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Sensors and Synthesis
Musical instruments such as the piano allow musicians to play in different keys on a single instrument. In contrast, bamboo flutes are designed for only one key. This means flute players must own a different flute for every additional key in which they want to play in. Learn how these three Cornell students built an PIC32 MCU-based electronic flute that reduces the need for owning multiple flutes by incorporating two buttons that allow a flute player to change the key and octave.

Our goal for this project was to build an electronic flute that can play in any key. The first step in this project was understanding the design of a bamboo flute, which differs greatly from Western concert flutes. A typical bamboo flute can be played in only one key. It has a total of seven holes, six of which are used to play different notes. The seventh hole is for the inlet of wind (the player’s breath). The strength of air blown into it determines the octave of the note.

If the strength of the air blown exceeds a certain threshold, the flute produces sound in a higher octave. Otherwise, the flute produces sound in a lower octave. The arrangement of the player’s fingers over the six holes distinguishes the different notes. Whether a hole is open, half-covered or fully covered by a finger also differentiates the note being played. For example, if a fully covered hole generates a note C major key, the half-covered hole generates a note in C minor key.

PHYSICAL/HARDWARE DESIGN
Our electronic flute, shown in Figure 1, is built to be comparable in size, design and spectral dynamics to a typical bamboo flute. We simulated the six finger holes of a typical flute using capacitive touch sensors. A seventh hole holds the microphone and simulates a flute’s blow hole. Physically, these switches are pieces of copper tape connected to wires. We used a total of 13 capacitive touch sensors—two for each hole and one for the “chin sensor.” The chin sensor determines when someone is playing the flute. It is positioned directly under the microphone hole, and needs to be touched when playing. The microphone detects if air is blown into the flute, indicating that a sound should be produced. Note that the words button, switch and sensor used throughout this article functionally refer the same general mechanism.”

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