For me audio is automatically stopped; perhaps you could provide a .hype and .iba file that reproduces it continuing to be played?
Regardless, I would expect this technique could be used to pause the audio. Step one would be to create a custom behavior that has actions to pause your audio. Then you’d probably modify pauseAudioVisual block to look like this to run the custom behavior:
widget.pauseAudioVisual = function() {
HYPE.documents[DocumentName].triggerCustomBehaviorNamed("customBehaviorName");
};