The “Switched-On Bach” Story

Moog’s Guide to Electronic Music Terminology

Unalphabetically Arranged in Logical Order

Electronic Music consists of electronically generated sounds and natural sounds that are modified electronically, assembled into music by magnetic tape manipulation, or performed live. Electronic music is a medium of expression, not a specific type of music. In fact, electronic music includes music as diverse as Carlos and Folkman’s Switched-On Bach, the newest Coca-Cola commercial, much of the currently popular rock ‘n’ roll, and representative material from all camps of the musical avant-garde.

WAVE FORM – The graph of an electrical variation versus time.

SIGNAL – The variations of an electrical current which constitute the flow of information.

GENERATOR – An instrument that originates a signal.

OSCILLATOR – A generator that produces periodic or regularly repeating wave forms. Oscillators produce pitched sounds.

TRANSIENT GENERATOR – A generator that produces a wave form of defined, but non-repetitive, shape.

RANDOM GENERATOR (also called WHITE SOUND SOURCE or WHITE NOISE GENERATOR) – A generator that produces a signal in which there is no predictable relation between any two parts of the wave form. The sound is completely pitchless and sounds like rushing air.

MODIFIER – An instrument that alters a signal in a specified manner. Modifiers are extremely useful for altering the tone quality of sounds.

AMPLIFIER – A modifier that alters the amplitude or intensity of a signal.

FILTER – A modifier that emphasizes certain frequencies and attenuates others. A LOW PASS FlLTER allows through all frequencies below its “cutoff frequency,” and attenuates all frequencies above cutoff; a HIGH PASS FILTER allows through all frequencies above its cutoff frequency, and attenuates all frequencies below cutoff. A BAND PASS FILTER passes one particular band of frequencies. An EQUALIZER is a filter that is generally designed to correct for non-uniform frequency response.

MODULATOR – A modifier that alters a given characteristic of one signal in response to the variations of a second signal.

REVERBERATION UNIT – A modifier that adds a series of closely spaced echoes to a signal, thereby imparting a sense of liveliness and space to sound material.

MIXER – An instrument which permits the controlled combination of signals and their routing to other instruments.

TAPE MUSIC – Electronic music that is assembled and composed by magnetic tape manipulation rather than by live performance.

MUSIQUE CONCRETE – Electronic music in which natural sounds, rather than electronically generated sounds, are used as source material.

VOLTAGE CONTROL – The control of the operating characteristics of an instrument by the variation of an externally applied voltage called the “control voltage.” A VOLTAGE-CONTROLLED OSCILLATOR is an oscillator in which the frequency of the wave form is voltage-controllable. A VOLTAGE-CONTROLLED FILTER and a VOLTAGE-CONTROLLED AMPLIFIER offer voltage-controllable cutoff frequency and gain respectively.

CONTROLLER – An instrument that produces one or more control voltages.

MANUAL CONTROLLER – A controller whose control voltage outputs respond to hand movements.

SEQUENTIAL CONTROLLER – A controller whose control voltage outputs consist of sequences of present (programed) voltages.

ENVELOPE – The loudness-time contour of a sound.

ENVELOPE GENERATOR or TRANSIENT GENERATOR – An instrument which produces a transient control voltage which, when used to control the gain of a voltage-controlled amplifier, imparts an envelope to a steady sound.

ENVELOPE FOLLOWER – An instrument which derives a voltage proportional to the envelope of the sound which is fed into it.

TRIGGER – A signal which has only two possiblc states and which is used to initiate transient wave form.

INTERFACE – An instrument that enables two other instruments of dissimilar modes of operation to function in combination.

SYNTHESIZER – A system of generators, modifiers, and controllers that is designed to permit the building-up of sounds in a general and logical way.

Considered as a live-performance medium, this means elimination of the tape recorder, first by increasing the instrument’s polyphonic capabilities, then by adding a small computer to control the synthesizer. This will not be the kind of computer now used to “compose” music, but a smaller unit storing instructions for the connections that must be made and broken instantly for every note.

Playing such an instrument will require a new kind of virtuosity, an intellectual command of what each of the synthesizer’s keys will “mean” from one part of the computer program to another – and perhaps some knowledge of mathematics, and the physics of why clarinets don’t sound like trumpets.

Even with these new controls, the synthesizer will for quite some time be far more of a composing than a performing instrument; its virtuosi will be, like Carlos, its composers, and vice versa. But that was also true of the piano in its earliest days.

Reprinted from “The “Switched-On Bach” story”, by Ivan Berger, 1969, Saturday Review, January 25 issue.