Sound files in PDF documents

I work with special needs students. When text to speech is used in a document mathematical formulas come out incorrectly. With Acrobat Pro I can embed a sound file that is the spoken formula so the student can hear and understand. In Libre office I can create a pdf file with text boxes, check boxes, radio buttons and everything works with text to speech (screen reader or WordQ, etc). Is there a way to embed a sound file?

The solution below does not help in this instance. Under exam conditions, connection to the internet is not allowed so a hyperlink to a sound file outside the computer would not be allowed. To have a separate sound file that is part of an unzipped package that gets put on the students computer makes life more difficult for the special needs student. I really need a way to embed the sound file inside the pdf… as can be done with Acrobat Pro.

Looks like someone has done something similar, but I have no idea if this will help you.