Edit Audio track with Audacity
Audacity is a free and open source multi-track audio editor and recorder for Microsoft Windows, Mac OS X, GNU/Linux and other operating systems. Audacity supports MP3, MP2, WAV, AIFF, AU, FLAC, AC3, M4A/M4R (AAC) and WMA and Ogg formats. Audacity features include envelope editing, mixing, built-in effects, plug-ins and all with unlimited undo.
Download Audacity from http://audacity.sourceforge.net