Oh Jesus, we have to deal with IE again and now its mobile version.
There are 2 major causes for IE mobile and HTML5 standard audio not working.

First : the file

At the moment IE only supports mp3 for html5 audio

Check out w3schools

Second: “raise suspance…… drums…. AUDIO FILES HOSTED ON HTTPS FAILS!”

Error: Audio playblack was aborted

Exactly, IE10 Mobile at the moment could not play audio files (standard html or from javascript) via https!
Sweet!
Just put those files on an http (if you can) and rejoice.
Geez.