I don't mind the singing at all, infact i sing right
along with him alot of the time. i sing/hum while i
play the piano too, especially when i am learning a
piece and trying to get the different thematic lines
in my head. I was taught this way, that if you can
sing the melody, or countertheme or whatever (even if
off key) then you will be able to play it, because it
is "in your ear". it's true, at least for me.
This was good advice. Organists learning to play hymns for congregational singing are taught to sing the alto, tenor and bass parts as they play.
Some of the recordings don't have much humming. Seems to be something missing on them.
James