dt>Smoothing [s]</dt>
  <dd>
  <p>Parameter smoothing time.</p>
  <p>Note that the value is not exact. It converts to filter cutoff
  frequency.</p>
  </dd>
  </dl>
  <h4 id="oscillator"><a href="#oscillator" class="header-anchor"
  aria-hidden="true">Oscillator</a></h4>
  <dl>
  <dt>Impulse [dB]</dt>
  <dd>
  <p>Gain of impulse which is triggered at note-on.</p>
  <p>Impulse can be used as a spice for cymbal sound. Also, impulse is
  not affected by velocity, so it can be used to control intensity of
  imp