Play music loop throughout the course

In my previous project I have been asked to have continuous loop music (with soft and lower volume) along with onscreen narrations. Another condition was, this loop should not be reloaded while moving to next-previous or any other slide through menu. That time I was unable to do this but now I have succeeded in doing this.

All I've done is added couple of lines of code in story.html file and placed my loop music in output folder. See working demo here.

Code I've added is:

<audio style="position:absolute; top:0px; left:0px; opacity:0;" controls preload autoplay loop>
<source src="loop.mp3" type="audio/mpeg">

</audio>

Just before closing body tag. However, this thing is working only in chrome. I am trying to make it work on IE too. If any body knows another method please share.