Many audio recorders (such as the Olympus voice recorders at UWB) record in a compressed file type and will need to be converted to .wav before they can be opened in an audio editing program like Pro Tools or Audacity. Once you have finished your project, you will be exporting as a .wav file. You can then convert the .wav to a compressed file type like .mp3. These programs will allow you to convert your audio files from one file type to another.

From .wma or .mp3 to .wav:

PC

I downloaded and tried winLAME. Seems to work great. Open source and safe (no viruses). Works as a plug-in to Audacity as well.
http://winlame.sourceforge.net/

MAC

Several students have recommended Switch. They say it works great!
http://www.nch.com.au/switch/
MAC or PC

MPEG Stream Clip is in the DML and is a free program that you can download on your own computer. Fairly straightforward program.
http://www.squared5.com/

From .wav to .mp3:

MAC or PC

Many people use I-Tunes for converting from .wav to .mp3

Online conversion programs:

This website allows you to convert most audio file types in either direction – no download and it seems to work great!
http://media.io/