Lesson 26: Diatonic Function Analysis
This lesson teaches how to
understand the diatonic chords in "real"
songs.
Before taking this lesson, you should know: the
diatonic chord functions
(
Lesson 25: Subdominant & Dominant).
To learn to
use the diatonic chord functions (
tonic,
subdominant, and
dominant), you should study them in real songs.
This is called
diatonic function analysis.
Let's do an example. Here's a short chord progression in the
key of
C major (it's actually a simplified phrase from Bob Dylan's
Like A
Rolling Stone):
First, add
Roman numeral symbols (from
Lesson 23: Using Diatonics):
| I | IIm | IIIm | IV | V | I |
| C | Dm |
Em | F |
G | C |
Next, we'll add
diatonic function symbols. We'll use these symbols:
| T | = Tonic |
| (T) | = "substitute" Tonic |
| SD | = Subdominant |
| D | = Dominant |
Here's the example with the diatonic functions added:
| Functions: |
T | SD | (T) | SD | D | T |
| Roman symbols: |
I | IIm | IIIm | IV | V | I |
| Actual chords: |
C | Dm | Em | F |
G | C |
Tension Levels
The diatonic functions have different
tension levels, which means how
at rest, or
not at rest, that function feels. Here are the
tension levels, from "highest tension" to lowest:
| D (Dominant): |
Highest tension; "really wants to" return to Tonic. |
| SD (Subdominant): |
Not at rest. Often used to move away from Tonic; often moves to
Dominant. |
| (T) (substitute Tonic): |
Feels "semi" at rest. |
| T (Tonic): |
Feels at rest. |
The way a chord progression moves among the tension levels creates that
progression's
tension story. Here's our example progression (C →
Dm → Em → F → G → C) again, displayed as a
tension-level graph so you can see the
tension story's shape:
|
C | Dm | Em |
F | G | C |
| D |
| | | | V | |
| SD |
| IIm | | IV | | |
| (T) |
| | IIIm | | | |
| T |
I | | | | | I |
Following the Roman symbols above from left to right, we can see that this
example's basic tension story is:
-
Starts at rest, on I
-
Climbs (with a bit of wandering) to high tension (the V)
-
Drops back to rest (the last I)
This particular story/shape is very, very common, but there are lots of
variations and alternatives. To develop a feel for the effects of different
tension stories, you should include diatonic function analysis when you're
analyzing songs (see
Lesson 2: Practicing Songwriting).
Make tension-level graphs for lots of different songs, make up tension stories
from the graphs, and decide for yourself what you think the musical effects of
different tension stories are.
Next:
