I don't have that book handy, but I would have done it more like this: :frequency (+ freq (* offset (- i 6) 0.03)) :partials '(1 1 5 .7 6 .7 7 .7 8 .7 9 .7 10 .7)) (arpeggio 0 10 65 0.5) There are people, in San Francisco anyway, who can listen to such sounds for hours. They send me CDs.