My first experiment with real-time digital signal processing using Arduino, this is an edit of "Somewhere Over the Rainbow" that I made using a handmade vocal effects box. This effects box uses an Arduino to sample incoming audio at 40kHz with 8 bit precision, the audio data is then digitally pitch shifted and distorted to produce a wide variety of effects. To minimize the amount of computation required by the Arduino, I used a technique called granular synthesis to perform the audio processing. Essentially, as audio comes into the Arduino it gets cut up and stored as small (millisecond or microsecond sized) samples called "grains." These grains are then individually manipulated and played back; they may be lengthened or shortened, stretched or compressed, played back in reverse, copied several times, or mixed with other grains. This project was inspired largely by the music of Fever Ray. Find out how to build your own on Instructables.
Download it here (rt click, save as).