Snd is a sound editor modelled loosely after Emacs. It can be customized and extended using eitherΒ s7Β (included in the Snd sources),Β Ruby, orΒ Forth. Snd is free; the code is available via anonymous FTP as Snd tarball.

ccrma.stanford.edu/software/snd/
ccrma.stanford.edu/software/snd/snd/snd
sourceforge.net/projects/snd
