Jarret has an unusual left thumb; it looks double-jointed. I’ve heard he “trained” his thumb to bend at the knuckle to make up for the fact that his hands were small and he had trouble playing tenths. Regardless, the “thumb hitting the fifth” can be a wonderful tool for a pianist in the practice room. It’s more than a metronome. It’s a way to test your ability to move in and out of different time signatures; you can solo behind or ahead of the pulse. It’s also a good way to test out your voicings, to hear how dissonant or consonant your voicings sound against the fifth, to see how well you can play your voicings without effort. It’s no coincidence that the fifth note happens to be the Mixolydian, the root of the “magic” dominant chord I discussed in last week’s post. The fifth can take you through the entire chorus of a tune. I’ve tried this with the F on “Someday My Prince Will Come,” the fifth of the B-flat major scale.
But the pulse note doesn’t have to be the fifth; you could use the root of that tune’s key, and you can of course switch the pulse note if, for example, the tune changes keys in the bridge. If you have trouble reaching tenths, if you can’t bend your thumb like Jarrett (I can’t), you can always “ghost” the note, leave a little space for it; if it’s been played for a few measures, the listener will hear it even though it isn’t actually played. The fifth note played in this way, as the pulse of your tune, is more than a metronome. It’s an opportunity to add beauty to your repertoire of ballads, a way to find unusual voicings you might not normally play, a way to create contrapuntal movement in your solos and comping, a way to stretch the melodic, harmonic, and rhythmic possibilities within a single tune.