Loading successive swfs

My grey matter is burned out at this point of the day, so the solution to the following is probably obvious.

I have a loader which is supposed to load a number of .swfs, loading the next one when the last one is completed. I have the following:

var ldr:Loader = new Loader();
var c:int = 0;
var clips:Array = new Array("dmt1.swf","dmt2.swf","dmt3.swf","dmt4.swf")
ldr.load(new URLRequest(clips[0]));
addEventListener(Event.ENTER_FRAME, loading);
function loading(e:Event){
 if((MovieClip(ldr.content) != null)&&(c < 4)){
  if(MovieClip(ldr.content).currentFrame == MovieClip(ldr.content).totalFrames){
   c ++;
   ldr.load(new URLRequest(clips[c]));

This works… to a degree. The second swf, for example, loads when the first swf is finished, but you can hear the audio from the first swf replaying while the second swf’s audio is playing. What am I doing wrong here??

Many thanks.