Audio Editor FREE is a straightforward tool for processing MP3, WMA, WAV and OGG music files.
If you've ever used another audio editor then you'll be familiar with the basic approach taken here. You open your audio file, it's displayed as a waveform, and you can select particular areas with the mouse to zoom in. And it's then possible to delete those sections, or apply one of a host of effects or filters (Amplify, Chorus, Echo, Fade, Flanger, Mix Stereo Channels, Normalize, Reverb, Band Pass, Low Pass, High Pass, Low Shelf, High Shelf, Peak EQ and more).
What's more, clicking the Tools button reveals several bonus extras: a CD ripper and writer, file format converter, MP3 tag editor and more.
All isn't quite as it seems, though. The core editing interface is oddly designed, no menus, non-standard buttons, it just doesn't work as you expect and we didn't find it at all comfortable to use.
And it turns out that many of those bonus tools don't provide any useful functionality unless you spend $9.95 to upgrade to the Premium edition. (The free batch file format converter will only save files in WAV format, for instance - you need to buy the Premium edition if you want to export to MP3.)
There is still a lot of free audio editing power here, though, and if you just want to work on your MP3 files, say, Audio Editor FREE will probably do a reasonable job. But you may have to spend a while mastering the program's oddities before you're fully productive with it.