want to change the "temperament" by changing the fundamental frequency of the notes. Is it possible to do this?
It sounds like you'd rather have an overall host application feature, but quite a few current soft-synths feature Scala implementation. Dimension Pro, Rapture, z3ta+, Rhino, VSampler, Eve, Tobybear's Helios, and Cameleon come to mind. You can take advantage of the 3000+ .scl files available in the archive [
here].
More importantly, you can get as creative as you want by creating your own custom files. There's a full-featured open application on a variety of platforms that's very deep and extensible:
Scala 2.2t here. For more information, go to
Scala's home page [here].