Audacity

Audacity is a freeware audio files editor, a free alternative for programs such as Cool Edit Pro and WaveLab. Its main objective is to record and play sounds, import and export files in MP3, WAV, AIFF, Ogg Vorbis and other formats.

Audacity allows editing of audio tracks using cutting, copying and pasting (along with free-form undoing the performed operations), mixing tracks and adding effects (echo, noise removal, normalization etc.) as well as using VST and LADSPA effect plug-ins. It also includes an enveloping curve/amplitude editor, spectrogram and frequency analysis display regulated module for audio analysis programs.