockwise steps back to home.
• This produces the I-ii-IV-vi-I progression: C, Dm, F, Am, C.
• Yet another approach is to progress by 2nds.
• This approach has no notes in common, there is less sense of continuity.