Programmable MIDI Instrument Controller Design: The No Strings Attached Hammer Dulcimer

Abstract

Real-time digital music system design often involves the translation of formal music notation or human gestures by some input device to Musical Instrument Digital Interface (MIDI) commands which are then transmitted to an electronic music synthesizer. This thesis describes the design and implementation of a microprocessor controlled input device that maps analog signals to MIDI commands and transmits them to a digital synthesizer in real time. The controller emulates a traditional acoustic folk instrument known as a hammer dulcimer.

The hammer dulcimer is the forerunner of the keyboard family of instruments and incorporates features found in percussive and keyboard instruments. As with any acoustic instrument, its tone is a composite of several partial tones. The controller, in emulation mode, generates the fundamental tone and optionally outputs the partials tones with the just noticeable difference (JND) tolerances described in psychoacoustic research. This feature allows the designer to experiment with the timbre of the fundamental tome. The controller interface succeeds in capturing the gestural movements and translating these events to MIDI commands. It also provides features such as on-demand retuning which allows the musician to play in any tonal center without changing hand positions. Selected MIDI features such as the pitch bend, program change and sustain are implemented by the controller. The prototype instrument yields a tow octave range from an eight by eight inch sensor grid. Additional grids can be added to increase the range of the instrument.