Audacity is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems. Audacity won the SourceForge Community Choice Awards 2007 -- Multimedia Category ! Congratulations to the other finalists. Big thanks to SourceForge, to everyone who voted, and to all who contribute to making Audacity great! This editor can record and play sounds and import and export WAV, AIFF, MP3, and OGG files. Edit your sounds using cut, copy, and paste features (with unlimited undo functionality), mix tracks, or apply effects to your recordings. The program also has a built-in amplitude-envelope editor, a customizable spectrogram mode, and a frequency-analysis window for audio-analysis applications.
The latest release of Audacity is 1.3.3 (beta), which contains numerous new features and capabilities beyond the 1.3.2 (beta) release. Because it is a work in progress and does not yet come with complete documentation or translations into foreign languages, it is recommended for more advanced users. See New Features in 1.3 for more information about the 1.3.x beta series.
For all users, Audacity 1.2.6 is a stable release, complete and fully documented. You can have both Audacity 1.2.6 and 1.3.3 installed simultaneously.

Other Features
Audacity is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems. You can use Audacity to:
Record live audio.
Convert tapes and records into digital recordings or CDs.
Edit Ogg Vorbis, MP3, and WAV sound files.
Cut, copy, splice, and mix sounds together.
Change the speed or pitch of a recording.
And more! See the complete list of features.