Audacity is a free audio editor. You can record sounds, play sounds, import and export WAV, AIFF, and MP3 files, and more. Use it to edit your sounds using Cut, Copy and Paste (with unlimited Undo), mix tracks together, or apply effects to your recordings. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications. Built-in effects include Bass Boost, Wahwah, and Noise Removal, and it also supports VST plug-in effects.
What's new in version 2.4.2
Easy configuration reset: A new command has been added to the Tools menu: Tools > Reset Configuration. This resets your Audacity configuration, preferences, export settings and toolbars, to default settings.
MP3 exports and imports without padding: Audacity now supports LAME's gapless playback info, allowing MP3s to be exported and imported without additional padding.
Other applications that support the LAME tag, for example audio player applications, will be able to read MP3 files exported by Audacity without the padding.