How to Play the 12 Bars of Blues on the Harmonica

By Winslow Yerxa

The harmonica is well-suited for the blues. One of the most well-loved (and basic) song forms used in blues and rock is called 12-bar blues, which is like the verse of a song. This verse form is the container for both melodies and solos, and when you understand its features, you can easily find things to play within it.

The “bar” in 12-bar is just a group of two, three, or four beats (usually four), with an emphasis on the first beat. The 12-bar blues has — you guessed it — 12 of these bars. What’s inside those bars? It could be any one of hundreds of different melodies, or thousands of different solos, all identifiable as 12-bar blues to anyone familiar with the form.

So what gives 12-bar blues its distinct identity if it isn’t melody? Keep reading to find out.

Making a statement: Tell it, brother!

A verse of 12-bar blues has three main parts, and you make a statement in each of those parts. The first two statements move from one to the next in a way that feels compelling and flows into a resounding third, final statement.

Here’s a 12-bar blues divided into its three parts. Each part is four bars long, and each bar has four beats, represented by diagonal slashes. The chords are written above the slashes as Roman numerals.

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Each part of the verse is defined by its place in the chord progression. Consider the following:

  • The first part of the verse is called the I because it starts on the I chord. In the simplest version of 12-bar blues, the I chord lasts for four bars. You make your initial statement in the I part.

    Sometimes the IV chord is played in the second measure, going back to the I chord for the third and fourth measures. This little taste of the IV chord has various names: it’s called an early IV, a quick change, or a split change.

  • The second part of the verse is called the IV. It starts with the IV chord, which lasts for two bars, followed by the I chord, which comes back for two more bars. In the IV part, you can repeat your initial statement or make a new statement that elaborates on the first one.

  • The third part of the verse is where you deliver the final summation that answers the first two statements and prepare for the next verse. The third part is the busiest part of the verse. It has two components:

    • The come-down: The come-down introduces the V chord. The V chord is played for one measure, and then it comes down to the IV chord for one measure.

    • The turnaround: The turnaround lands back on the I chord. In a simple blues tune, the last two bars of the tune may play nothing but the I chord. However, often the turnaround goes through a quick sequence of I-IV-I-chords that ends on the V chord.

Listen to hear the chord changes narrated as a 12-bar blues plays in the background.

Fitting the notes to the chords

Melodies always give a prominent place to the notes that make up the background chord. You spend more time on the chord notes than other notes, and you often play chord notes on the first and third beats, which get the strongest emphasis. Knowing which notes on the harmonica correspond with which chord in any song (including the 12-bar progression) gives you a launching pad for everything you play.