Adding audio comments to Acrobat can be done by directly recording the audio in Acrobat or adding a pre-recorded file. Take these steps to add audio comments to PDF in Acrobat Reader.

3. Take Charge of Comments If your documents are reviewed by a group of people, you’ll appreciate Acrobat’s ability to add comments to PDF files.

Pick Save as PDF to choose a filename and destination, and you can even add password protection to the document if you want to. There's PDF functionality built right into Finder as well.

Can a free PDF editor meet your needs? Find out which of Adobe's PDF editing tools is the perfect version for you.

PDF Barber is a free website with tools for simple PDF edits like splitting files, re-ordering pages, and adding signatures. I like this website for a couple reasons.