Here is the HTML:
<audio controls="controls" tabindex="0">
<source type="audio/ogg" src="/Public/audio/ding.ogg"></source>
<source type="audio/mp3" src="/Public/audio/ding.mp3"></source>
Your browser does not support the audio element.
</audio>
The player displays just fine in the latest version of Chrome (18).
Whereas in Firefox 12, the player flashes on initial page load and just fades out.
Here's are the error messages I see when inspecting via Firebug:
HTTP "Content-Type" of "application/octet-stream" is not supported. Load of media >resource http://localhost:18214/Public/audio/ding.ogg failed.
Specified "type" of "audio/mp3" is not supported. Load of media resource /Public/audio/ding.mp3 failed.
All candidate resources failed to load. Media load paused.
How can I play an audio file in Firefox 12?