Try this technique to record your audio (the settings tools will test your audio is OK).
PowerPoint Narration – YouTube Don’t link the narration file – it needs to be embedded.
(Radio quality is fine.)
If you are using Windows 2010 and later it is possible to export your narrated presentation as a video: Microsoft Guide
Once you have a .wmv file this can be uploaded through MyMedia
If you have followed the guidance, but continue to have problems with your audio, please visit the IT Help Desk.