audacity

GUI editor for digital audio waveforms

Audacity is a program that lets you manipulate digital audio waveforms. In addition to letting you record sounds directly from within the program, it imports many sound file formats, including WAV, AIFF, AU, IRCAM, MP3, and Ogg Vorbis. It supports all common editing operations such as Cut, Copy, and Paste, plus it will mix tracks and let you apply plug-in effects to any part of a sound. It also has a built-in amplitude envelope editor, a customizable spectrogram mode and a frequency analysis window for audio analysis applications.