Play Harmonies on a Single Trumpet

Using a Capacitive Touch Slider, Raspberry Pi 4, and Arduino Uno

- By Robert Haig and Henry Geller

While many instruments such as the piano or similarly organized mallet percussion instruments have the capability to play in harmony, brass instruments do not. These Cornell University students created the Trumpet Harmonizer, a pitch shifter that enables musicians to harmonize with themselves in real time. With the touch of a finger, the musician can turn solo music into a duet, which provides endless possibilities for creativity and music transformation.

While many instruments such as the piano or similarly organized mallet percussion instruments (xylophone) and string instruments that are played with a bow (violin, cello) or plucked or strummed (guitar, banjo) have the capability to play in harmony, brass instruments do not The mechanics of our device, the “Trumpet Harmonizer,” make it as easy as possible for a musician to add harmony to playing a brass instrument— in our case, a trumpet—and to dynamically control that harmony.

A capacitive touch slider is mounted to the side of a trumpet, so that a musician can control the interval at which the harmonizer pitch-shifts the sound. The touch slider is placed vertically in front of the valves (Figure 1), so that players can easily use their right thumb, which typically doesn’t have a function when playing the trumpet, to control the harmony interval, while they press the valves. This extra control will take practice for a musician to master, but once familiarity with the technique has been acquired, the additional motion does not interfere with the ability to otherwise play the instrument, and is intuitive for the player.

A microphone attached to the bell of the trumpet captures the sound it produces, and the audio is processed and pitch-shifted based on the interval selected on the touch slider. The pitch-shifted notes are played on speakers in real time so that the harmony effect is created.

MUSIC THEORY