I figured, well, I can play it, so I can understand it. Right? WRONG! Ionian, Mixolydian, Dorian. I put the harmonica in my mouth and I end up playing in all these modes, but I can barely understand it and certainly couldn't explain it easily. It is a lot like Dan Grigor says. In the Pentatonic Blues you only use five notes, and they all sound good, so as long as you are in rhythm it doesn't matter what note you play. more »