Magpie MIDI Is a Harmonica-Like Adaptive Interface

Mouth-based assistive input devices are often able to sense “sips” and “puffs” of air, for two button-like inputs. This is, of course, makes text entry cumbersome at best. Other forms of expression, like the ability to play music or video games are subject to the same sort of limitations. In order to help overcome these restrictions, Shu Takahashi and Pato Montalvo came up with the Magpie MIDI adaptive interface that has 13 breath channels, based in part on a hands-free harmonica unit.

The 13 air passages provides access to all 26 letters in the English alphabet, with sips for one half and puffs for the other. Additionally, the "harmonica" base is set up as a joystick, enabling directional input for a cursor with a potentiometer implemented to detect it being rolled from side-to-side.

This joystick setup allows for cursor input on a computing device, or the controls could also be used for gaming. As implied by its name, the Magpie MIDI can also act as a musical controller, where the sips and puffs trigger notes, and the potentiometer/joystick modify the sound output.

Takahashi and Montalvo's prototype runs on an Arduino Leonardo, using a CD74HC4067 multiplexer chip to handle all the inputs. More info on the project’s progress is available here, while an overview of its functionality can be seen in the video below.