(click me for a larger version)
Behold the first physical prototype of the Text Drum. I turned the practice pad in the lower right-hand corner of the photograph into a drum trigger by outfitting it with a piezo sensor (I followed these instructions, though I used the bottom of a can of Danish butter cookies instead of a disc of galvanized steel). The pad worked so well that I decided I needed a second sensor, so I glued a second piezo to the side of a block of wood I scavenged from the shop.
Both the pad and the block are connected to my Arduino, which sends data from the piezos (using code adapted from todbot's tutorial) over serial to the Semantic Anomalizer (pictured on the screen, in the process of mutating Pride and Prejudice).
Overall, I'm pleased: I'm getting reliable, well-timed readings from the drum triggers, and using them along with the software I've been prototyping was gratifying. As I mentioned above, playing with the prototype made it obvious that more than one trigger was needed; I programmed the second trigger (the wood block) to insert a line break into the text, which adds a few new expressive and structural possibilities.
Problems: I cut the foam inside of the practice pad kind of unevenly, and the metal that the piezo is attached to is kind of warped. As a result, the response of the trigger is kind of uneven over its surface. The trigger works reliably; it just doesn't give reliable data about how hard it has been hit. Right now, I don't need that data—I just want a digital trigger. But this is definitely an avenue for future improvement.
Also, I'm not sure how well my original idea for the interface will work—i.e., a mapping between your rhythmic accuracy and the amount of randomness in the order of the words that the program outputs. For the most part, I just enjoyed hitting stuff and making words come out. I'm not sure if subtly varying your timing is the best way to be expressive with this thing. More experimentation is needed.