Have you tried something based on the pagehide/pageshow event?
I have used them for tab switching and it works also for when you hit the home button.
<audio src="pathto.mp3" controls id="audioTag"></audio>
<script type="text/javascript">
window.addEventListener('pagehide', function(){
document.getElementById('audioTag').pause();
alert('pagehide');
}, false);
window.addEventListener('pageshow', function(){
document.getElementById('audioTag').play();
alert('pageshow');
}, false);
</script>