Audacity Audacity is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux, and other operating systems.

Features:
- Record from microphone, line input, or other sources.
- Dub over existing tracks to create multi-track recordings.
- Record up to 16 channels at once (requires multi-channel hardware).
- Level meters can monitor volume levels before, during, and after 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 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.
- Note: Audacity does not currently support WMA, AAC, or most other proprietary or restricted file formats.
- Easy editing with Cut, Copy, Paste, and Delete.
- Use unlimited Undo (and Redo) to go back any number of steps.
- Very fast editing of large files.
- Edit and mix an unlimited number of tracks.
- Use the Drawing tool to alter individual sample points.
- Fade the volume up or down smoothly with the Envelope tool.
- Change the pitch without altering the tempo, or vice-versa.
- Remove static, hiss, hum, or other constant background noises.
- Alter frequencies with Equalization, FFT Filter, and Bass Boost effects.
- Adjust volumes with Compressor, Amplify, and Normalize effects.
- Other built-in effects
- Record and edit 16-bit, 24-bit, and 32-bit (floating point) samples.
- Record at up to 96 KHz.
- Sample rates and formats are converted using high-quality resampling and dithering.
- Mix tracks with different sample rates or formats, and Audacity will convert them automatically in realtime.
- Add new effects with LADSPA plugins.
- Audacity includes some sample plugins by Steve Harris.
- Load VST plugins for Windows and Mac, with the optional VST Enabler.
- Write new effects with the built-in Nyquist programming language.
- Spectrogram mode for visualizing frequencies.
- “Plot Spectrum” command for detailed frequency analysis.