12 Bar Blues Overview
12 bar blues started out as a combination of European popular songs, African rhythm and tonality which developed in cotton fields. The format always followed a "Call and Response" pattern where one singer would call out a verse and the other singers would respond to that verse.
Each verse of blues is first called and then answered. Each call and response takes up either two or four bars. For example:
"From dawn to dusk I work the fields all day ....
Yeah, from dawn to dusk I work the fields all day ....
But when the sun is down I rush home to sweet Mae."
The chords are standard European style popular music chords arranged in a simple way. By 1920 the Blues was usually based on the popular 12 bar blues. It was differentiated from the typical tin pan alley popular music of the times by dark tonal qualities which were the result of mixing major, minor and 7th chords with the music. Popular American music was heavy Major chords which were "On the Beat" whereas "race music" or blues was delay time, syncopated music that had different chords.
The chords are numbered with Roman Numerals: I, IV and V ( that's 1, 4 and 5) these chords are also called the Tonic, Subdominant and the Dominant.
In the key of C the the I chord is C; the IV chord is F (count up 4 C-1, D-2, E-3,F-4) and the V chord is one more than the IV or G.
Pop-Quiz: What are the I, IV and V chords for the key of G?
Answer: G,C and D.
Blues uses these three chords in a simple pattern called 12 bar blues. A bar in blues is 4 beats. So a 12 bar blues is 48 beats long.
The 12 Bar Blues pattern is:
You stay in the I chord for 4 bars and then switch up to the IV chord for a couple of bars. Your ear doesn't want to be in the IV chord and seems to want you to return to the I chord. The IV chord is thought of as creating tension and coming back to the I brings resolution.
You stay in the I for two bars and then create new tension by jumping up to the V chord for one bar. The V chord is very up tight and you want to get back to the I, so you play the V and then try the IV each for one bar and then drop back to the I chord. You can't rest there (unless its the end of the song) and you go back up to the V chord which will create the motion to get you to "turnaround" to the beginning of the 12 bar blues sequence. That little ending piece which brings you to the V and back to the beginning is always referred to as a Turnaround.
How does this work on the harp? Well the draw holes on a C harp is the G chord. We place cross harp to get better access to certain notes so on a C harp we play in the key of G. (Count up 4 from G and you get C: G-1,A-2,B-3,C-4. After G you start over again with A).
The Draw notes are the I chord. The Blow notes are the C chord which as we know is the IV chord. What is the V chord? Well there isn't a V chord on the harmonica so we have to use the just the V note which is 1 hole draw or the 4 hole draw. (This note is D, but that is too much information for me - All I need to know is that it is the V note.)
So playing 12 bar blues is easy. Place you mouth over the bottom three or four holes on the harp and: (each draw and blow should have 4 beats to it.)
Draw - Draw - Draw - Draw
Blow - Blow - Draw - Draw
Switch your mouth to the bottom (number 1) hole.
Draw - Blow
now Draw on the bottom 3 or 4 notes and then:
Draw the 1 hole.
You are now a bluesman. You can actually go to the jams and play a little in the background using this. Soloing is harder, but this "close enough' style of the blues sounds great as accompaniment for an acoustic guitarist.