That reminded me of Sonic Pi: http://sonic-pi.net/ You can find some examples on the site and some videos of author Sam Aaron playing it as well. For those into Clojure, Sam is one of the instructors of LambdaNext.eu and one of the authors of Overtone, a Clojure synthesizer.

And I just found out that lambdanext.eu is down. I wonder if they stopped business, their last tweet (https://twitter.com/lambdanext) is a retweet when they gave a course in Brazil (btw, I'm the one using a Kendo hoodie). They're good instructors.