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.
* Import and export WAV, AIFF, AU, and Ogg Vorbis files.
* Import MPEG audio (including MP2 and MP3 files) with libmad.
* Export MP3s with the optional LAME MP3 encoder library.
* Create WAV or AIFF files suitable for burning to CD.
* Import and export all file formats supported by libsndfile.
* Open raw (headerless) audio files using the “Import Raw” command.

It supports all common editing operations, plus it will mix tracks and let you apply plug-in effects to any part of a sound. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications.