package {
    import flash.display.Sprite;
    import flash.events.ActivityEvent;
    import flash.media.Microphone;

    public class ActivityEventExample extends Sprite {
        public function ActivityEventExample() {
            var mic:Microphone = Microphone.getMicrophone();
            mic.addEventListener(ActivityEvent.ACTIVITY, activityHandler);
        }

        private function activityHandler(event:ActivityEvent):void {
            trace("event: " + event);
            trace("event.activating: " + event.activating);
        }
    }
}