code: function(angle) {
      this.dir = (this.dir + angle + circle) % circle;
  
      // Calculate the rotation vector and update the orientation of the listener.
      var x = Math.cos(this.dir);
      var y = 0;
      var z = Math.sin(this.dir);
      Howler.orientation(x, y, z, 0, 1, 0);
    }
docs: Rotate the player's viewing direction.
  @param  {Number} angle Angle to rotate by.