How to get an XML gauge to play sounds?

Hi all,
I'm trying to write a gauge in XML to play .wav files as cabin announcements - but having no luck so far. Anybody out there give me a steer on how to tell the gauge that it needs to play a sound file?
Thanks,
Martyn
I'm trying to write a gauge in XML to play .wav files as cabin announcements - but having no luck so far. Anybody out there give me a steer on how to tell the gauge that it needs to play a sound file?
Thanks,
Martyn