.MP3 and .Wav are audio file formats. Another is .ogg, which is much common but with many .mp3 players supporting it you are likely to encounter one when developing a presentation at some point.
Vorbis is the group behind the .ogg format and it is for the most part a higher quality file than an .mp3. The Ogg Vorbis is a fully open, non-proprietary, patent-and-royalty-free, general-purpose compressed audio format for mid to high quality audio and music. Here is what an “ogg” looks like:
Unfortunately PowerPoint does not support the .ogg format, so if someone sends one to you for a presentation you will need to convert it to another format (.mp3 or .wav) in an audio editing application.
-Troy @ TLC