Because the Arduino is in such high demand for producing multiple musical tones at the same time; [Jeremy Blum] has successfully figured out the math and other necessaries that will take your once previously single tone producing MCU and turn it into a 5 tone producing machine. unsurprisingly its really just some creative use of PWM control but it all works out in the end anyway and helps prevent you from purchasing additional sound generating chips. This truly does open up some new doors, as [Jeremy] shows with his still in production thingamakit like project: ReacXion.