Coursera has renamed their free Introduction to Music Technology course to ++ Technology of Music Production ++

To take the course for free you have to select AUDIT.

This course lasts six weeks and began yesterday (July 25).

Sorry for replying on this so late but I think the reason they did that was they split the original Modern Musician Specialization to 2 new ones, Music Production Specialization and Developing Your Musician Specialization.

I'm still finishing the old specialization and may work on the Music Production Specialization since it has a couple of extra classes that look interesting.

Also, there's a cool, newer Berklee class below that focuses on changing and creating new synth sounds:

Creating Synthesizer Sounds for Electronic Music

I am going to set aside some time for that. Thank you.