diff --git a/opal/browser/audio/node.rb b/opal/browser/audio/node.rb
index 8a0c7fe..7d9326c 100644
--- a/opal/browser/audio/node.rb
+++ b/opal/browser/audio/node.rb
@@ -71,6 +71,10 @@ def type=(type)
   def type
     `#@native.type`
   end
+
+  def when_finished(&block)
+    `#@native.onended = block()`
+  end
 end
 
 class Delay < Base