We aren’t sure this technically qualifies as music synthesis, but what else do you call a computer playing music? In this case, the computer is a Teensy, and the music comes from a common classroom instrument: a plastic recorder. The mistaken “flute” label comes from the original project. The contraption uses solenoids to operate 3D printed “fingers” and an air pump — this is much easier with a recorder since (unlike a flute) it just needs reasonable air pressure to generate sound.
A Teensy 3.2 programmed using the Teensyduino IDE drives the solenoids. The board reads MIDI command sent over USB from a PC and translates them into the commands for this excellent driver board. It connects TIP31C transistors, along with flyback diodes, to the solenoids via a terminal strip.
On the PC, a program called Ableton sends the MIDI messages to the Teensy. MIDI message have three parts: one sets the message type and channel, another sets the velocity, and one sets the pitch. The code here only looks at the pitch.
This is one of those projects that would be a lot harder without a 3D printer. There are other ways to actuate the finger holes, but being able to make an exact-fitting bracket is very useful. Alas, we couldn’t find a video demo. If you know of one, please drop the link in the comments below.