A signal that is modulated by some other signal, as in FM synthesis.

Constant BitRate Encoding, the more commonly used method that allocates the same number of bits per second of audio throughout the entire track.

Consultative Committee on International Telephone and Telegraph.

CD audio
Short for "Compact Disc - Audio"; current standard for stereo music CDs: 44.1 kHz sampling rate and 16-bit word width.

A huge online database of audio CD information including album, artist, song names and more.


Short for "CD-Recordable"; The term describes a blank CD. It is placed in a CD-R recorder to burn digital data onto the CD (cannot be deleted/overwritten).

Compact disc read-only memory. A compact disc format that can store data other than just standard CD audio. Many programs, sound sample libraries, and graphics are distributed on CD-ROM because each CD can store hundreds of megabytes of information. > ROM.

CD-R Recorder
Also called "CD burner" or "toaster"; device used to burn data onto CD-Rs, can also usually be used as a CD-ROM drive.

Short for "CD-ReWritable"; Similar to CD-R, although here data can be deleted and overwritten. CD-RW is also known as CDE (Compact Disc Eraseable).

An electrical signal path. In analog audio (such as a mixer), each channel consists of separate wired components. In the digital domain, channels may share wiring, and are kept separate through logical operations. MIDI provides definitions for 16 channels, which transmit not audio signals but digital control signals for triggering synthesizers and other devices.

channel pressure
A type of MIDI control message that is applied equally to all of the notes on a given channel; the opposite of poly pressure, in which each MIDI note has its own pressure value. Also called aftertouch, channel pressure is generated on keyboard instruments by pressing down on a key or keys while holding them down. See aftertouch, poly pressure.

An audio effect used to "expand" or "thicken" a sound by playing multiple versions of the input signal with slightly different delays and changes in pitch simulating an ensemble of the input sound. Chorus - an audio effect used to "expand" or "thicken" a sound by playing multiple versions of the input signal with slightly different delays and changes in pitch simulating an ensemble

A type of signal processing. In chorusing, a time-delayed or detuned copy of a signal is mixed with the original signal. The mixing process changes the relative strengths and phase relationships of the overtones to create a fatter, more animated sound. The simplest way to achieve chorusing is to detune one synthesizer oscillator from another to produce a slow beating between them.

Committee of the International Telecommunication Union. The International Telecommunication Union (ITU) is group that sets international communications standards.
They sponsor committees to provide detailed technical specifications for those international standards committee now known as the ITU.

Sounds containing partials that are not part of the natural harmonic series; clangorous tones often sound bell-like.of the input sound.

a) Frequency specification (usually in MHz) that describes how fast the computer can execute certain operations. The specification for processors is the most widely-known clock type; it pertains to the computing cycle of the CPU. Bus clock is also crucial to performance; it describes at which rate the CPU can communicate with other computer components via the busses.
b) Any of several types of timing control devices, or the periodic signals that they generate. A sequencer's internal clock is always set to some number of pulses per quarter-note (ppq), and this setting is one of the main factors that determine how precisely the sequencer can record time-dependent information. The actual clock speed is usually determined by the beats-per-minute setting. > ppq, bpm, MIDI clock.

clock resolution
The precision (measured in ppq) with which a sequencer can encode time-based information.

Stands for coder/decoder. Codecs are often used by software to compress and decompress audio data. For example, most Windows computers have an ADPCM codec which many software applications use to read and write compressed audio data from ADPCM compressed WAV files. You can view the codecs installed in Windows by going to Control Panel > Multimedia >

Color depth
Determines how many different colors a computer's graphical system can (and should) display simultaneously. Standard values are 8 bits (256 colors/Low Color), 16 bits (one thousand colors/High Color) and 32 bits (one million colors/True Color). High values give good visuals, but require a great deal of computing performance.

Comb filtering
Filter curve with steep notches, which in a graphical representation, resemble the teeth of a comb. Changes the timbre of a sound drastically and is usually considered an undesirable side effect caused by phase shifting, among others.

A type of signal processing in which the signal is compressed on input and expanded back to its original form on output. Digital companding enables a device to achieve a greater apparent dynamic range with fewer bits per sample word.

a) The process of reducing the amplitude range of an audio signal by reducing the peaks and bringing up the low levels.
b) The process of reducing a data file in size, often by noting patterns in the data and summarizing them. Some types of audio data compression are "lossy," meaning the quality of the audio is reduced.

continuous controller
A type of MIDI channel message that allows control changes to be made in notes that are currently sounding.
> controller.

a) Any device -- for example, a keyboard, wind synth controller, or pitch-bend lever -- capable of producing a change in some aspect of a sound by altering the action of some other device.
b) Any of the defined MIDI data types used for controlling the ongoing quality of a sustaining tone. Strictly speaking, MIDI continuous controllers are numbered from 0 to 122; in many synthesizers, the controller data category is more loosely defined to include pitch-bend and aftertouch data.

A mathematical operation producing a function from a certain kind of summation or integral of two other functions. In the time domain, one function may be the input signal, and the other the impulse response. The convolution than yields the result of applying that input to a system with the given impulse response. In DSP, the convolution of a signal with FIR filter coefficients results in the filtering of that signal.

crossfade looping
A sample-editing feature found in many samplers and most sample-editing software, in which some portion of the data at the beginning of a loop is mixed with some portion of the data at the end of the same loop, so as to produce a smoother transition between the end and the beginning when the loop plays.

A velocity threshold effect in a synthesizer in which one sound is triggered at low velocities and another at high velocities, with an abrupt transition between the two. If the transition is smooth rather than abrupt, the effect is called crossfading rather than crossswitching. Cross-switching can also be initiated from a footswitch, LFO, or some other controller. Also called velocity switching.

cutoff frequency
The point in the frequency spectrum beyond which a synthesizer filter attenuates the audio signal being sent through it.