Pump organs were popularized in the late 1800s as a sort of a little cousin to the gigantic pipe setups that you’ll find in older churches and auditoriums. Roughly the size of a piano, they could be fit into a non-palatial home, while still producing a more limited range or organ sounds. In use, air is admitted to the pipes via stops, including one special stop called a “vox humana,” Latin for human voice. While this is supposed to sound like a singing human, it, according to Alec Smecher’s project write-up, just sounds like a pump organ stop.
Smecher, a software developer and musician, was tasked with converting one of these instruments into a device that speaks a numeric combination to a lock as a part of an escape room. He wired up all of the keys with switches, then used a matrix setup to supply this information to an Arduino Leonardo, chosen for its inherent HMI capabilities. In this case the Leonardo is impersonating a MIDI keyboard, which uses a computer to play the correct vocal tone depending on the keys pressed.
In order to generate voices for each key, he used a web app called Pink Trombone, which imitates human vocal chords graphically — and is quite entertaining for a quick distraction. He used the Web MIDI API found here for control, which would be an excellent tool for those looking to make music in an unusual way. Check out his demonstrations in the video below. The first, is a more traditional musical interface, while the second sounds eerily human.