\version "2.18.0"

randomNotes =
{
  $@(let ((notes (ly:music-property #{ <e f g a b c' d' e' f' g' a' b' c'
d'> #}
                                    'elements)))
      (map (lambda (x) (list-ref notes (random (length notes)))) (iota
400)))
}

\new Voice {
  \transpose c c {
    \randomNotes
  }
}