Watch the Altering Dominant Chords online guitar lesson by Jason Loughlin from Focus On: Western Swing
The dominant chords can be an amusement park for harmonic wackiness. Let's look at two ways to create an altered sound on our dominant chord. One is to use the whole tone scale. This is a scale in which each tone is separated by a whole step. I'll show you two fingerings for this scale. By playing it over a dominant chord you're accessing the root, 9, 3rd, #11, #5 and b7. The other scale we'll look at is the diminished scale. The formula for this scale is alternating half and whole steps. By playing this over the dominant chord you're accessing the root, b9, #9, 3, #11, 5,13, b7. Once we've discussed how to use the scale we'll experiment with the whole tone and diminished arpeggios over dominant chords.