Editing Data compression (section)

===== Speech encoding =====
[[Speech encoding]] is an important category of audio data compression. The perceptual models used to estimate what aspects of speech a human ear can hear are generally somewhat different from those used for music. The range of frequencies needed to convey the sounds of a human voice is normally far narrower than that needed for music, and the sound is normally less complex. As a result, speech can be encoded at high quality using a relatively low bit rate.

This is accomplished, in general, by some combination of two approaches:
* Only encoding sounds that could be made by a single human voice.
* Throwing away more of the data in the signal—keeping just enough to reconstruct an "intelligible" voice rather than the full frequency range of human [[hearing]].

The earliest algorithms used in speech encoding (and audio data compression in general) were the [[A-law algorithm]] and the [[μ-law algorithm]].