Not sure if this is what you are after, but the Head First Java book has a "beatbox" application as a substantive project throughout the book, and it has dowloadable code.
You may want to check this out, the code is downloadable at
Head First Download, the Appendix A download has the BeatBox
teacher/educator and a one idea java programmer - first go about 10 years ago looked promising and attracted angel funding, pulled out because code was too crufty, now having a second part time go being poorer yet the wiser.
Writes R script in day job :-(