Sounds in AS3

I see how to play an external sound file in AS3:

var soundClip:Sound;

function init() {
soundClip = new Sound();
soundClip.load(new URLRequest(“NameOfSong.mp3”));
soundClip.addEventListener(Event.COMPLETE, soundLoaded);
soundClip.addEventListener(ProgressEvent.PROGRESS, soundLoading);

function soundLoaded(e:Event) {;

function soundLoading(e:ProgressEvent) {
// preloader information goes here

If I click on a button that goes to and plays another label or goes to and stop sat a certain frame, how do I stop the first sound file and begin to play a second?