Please follow the steps below to embed audio-
1) Open PowerPoint
2) Click on the insert tab of the ribbon and insert MP3 audio from, audio/sound from file option on the right
3) Download authorSTREAM Desktop - http://www.authorstream.com/desktop/ - a free PowerPoint plug-in for PowerPoint 2007/2010 (ribbon) to upload your presentation with linked audio (WAV, MP3 formats only) on authorSTREAM.
4) Now upload the file from within the PowerPoint using "Upload PowerPoint" button under authorSTREAM tab.