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Glossary of Terms

ADPCM: (Adaptive Digital Pulse Code Modulation) An A/D conversion that produces a digital signal with a lower bit-rate than standard PCM. ADPCM produces a lower bit-rate by recording only the difference between samples and adjusting the coding scale dynamically to accommodate large and small differences.

A-Law: A companding method of digitally encoding analogue signals that is mostly used in Europe and elsewhere.

Bandwidth: A frequency range. For example the bandwidth of the human ear is around 20kHz.

Bit Depth: The number of bits (binary digits) used to define a sample.

Bit Rate: The number of kilobits per second (Kbps) of data in your audio file.

CCITT: (International Telegraph and Telephone Consultative Committee) A predecessor organization of the ITU-T.

CELP: (Code Excited Linear Prediction) A speech-coding algorithm. CELP coders use codebook excitation, a long-term pitch prediction filter, and a short-term format prediction filter.

CODEC: An algorithm for compressing and decompressing audio and video files.

Compress: Audio compression (not to be mistaken with data compression) is the process in which the dynamic range is reduced by making the loud parts quieter and the quiet parts louder.

Equalize: A process that allows emphasis or attenuation (boost or cut) of selected frequencies in the audio spectrum.

ITU: (International Telecommunication Union)

ITU-T: (International Telecommunication Union) Telecom Standardization Sector.

Kbps: (Kilobits per second)

kHz: (Kilohertz) Hertz is a unit of frequency. It replaces the old term (cycle per second).

Maximize: Similar to "Normalize", it is an enhanced process optimized for lifting the effective loudness of audio material.

Mu-Law: See "U-Law" below.

Noise Gate: A process that is used to eliminate low-level hiss, background noise and/or unwanted leakage.

PCM: (Pulse Code Modulation) A process of converting an analogue signal into the digital domain. The analogue signal is first sampled, then quantized and finally encoded into a bit stream.

Sample Rate: The number of times per second a digital audio signal is sampled - defined in kilohertz (kHz).

U-Law: Also known as Mu-Law. A companding method of digitally encoding analogue signals that is mostly used in the United States and Japan.

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