From the site:
"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."
Download Audacity (for Mac or Linux)