Audacity is a free, easy-to-use audio editor and recorder for Windows, Mac OS X, GNU/Linux and other operating systems. Audacity can record live audio through a microphone or mixer, or digitize recordings from cassette tapes, records, or minidiscs. With some sound cards, Audacity can also capture streaming audio. And if you have sound files already on your computer but you would like to combine with other files or new recordings, you can import those files into your Audacity project. It is capable of importing sound files in many formats including WAV, AIFF, MP3, and OGG files.
As well as recording audio from multiple sources, Audacity also comes with a full set of editing features. You can use it to edit your sound files using Cut, Copy and Paste (with unlimited Undo), mix tracks together and apply effects to your recordings. Audacity also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications. Some of the built-in audio effects include Bass Boost, Wahwah, Equalization, Noise Removal and Normalize, Vocal Remover as well as support for VST plug-in effects.
Audacity is available for Windows, Mac OS X, GNU/Linux and other operating systems. You can download it for free from this link.