Editing Companding (section)

==Applications==
Companding is used in digital telephony systems, compressing before input to an [[analog-to-digital converter]], and then expanding after a [[digital-to-analog converter]].  This is equivalent to using a non-linear ADC as in a [[T-carrier]] telephone system that implements [[A-law]] or [[μ-law]] companding.  This method is also used in digital file formats for better [[signal-to-noise ratio]] (SNR) at lower bit depths.  For example, a linearly encoded 16-bit [[PCM]] signal can be converted to an 8-bit [[WAV]] or [[au file format|AU]] file while maintaining a decent SNR by compressing before the transition to 8-bit and expanding after conversion back to 16-bit.  This is effectively a form of lossy [[audio data compression]].

Professional [[wireless microphone]]s do this since the dynamic range of the microphone audio signal itself is larger than the dynamic range provided by radio transmission. Companding also reduces the noise and crosstalk levels at the receiver.<ref>[http://www.audio-technica.com/cms/site/490e7be64dfcaa53/index.html A description of companding in wireless microphones]</ref>

Companders are used in concert audio systems and in some [[noise reduction scheme]]s.