Classic Computer Magazine Archive COMPUTE! ISSUE 165 / JUNE 1994 / PAGE 63

PC sound glossary. (Compute's Getting Started With: PC Sound)
by David English

ADC. Short for Analog to Digital Converter. A circuit that converts an analog audio signal into a digital audio signal. See also analog, digital, and DAC.

analog. An audio signal whose fluctuating voltage pattern reflects the structure of the original sound. See also digital.

CD-DA. Short for Compact Disc-Digital Audio. Also known as Red Book audio. The CD-quality audio that comes directly from a conventional audio CD or CD-ROM. See also track.

DAC. Short for Digital to

Analog Converter. A circuit that converts a digital audio signal into an analog audio signal. See also ADC, analog, and digital.

dB. Short for decibel. The standard unit of measurement used to describe a sound's amplitude or loudness. An amplitude increase of 1 dB results in a sound that's ten times louder.

digital. An audio signal that has been converted into numbers that no longer directly reflect the structure of the original sound. See also analog.

DSP. Short for Digital Signal Processor. An integrated circuit designed for high-speed data manipulation. Many sound cards use a DSP to provide reverb, 3-D, voice recognition, and other special audio effects.

dynamic range. The difference between the loudest and softest sounds for a particular product or situation.

General MIDI. An extension of MIDI that establishes a set of 128 instrument sounds that are grouped in a standard order. See also MIDI.

Hz. Short for Hertz. Also known as cycles per second. A unit used to measure the frequency of a vibrating object, such as a violin string or the cone in a speaker. The human ear can hear from approximately 20 Hz to 20 kHz (20 to 20,000 Hz).

kHz. Short for Kilohertz. Unit of frequency measurement that denotes 1000 waves, or cycles, per second. See also Hz.

MIDI. Short for Musical Instrument Digital Interface. Pronounced "middy." A digital communications protocol that allows electronic musical instruments and computers to communicate with each other. Because MIDI sends performance information (such as note on, note off, pitch change, and volume) rather than actual musical sounds, it's a highly efficient way to store and transmit musical data.

MIDI connector. A five-pin DIN plug used to connect MIDI devices.

MIDI file. A file format for storing MIDI songs. MIDI files generally have the extension MID on the PC.

MIDI interface. A serial hardware device that allows a computer to send and receive MIDI data.

MIDI Mapper. A Windows Control Panel applet that lets you specify which MIDI device will be associated with each of MIDI's 16 channels, which sound will be associated with each of Windows' 128 MIDI instruments, and which MIDI note will be associated with each MIDI drum sound.

MIDI software. A computer program that can record, play, or manipulate MIDI data.

MPC. Short for Multimedia PC. Any computer, upgrade product, or software title that conforms to the standards set by the Multimedia PC Marketing Council.

multitrack. A device or software program that offers more than two tracks for information storage. See also track.

Red Book audio. See CD-DA.

sample. To record digitally using an ADC. See also ADC.

sampling rate. The frequency with which an ADC scans an incoming electrical signal. Higher sampling rates provide higher-quality recordings but require more storage capacity. Professional DAT (Digital Audio Tape) recorders use a sampling rate of 48 kHz, audio CDs use a sampling rate of 44.1 kHz, consumer DAT recorders use a sampling rate of 32 kHz, and many broadcasters and multimedia developers use a sampling rate of 22.05 kHz. See also ADC, kHz, and sample.

sound card. Also known as sound board. An expansion board you place inside a PC that improves the quality of the PC's sound output. A program must support the sound board before it can benefit from the board's improved sound quality.

synthesizer. An electronic musical instrument that can generate simple or complex sounds. Most synthesizers include a MIDI interface and a keyboard, though synthesizers without a built-in keyboard (called sound modules or expanders) are becoming increasingly more common.

tempo. The speed that a MIDI file plays in MIDI software. Tempo is generally measured in beats per minute (BPM).

track. A song or sequence of sound on a CD-DA disc. When referring to a MIDI file, a track can be an individual MIDI channel or a separate part of a MIDI song. See also multitrack.

WAVE file. The standard Windows file format for storing waveform audio. WAVE files generally have a WAV extension.

waveform audio. A technique for re-creating voice and sound effects using digital audio samples. Under Windows, waveform audio is generally stored with the WAV file-name extension.