code: function() {
      var self = this;
  
      // Get the Howl we want to manipulate.
      var sound = self.playlist[self.index].howl;
  
      // Puase the sound.
      sound.pause();
  
      // Show the play button.
      playBtn.style.display = 'block';
      pauseBtn.style.display = 'none';
    }
docs: Pause the currently playing track.