The programs producers use are really expensive. I've checked out a few of the free programs (years ago) and they didn't seem to work. BuzzMachines was neat but the author lost the source code at one point and attempted to remake his program. There are a bunch of BuzzMachine FOSS clones. I believe one or more of those programs attempt to be binary compatible with BuzzMachines. Non-commercial software always has an advantage in novelty and yet it lacks quality. I've always wanted to try CSound which I hear compiles sounds much like a software compiler compiles a program. I guess SuperCollider does about the same thing? I bought the MIT Press Computer Sound Book Bundle by Humble Bundle earlier this year since sound programming is a project I know I'll attempt at some point.