depends on the highest and lowest levels.
        <code>CURVE</code> is ignored if <code>BASE</code> is non-NIL. The utility
        <code>ENVELOPE-BASE->CURVES</code> returns the list of curvature values for the
        :CURVE keyword related to an envelope's base in CLM style:
      </p>

      <pre class="src src-lisp"><span class="prompt">SCRATCH&gt;</span> (envelope-base->curves 10 '(0 1 .5 0))
(2.3025851 -0.597837 -1.704748)</pre>

      <p>
        If the envelope is sustained, the <code>:RELEASE-NOD