Audacity is a free audio editor. You can record sounds, play sounds, import and export WAV, AIFF, Ogg Vorbis, 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 Echo, Change Tempo, and Noise Removal, and it also supports VST and LADSPA plug-in effects.

Changes in Audacity 1.3.7 beta :

• Cross-platform Bug Fixes:
- Muting/soloing caused incorrect channel results in exported stereo files
- Noise Removal and all Nyquist effects pasted the original unmodified audio at the end of the modified region
- Noise Removal inserted a tail of low level noise at the end of the modified region
- Nyquist and Compressor plug-ins did not display moving bars in progress dialogue and over-estimated "Remaining Time"
- Cancelling Nyquist effects deleted unprocessed audio
- Change Speed and Change Tempo failed to modify the original selection length
- Cut lines invisible
- Fixed various bugs importing multi-stream files via FFmpeg
- File > Export as WAV could be corrupted if overwriting an imported WAV read direct from the file
- Export multiple "Other uncompressed files" choice always produced 16-bit PCM audio irrespective of chosen options.
- MP3 export usually produced a 128 kbps constant bit rate file irrespective of chosen options; reported length often incorrect
- MP3 ID3 Genre tag misread on import if the genre list in Metadata Editor was opened and saved
- Exported metadata tags in MP3, OGG and FLAC often not seen by player software - now substantially improved
- WMA exports (via FFmpeg)corrupted if metadata tags included
- Some multi-channel recording devices that previously recorded more than two channels no longer did so
- Generated audio did not fit in window
- No warning was given when saving an empty project
- Beep on completing longer process did not work on many systems
- fixed crashes importing lists of files (.LOF), in Meter Toolbar and Change Speed
• Platform-specific Bug Fixes:
- Windows Vista: crash opening Preferences with no sound devices enabled and connected
• New Features:
- F11 Full Screen mode
- High-quality "Sliding Time Scale/Pitch Shift" effect
- Audio Contrast Analyzer for testing audio on the internet for WCAG2 accessibility compliance.
- Windows: sound devices can now be opened using the more efficient DirectSound API
• Other changes:
- Latency correction should be improved for many users by employing a fixed rather than variable correction
- Grouping of Effects into categories turned off until a way is added for users to do so themselves
- Numerous minor interface improvements such as Metadata Editor navigation, new "hh:mm:ss + hundredths" selection format
- Note: Windows users wanting to export MP3 files will require the latest version of the LAME encoder from http://lame.buanzo .com.ar/

Changes in Audacity 1.2.6 :

- Fix memory leaks on Windows.
- Correct font size problems.
- Enable missing FLAC support.