As part of an experiment with real-time digital signal processing and an Arduino, Amanda Ghassaei has created a device that pitch shifts and distorts incoming audio signals to produce a wide variety of vocal effects. By sampling incoming sound, splitting it into tiny data elements then modiftying them the resulting sound is quite different - therefore having the ability to make various sound effects. This technique is called "granular synthesis". The audio output is generated by a typical R/2R resistor ladder and op-amps; and the whole kaboodle fits in this enclosure:
If you're interested in experimenting with sounds and Arduino, but don't have much time or budget - consider our SOUND: sound and buzzer module:
It can be used as a noise-maker driven by your microcontroller for audible feedback of events, and it can also be used as a knock-detector input to sense events and react to them. Includes a built-in 1M resistor to allow the piezo element to detect shocks. For more information and to order, please visit the product page here.