AMR-WB

Adaptive Multi Rate – WideBand (AMR-WB) is a speech coding standard developed after the AMR using same technology like ACELP. The codec provides excellent speech quality due to wider speech bandwidth of 50–7000 Hz compared to narrowband speech codecs which in general are optimized for  POTS wireline quality of 300–3400 Hz. AMR-WB is codified as G.722.2, an ITU-T standard speech codec. A common file extension for AMR-WB is .awb.
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Adaptive Multi Rate – WideBand plus (AMR-WB+) is an audio codec that extends AMR-WB. It adds support for stereo signals and higher sampling rates. Another main improvement is the use of transform coding additionally to ACELP. This greatly improves the generic audio coding. Automatic switching between transform coding and ACELP provides both good speech and audio quality with moderate bit rates.
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