Development Flash ActionScript

package {
    import flash.display.Sprite;
    import flash.media.Sound;
    import flash.media.SoundChannel;
    import flash.net.URLRequest;
    import flash.events.Event;
    
    public class Main extends Sprite {
        private var _sound:Sound;
        private var _channel:SoundChannel;
        
        public function Main(  ) {
            addEventListener(Event.ENTER_FRAME, onEnterFrame);
            _sound = new Sound(new URLRequest("song.mp3"));
            _channel = _sound.play(  );
        }
        
        public function onEnterFrame(event:Event):void
        {
            var leftLevel:Number = _channel.leftPeak * 100;
            var rightLevel:Number = _channel.rightPeak * 100;
            trace(leftLevel);
            trace(rightLevel);
            
        }       
    }
}