I don't know whether the built-in PDF viewer supports embedded files, but there is a mysterious "attachments" section of the sidebar. Is it listed there?

Thank you for your reply Jscher. How I wish I could make my computer look like yours! That paper clip is exactly the paper clip I am trying to install on my Firefox bar. That paperclip will open embedded mp3 files in PDF files. I don't know where to go to get this done. But thank you for the teaser! Its kind of funny if it weren't so frustrating!

What I did to show that panel was click the sidebar button at the left end of the PDF viewer toolbar. I don't have an example where there actually is attachment.

Thank you Jscher!

I was making this so much more complicated than it need be. I cannot thank you enough. The hours spent and the hair loss in trying to load the add-on when it was there all along is embarrassing.

Thank you sir!!