Variable scope

Hello the one thing I do not get is variable scope. Below is some fully functional code.

Where I have the  comment  ( // public or private ?)  is what I do not get.

I tried to change to change var to public var or to private var on both of those lines

of code and each time I get errors. So what exactly is the scope since you cannot specify

public or private as a prefix to either line?

package {
    import flash.display.Sprite;
    import flash.events.*;
    import flash.media.Microphone;
    import flash.system.Security;
    import flash.system.SecurityPanel;

    public class MicrophoneExample extends Sprite {
        public function MicrophoneExample() {
            var mic:Microphone = Microphone.getMicrophone();  // public or private ?
            Security.showSettings(SecurityPanel.MICROPHONE);
            mic.setLoopBack(true);
                   
            if (mic != null) {
                mic.setUseEchoSuppression(true);
                mic.addEventListener(ActivityEvent.ACTIVITY, activityHandler);
                mic.addEventListener(StatusEvent.STATUS, statusHandler);
            }
        }

        private function activityHandler(event:ActivityEvent):void {
            trace("activityHandler: " + event);
            var str:String="Test";  // public or private ?
            trace(str);
        }

        private function statusHandler(event:StatusEvent):void {
            trace("statusHandler: " + event);
        }
    }
}

Thamks,

Jim