Glossary

Continuous Controller (CC)

A type of MIDI message typically used for the expressive, realtime, control of synthesis parameters. The origin of these messages lies in the need to transmit over MIDI, information from controllers such as modulation wheel and pitch bender. Continuous Controller messages are a generalization of this idea, and are not necessarily associated with any particular type of controlling device.

Envelope Generator (EG)

A synthesizer module, typically (although not necessarily) used for shaping amplitude with respect to time. Envelope Generators typically allow input signal to be shaped into four different segments: attack, decay, sustain, and release. These are illustrated in Figure 13.

Digitally Controlled Oscillator (DCO)

The digital counterpart of the Voltage Controlled Oscillator (VCO), commonly found on digital synthesizers. Unlike the VCO, the waveform produced is in the form of a sequence of numbers (hence digital) which are later converted to an electrical signal using a Digital to Analog Converter (DAC).

Frequency Modulation (FM)

A synthesis method brought into popular usage with the Yamaha DX7, a synthesizer which took advantage of technology developed at CCRMA by John Chowning. Essentially, Frequency Modulation is a form of vibrato which is so fast that pitch modulations become smeared into the audio spectrum, resulting in additional partials, known as sidebands.

Low Frequency Oscillator (LFO)

An oscillator used for modulating synthesis parameters at the note and/or phrase level. On the Oberhiem OB-Mx, for example, the LFOs offer a choice of 4 possible waveforms, and can be assigned to practically any synthesis parameter. Their speeds can be adjusted within the range: 0.1 to 30.0 Hz.

Low Pass Filter (LPF)

A filter which attenuates high frequency content of an input signal, while allowing low frequency components to pass through unimpeded. A High Pass Filter (HPF) does the opposite.

MIDI

Acronym standing for Musical Instrument Digital Interface. MIDI is the standard protocol used by electronic instrument manufacturers to enable one device to communicate with another.

Radio Baton

A device developed by Max Mathews for controlling electronic musical instruments via MIDI. The position in 3-dimensional space of (up to) 2 batons are tracked with the aid of radio technology housed in a separate processing unit.

Voltage Controlled Filter (VCF)

A module commonly found on analog synthesizers, which alters the spectral content of its input - for example, increasing the brightness of a tone. Usual control parameters include: frequency (or cut-off frequency), which adjusts the center-point of the filter; and resonance, which adjusts the width of the filter.

Voltage Controlled Oscillator (VCO)

A module commonly found on analog synthesizers, producing periodic waveforms in the form of a continuously varying electrical signal, which are used as the basis of sound synthesis. Typically, these waveforms have rich spectral content, and before final output, are filtered (further modifying the spectral content), and enveloped (shaping the amplitude of the waveform with respect to time).

Notes on the CD

The accompanying CD¹⁰ features a recording of Cosmos made on the occasion of its premiere at the CCRMA Summer concert, which took place on July 24, 1997, at the Knoll courtyard on the Stanford University campus.