Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
Bosca Ceoil - A free, easy to use tool for creating music.
Spek - Spek helps to analyse your audio files by showing their spectrogram.
Renoise - Renoise is a digital audio workstation.
SoX - Sound eXchange is a command line utility that can convert various formats of computer audio files...
Zynewave Podium - Podium is a modern digital audio workstation (DAW) for Windows.