What is your left thumb good for?

If someone asks me to critique their church music improvisation, there are certain things I tend to watch for.  One of them happens to be what they to do with their left thumb.  Here is why.

Too often, church pianists have been taught to play octaves in their left hand.  The reason is that in normal congregational accompaniment (hymnplaying), the piano is relied upon to provide a solid sound.  So pianists are taught to play octaves in both hands, normally filling in the octave in the right hand with other chord tones. 

While this is OK in some settings, you should normally avoid playing octaves in the left hand because doing so unnaturally emphasize the root of the chord.  If you want to double any note, it should probably be the melody note.

If you are playing loud sections or songs, go ahead and play your octaves in the left hand and big chords in the right hand.  But for all other occasions, don’t let your left thumb take the easy route by doubling the root.  You simply are not going to get a smooth gentle sound if you do.

So what should you play instead?  I like to play 10ths, 7ths, 6ths, and 5ths in the left hand.  If you can play a 10th, you need to learn how to effectively use it because it will dramatically improve your sound.

Playing a 7th in the left hand is known as a shell voicing and I can’t tell you how often I use it.  Just play the root and the 7th (either major or minor) rather than the octave.

Moving your left thumb off the octave to one of these other notes will greatly help you by allowing you to spread out the notes and create open voicings.  For example, if you play the 7th with the left thumb, that will allow you to avoid playing it in the normally more crowded right hand voicing.

Besides opening up the voicing, it also creates an opportunity for the right hand to fill in an extra note to further color the chord.  If you play the 3rd (10th) in the left hand, the right hand does not have to.  It could for example, play a 9th instead.

Also, watch the left thumb on arpeggios.  Very often, pianists play short little arpeggios in the left hand and manage to double the root at least once (normally with the thumb).  I don’t know why this is so common but I see it quite often.  If you find yourself playing 1 – 5 – 1 arpeggios, try 1 – 5 – 3 instead.  For example, if you are playing a C chord as an arpeggio in the left hand, don’t play C – G – C.  Play C – G – E.

Here is the takeaway.  Don’t waste the note played by your left thumb by doubling the root.  Use it to open up the voicing and free up the right hand to potentially add a color note to the chord.