title: Controlling volume in Sonic Pi
body: <p>I'm trying to code a polyphonic song in Sonic Pi, and I really need to be able to control the volume. I've looked through the Sonic Pi tutorials and found nothing. Please help.</p>
  
  <p>Specifically, I've tried using [play :A4, amp: 3.0] and fiddling with the amplitude, but for some reason it doesn't work. Below is a code snippet of a sequence of two-note chords:</p>
  
  <pre><code>play :E3, release: 0.5, amp: 3.0
  play :A4, release: 0.5, amp: 3.0
  sleep 0.2
  play :E3, release: 0.5, amp: 1.0
  play :E3, release: 0.5, amp: 1.0
  sleep 0.2
  play :D3, release: 0.25, amp: 2.0
  play :E3, release: 0.25, amp: 2.0
  sleep 0.2
  play :Fs3, release: 0.5
  play :Gs4, release: 0.5
  </code></pre>
  
  <p>but the volume just isn't changing. What am I doing wrong?</p>