                            (oscil md)))))))))
</pre>
-->

<!-- SND CASE -->
<pre class="indented">
(define* (fm beg dur freq amp mc-ratio index (index-env '(0 1 100 1)))
  (let* ((start (seconds-&gt;samples beg))
         (end (+ start (seconds-&gt;samples dur)))
         (cr (make-oscil freq))
         (md (make-oscil (* freq mc-ratio)))
         (fm-index (hz-&gt;radians (* index mc-ratio freq)))
         (ampf (make-env index-env :scaler amp :duration dur)) 
         (indf (make-env index-env :scaler fm