A Percusive sensor for playing a computer-controlled synthesizer
M. V. Mathews, J. Kohut · The Journal of the Acoustical Society of America · 1985
A sensor is described for performing a computer-controlled synthesizer. The sensor consists of an equilateral triangle-shaped surface, which is struck with a soft drumstick. Each time the sensor is hit, it sends four pieces of information to the computer—a trigger pulse, the two coordinates of the strike point, and the force of the blow. This information is used by the computer program to control the synthesizer. Several modes of control have been tried. In all modes, loudness is controlled by blow force. In one mode, the two coordinates control pitch and decay time of the sound. Another mode is a form of “conductor program” in which the sequence of pitches to be played is stored in the computer memory. Each stroke causes the next pitch in the sequence to be played. The two coordinates control decay time and spectrum of the sound. The sensor uses three strain gauges mounted at the corners of the triangle. The coordinates and force are computed from the strain gauge outputs by a simple analog circuit.