: Hertz.</li>
  <li>[rad/pi] : Radian / π.</li>
  </ul>
  <h3 id="clangsynth-2"><a href="#clangsynth-2" class="header-anchor"
  aria-hidden="true">ClangSynth</a></h3>
  <h4 id="gain"><a href="#gain" class="header-anchor"
  aria-hidden="true">Gain</a></h4>
  <dl>
  <dt>Output [dB]</dt>
  <dd>
  <p>Output gain.</p>
  </dd>
  <dt>Attack [s]</dt>
  <dd>
  <p>Output gain smoothing time. Increasing <code>Attack</code> also
  increases release time.</p>
  <p>Note that the value is not exact. It converts to filter