Hi Jonathan, hi Jay,
Jonathan: you need to add notes an octave lower than your voice: just
replace 1+ with 1- in the Scheme code.
Jay: actually, your code has one major downside: is doesn't handle
\relative mode very well. As soon as you add a comma or a single quote
to one of the pitches in the melody, the octaves go crazy.
Perhaps this is only a problem of ordering the elements in the
octavize-chord function, but I suspect it's worse than that.
It works very well in absolute pitches mode, though.
Cheers,
Valentin