PDF files may contain audio, but generally they are text and graphics. There are not programs to translate the text to audio. You could ask Reader to Read the pdf and record it by capturing the audio output. But that is a kludge.
you're wrong. this can be done.
I've looked at Omar Mefire's (http://omefire.blogspot.com) solution and it seems to do what I want.
He's working on a service that takes a PDF file, and converts it to audio (.wav and .mp3) .
drop him a mail if you are interested.
here is email : firstname.lastname@example.org