How to Use Repetition When Playing Acoustic Blues Guitar
Although blues guitar is usually heard on electric guitar, it started out as an acoustic style. An important aspect of acoustic blues (and electric, too) is repetition. This idea involves a motive (a short musical phrase) that you repeat, sometimes once, sometimes over and over. In acoustic blues, you can achieve this effect in one of the following two ways:
Repeat a phrase at the same pitch as the background chord changes. Note that the chord changes from E to A. (The different bass notes that the thumb plays imply the chord change.) The motive, however, repeats at the same pitch. Notice how the same notes sound different if you play them against a different chord (even an implied one). This technique is a blues staple.
Repeat a phrase at a different pitch as the background chord changes. If you use this technique, the relationship between the melody and background chord stays the same. Barre the fifth fret to play the A chord in the second measure.
Notice that, for each chord, you use a hammer-on to move from the minor third to the major third. This technique is common in the acoustic blues style.