Sound object parent reference

I’m creating a bunch of movieclips, associating a sound object with them, and then updating them with a progress bar, like so:

var theClip:MovieClip = new MovieClip;
theClip.track = new Sound;

[load sound from URL pseudocode here]

theClip.track.addEventListener (ProgressEvent.PROGRESS, onLoadProgress);
function onLoadProgress (e:ProgressEvent):void { [some reference???]

How do I reference the movieClip the sound is a child of? refers to the sound object; returns an error. And you can’t assign properties to sound objects.