The CVS guile has the new ratio code; see guile-devel: http://mail.gnu.org/archive/html/guile-devel/2003-11/msg00094.html for the announcement. If you need help getting the CVS Guile to build, let me know -- on my machine I always have to fix one ifdef by hand (involving argz.h or something like that). Also, I actually haven't tried this version of Guile yet, so there may be incompatibilities with Snd.