CCITT (Commité Consultatif International de Telecommunications et Telegraphie)
A committee of the International Telecommunications Union responsible for making technical recommendations about telephone and data communication systems for PTTs and suppliers. Plenary sessions are held every four years to adopt new standards.


CELP (Code-Excited Linear Prediction)
Audio encoding method for low-bit rate codecs.


Centre channel
An audio presentation channel used to stabilize the central component of the frontal stereo image.


Channel
A sequence of data representing an audio signal intended to be reproduced at one listening position.


Codec
Acronym for compressor/decompressor.


Coding parameters
The set of user-definable parameters that characterise a coded bitstream. Bitstreams are characterised by coding parameters. Decoders are characterised by the bitstreams that they are capable of decoding.


Compression
Reduction in the number of bits used to represent an item of data.


Constant bitrate
Operation where the bitrate is constant from start to finish of the compressed bitstream.


CRC
Cyclic Redundancy Check. CRC is used to detect any errors happened after encoding.


Critical band
This unit of bandwidth represents the standard unit of bandwidth expressed in human auditory terms, corresponding to a fixed length on the human cochlea. It is approximately equal to 100 Hz at low frequencies and 1/3 octave at higher frequencies, above approximately 700 Hz.