A in-depth look at diatonic progressions and the functions of chords.
You’ve seen the videos online: “play 200 songs with 4 chords”. Yes, a lot of the popular music we listen to is made up of 4-chord progressions (not 4 chord progressions, but a chord progression with 4 chords), and these progressions are diatonic. The term diatonic progression means that all of the chords in the progression are from the same key (A progression is like a sentence in music, usually made up of 4 chords or so).
In each major key we find seven different chords. This is because we have seven unique notes in the major scale, and we can build a chord on each note. These seven chords can be grouped into three categories, according to their function (what their job is in a progression). The three categories are: Tonic, Subdominant and Dominant.
Tonic- this is the chord that is “home”. There is minimal harmonic tension on this chord.
Subdominant- this chord feels like you’ve gone for a walk away from “home”. There is a medium level of tension on this chord. The reason we call this chord subdominant is because in western harmony it usually comes before the dominant chord, preparing us for the dominant.
Dominant- this chord is the feeling “I want to go home”. There is a high level of tension on this chord. This is the chord that wants to go back to the tonic, it leads us back there.
*A lot of folk music from different areas in the world doesn’t include the dominant sound. The tonic, subdominant, dominant structure is a western music thing.
Let’s look at each chord from the major scale. The I (1) chord is the home, so it is a tonic chord. The ii (2) chord is like a walk away from home, so it is subdominant. The iii (3) has many of the same notes that 1 has, so we consider it a tonic chord by function, but it does have a different sound and a bit more tension than 1. The IV (4) chord has many of the same notes as the 2 chord and it is also like a walk away from home, so it has a subdominant function. The V (5) is the chord that screams “I WANT TO GO HOME”, it is the dominant chord. The vi (6) has many of the same notes as 1, so it has a tonic function but with more tension than 1. The vii (7) has many of the same notes as the 5 chord, so it has a dominant function and really wants to go home.
Tonic: I, iii, vi
Subdominant: ii, IV
Dominant: V, vii
As an example, let’s look at the song “No Woman, No Cry” by Bob Marley:
Listen to the song and notice the moment when you feel like the chord and melody are at home or stable. You can also listen to the beginning of a new phrase or the end of a phrase, to figure out what the “home” sound/chord is. This song is in Db Major. Here is the Db Major scale:
Based on the scale, let’s group each chord in the diatonic progression into the three categories.
Db Maj- this is I, so it is a tonic chord
C dim- this is vii, so it is a dominant chord
Bb min- this is vi, so it is a tonic chord
Gb Maj- this is IV, so it is a subdominant chord
Db Maj- this is I, so it is a tonic chord
Ab7- this is V, so it is a dominant chord
Db Maj- this is I, so it is a tonic chord
Ab7- this is V, so it is a dominant chord
Jazz music is not considered diatonic because it moves around many different keys, most commonly through the use of the 2-5-1 progression. But because popular music stays in one key, a key change in the song has a huge powerful effect that songwriters usually include near the end of a song, for example after the bridge. Check out this Backstreet Boys key change at 2:31 , and this Celine Dion key change at 3:41.
That's it for this week. Go listen to and learn some diatonic progression songs.
If you have questions email me! tetyanahar@gmail.com
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