In the below code sometimes when microphone is not connected some noise is generated and the system just keeps on buzzing the same sound.Whats wrong with the code below and how to reduce the unwanted noise. Should i set myMic.setLoopBack(false) in the below code

<?xml version="1.0" encoding="utf-8"?>
<mx:Application
xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute"
width="300"
height="100"
creationComplete="init()">

<mx:Script>
  <![CDATA[
     import mx.controls.Alert;
     import flash.net.NetStream;

     private var myMic:Microphone;
     private var recordingState:String = "idle";

     private function init():void {

        myMic = Microphone.getMicrophone();
        myMic.setSilenceLevel(0);
        myMic.rate = 44;
        myMic.gain = 100;
        myMic.setUseEchoSuppression(true);
        micLevel.visible = true;
        //Security.showSettings(SecurityPanel.MICROPHONE);
        myMic.setLoopBack(true);
        if (myMic != null)
        {
           myMic.setUseEchoSuppression(true);
           micLevel.setProgress(myMic.activityLevel, 100);
           addEventListener(Event.ENTER_FRAME, showMicLevel);
           //micLevel.setProgress(myMic.activityLevel, 100);
        }

     }

     private function showMicLevel(event:Event):void{
        switch (recordingState){
           case "idle" :
              micLevel.setProgress(myMic.activityLevel, 100);
              break;
        }

       }







  ]]>
  </mx:Script>

    <mx:ProgressBar x="0" y="36" mode="manual" id="micLevel" label="" labelPlacement="bottom" width="100" fontSize="10" fontWeight="normal"/>


  </mx:Application>