Electronic Music Interactive, 2nd edition

Glossary

time-variant control: to induce change in a generator or modifier module by means of a signal that varies over time. The changes induced by time-variant control will depend on what has been selected as the destination of the control signal.
time-variant controller: a module in the synthesis process which outputs a control signal that induces change analogous to the shape it outputs.
time and level: two values that provide the means by which each stage of an envelope is specified. The "time" value specifies the time it takes to move from its current level to the next specified level. The "level" value specifies the level achieved during the specified time.
triangle wave: a waveform that consists of odd-numbered harmonics, whose relative amplitudes are expressed by the ratio 1/harmonic number squared, and whose every other harmonic is 180 degrees out of phase.
ultrasonic: refers to frequencies that are higher than humans can hear, approximately 20 kHz and above.
variable: in recent synthesis systems, a number that is entered to specify a value for some parameter.
waveform: a graphic depiction of sound which shows the fluctuation of air pressure, voltages, or digital values over time.
waveform memory: the location in a digital synthesis system where a single cycle of waveform is stored. Oscillators in a digital system may access this memory, and by repeating this single cycle over and over, the oscillator is able to produce a continuously sounding waveform.
waveform selection: a control associated with oscillators that permits the user to define the waveform output within the limits of the system.
white noise: a common type of noise consisting of all audible frequencies of equal amplitude randomly distributed between any equal bandwidths.