Nyquist
Nyquist is a sound synthesis and composition language offering a Lisp syntax as well as an imperative language syntax and a powerful integrated development environment. Nyquist is an elegant and powerful system based on functional programming. You can download pre-compiled version (v3.06) here.

Audacity® is free, open source software for recording and editing sounds. It is available for Mac OS X, Microsoft Windows, GNU/Linux, and other operating systems. Audacity was originally designed and developed by Roger Dannenberg and Dominic Mazzoni working in Carnegie Mellon’s School of Computer Science Computer Music Project.