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Glossary
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ADSR
Acronym for Attack, Decay, Sustain, Release. Describes the four stages of a standard envelope generator.
AES/EBU
Digital audio standard developed jointly by the Audio Engineering Society (AES) and the European Broadcast Union (EBU). The standard describes a format for transmitting stereo digital audio along a serial cable. Although balanced XLR is the only "official" cabling format, fiber optic and coaxial cables commonly are used.
AFTERTOUCH
MIDI message that indicates the amount of pressure applied to a key, or keys, after they have been depressed.
ALGORITHM
A pattern of information or set of instructions. In electronic music, an algorithm can define the specific set of parameter values to create a sound on a synthesizer, or specific permutations of MIDI data performed by computer software.
AMPLIFIER
A device or software algorithm that increases the amplitude of the voltage, power, or current of a signal.
AUTOMATION
The act of controlling aspects of a music studio automatically. For example, mixer automation allows you to record the movement of the volume faders or mute switches so that they will consistently repeat their movements.
BALANCED/UNBALANCED
Terms used to describe two types audio cable conventions. Unbalanced cables, such as standard guitar cords, use two wires. One wire carries the actual audio signal and the other is used for ground. Balanced cables, such as three-pill XLR microphone cables, use two wires for the signal and one for the ground. One of the signal wires carries the sound while the other carries an inverted copy. When the sidnal reaches the destination the inverted copy is flipped and added to the original. Any noise added by the wire also is inverted. When combined with the "non-inverted" noise, the two noise signals cancel each other out.
BPM (Beats Per Minute)
A measure of tempo in music. A rate of 60 bpm means that one beat will occur every second.
BYTE
A piece of digital information. Much like each word is a piece of an English sentence, a series of bytes typically makes up digital messages. In MIDI, bytes are made up of eight bits, and most messages are two or three bytes in length.
CLICK TRACK
Audio "clicks" recorded on one track of a multitrack tape recorder. The clicks indicate the tempo of the music on the tape. These clicks help musicians play with the recorded music, or they can be translated into MIDI sync.
COMPRESSOR (compression)
A compressor is an amplifier whose output decreases as its input increases. It squashes the dynamic range. Threshold defines the level at which the compressor kicks in. Ratio defines how many dB the output will decrease for each dB that the input increases above the threshold. Attack determines how fast the compressor will react to a signal that exceeds the threshold. Release determines how long it takes for the compressor to return to full output once the signal has dropped below the threshold.
CONTINUOUS CONTROLLERS
A set of MIDI messages, such as Modulation Wheel and Volume, that represent dynamic or continuously changing aspects of a performance. These are the primary means of communicating musical expression with MIDI.
CONTROL VOLTAGE
Electrical signal used to control the values of parameters in analog circuits. By sending a specific (or continuously varying) electrical voltage to an element of the synthesizer, such as a filter, you could describe what you wanted it to do (such as raise or lower the cutoff frequency).
CUE
A section of music or sound effects used in a film or video. A cue can range from a short piece of background music to a complex score. The specific points at which the cues are triggered in order to correspond to visual events are called cue points or "hit" points.
CUTOFF FREQUENCY
The point at which a filter no longer allows frequencies and overtones of a sound to pass. In a lowpass filter, a high cutoff frequency allows most of a sound through and generally produces a bright sound, while a low cutoff frequency blocks most of the sound and produces a muted or plain sound.
DAT
Acronym for Digital Audio Tape, a medium for storage of digital audio on small cassette-like tapes.
DB
Abbreviation for Decibel, a logarithmic expression of a ratio comparing two quantities, such as how much louder one sound is than another, or how much more power is available at the output of an amplifier than at the input. Also used to indicate the amplitude of a signal.
DIGITAL
In essence, having to do with numbers. In electronic music, digital information may describe the waveform of a sound or the nuances of a performance as a series of numbers. The numbers then are translated back into sound or played as a performance on electronic instruments.
ENVELOPE GENERATOR
An electronic circuit or software algorithm that changes parameters over time. A sound's volume envelope will determine the different volume levels of a sound from the point it is first played until it is no longer heard. A filter envelope similarly will determine the changing brightness of a sound over time.
EPROM/EEPROM
An acronym for Erasable Programmable Read Only Memory. This is a type of computer chip that can loaded with digital information (perhaps a sample of a sound) and later erased and loaded with new information. Standard EPROMs are erased under exposure to ultra-violet light. A newer version, EEPROM (Electrically Erasable Programmable Read Only Memory), can be erased by an electrical voltage, making the chips much easier to update.
FILTER
A device that removes, or "filters" certain elements or data from an audio waveform or datastream. In a synthesizer, a lowpass filter allows low frequencies to get through while inhibiting higher frequencies; a highpass filter does just the opposite. A bandpass filter allows the frequencies within a specified range to pass, while a notch filter blocks the frequencies in a specified range. A MIDI data filter removes certain messages from the MIDI datastream.
FSK
Acronym for Frequency Shift Key. FSK is an audio tone typically generated by a sequencer, drum machine, or computer MIDI interface that is recorded on one track of an audio tape for synchronization purposes. The tone alternates between two frequencies, and the rate of alternation indicates the tempo of the music being used as a reference. FSK can be used to synchronize MIDI sequencers and drum machines to tape machines.
HERTZ (Hz)
The measure of a frequency of a vibrating object, such as a guitar string or speaker cone. Equivalent to cycles per second. The human range of frequency perception is about 20Hz to 20,000Hz (or 20 kilohertz, abbreviated kHz).
MASTER
Term used to indicate the controlling instrument in a system. If the MIDI Out of synth A is connected to the MIDI In of synth B, synth A is the "master" and synth B the "slave".
MIDI
Acronym for Musical Instrument Digital Interface. A digital communications protocol developed in the early 1980s that allows electronic musical instruments and computers to communicate with each others. The protocol consists of a set of messages that represent various aspects of a musical performance.
MIDI CHANNEL
A logical division separating MIDI messages, which allows multiple instruments to be addressed independently over a single MIDI cable. Most messges are sent on one of sixteen channels Instruments can be set to respond to specific channels, allowing them to play certian parts and ignore others.
MIDI CLOCKS
Also known as "MIDI Sync". A set of messges that communicate tempo and timing information between instruments in a MIDI system.
MIDI INTERFACE
A hardware device that connects to a personal computer and translates MIDI into a format it can understand.
MIDI MODE
An operational state that determines how an instrument will respond to incoming MIDI messages. In Omni mode, an instrument responds to notes on all channels. In Poly mode, the instrument plays multiple notes simultaneously. In Mono mode, the instrument plays only one note at a time.
MIDI TIME CODE (MTC)
A set of MIDI synchronization messages that correspond to SMPTE time code. MTC allows MIDI software to synchronize more easily with time code recorded on film or video tape.
