Try opening it in iTunes if you have it. Or try opening it with Soundapp. If you have niether, you could use Quicktime Player.

Download iTunes for Mac OS 9 here: http://docs.info.apple.com/article.html?artnum=120073

Download iTunes for Mac OS X here: http://docs.info.apple.com/article.html?artnum=120074

Download Soundapp here: http://www-cs-students.stanford.edu/...dApp/#download