Zach Poff is a Digital Media Artist, Educator, and Maker of Things. On his website he has some great resources including some DIY projects (I have used his info on the Alex Rice Piezo Preamplifier before). Zach has a couple of interesting pieces of software, including a Soundscape Composer which looks cool, but I haven’t used, and a little app called Pitch Playground, which is a good way of demonstrating how sound waves combine to create new frequencies by way of interference phenomena. For guitarists, think of the beating you hear as you tune the notes closer to each other, and that is an example of interference phenomena. Pitch Playground is free for Mac, and you can find out more or download from the link below: