I tried it out.
I created a page with an html5 audio player:
<!DOCTYPE html>
<html>
<head>
<meta content="text/html; charset=UTF-8" http-equiv="content-type">
<title>test html5 audio</title>
</head>
<body>
<p>Hier kommt ein mp3 hin:</p>
<audio controls="controls">
<source src="juba%20juba.mp3" type="audio/mpeg">
<source src="juba%20juba.ogg" type="audio/ogg">
</audio>
</body>
</html>
BG did no harm to this (apart from the abyssmal source formatting). I loaded it up and it played well in Firefox, Chrome. No IE8 of course (have to because still XP) and no Opera.
Opera played locally fine, though. so its definitely a wrong server declaration.
Tried out .htaccess (idea from
http://html5doctor.com/native-audio-in-the-browser/)
AddType audio/ogg .ogg
but to no avail.
Anyway, it's not a BG problem this time!