声音触发事件

import flash.media.Microphone;
import flash.events.ActivityEvent;

var mic:Microphone;
var _on:Boolean=false;

stage.align=StageAlign.TOP_LEFT ;
stage.scaleMode=StageScaleMode.NO_SCALE;

mic=Microphone.getMicrophone();
mic.setLoopBack();
mic.setSilenceLevel(25,500);
mic.addEventListener(ActivityEvent.ACTIVITY,onActiv);
update();

 function onActiv(event:ActivityEvent):void{
 if(event.activating){
  _on=!_on;
  update();
 }
}

function update():void{
 graphics.clear();
 if(_on){
  graphics.beginFill(0xffffff);
  
  
 }else{
  graphics.beginFill(0);
 }
 
 graphics.drawRect(0,0,stage.stageWidth,stage.stageHeight);
}