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AMR-WB for Adaptive Multi-rate Wide Band. AMR refers to Adaptive Multi-rate Compression. It is a codec that was adopted by 3GPP for use over mobile networks, carrying speech data. AMR-WB (G.722.2) is an ITU-T standard speech codec and was developed after the original AMR-NB (Narrow Band) codec, and it provides much better quality for speech quality due to wider bandwidth being a factor, whereas AMR was optimized for lower bandwidth.
AMR-WB uses 9 different bitrates based on conditions, from lowest to highest: 6.60, 8.50, 12.65, 14.25, 15.85, 18.25, 19.85, 23.05 and 23.85kbit/s. AMR-WB provides provides superior quality to the narrow band-specific previous codec, but the lower bitrates are not considered "wideband speech" when forced to be used in bad conditions.
The higher bitrates can be used when background noise is present or there is audio data, for example. AMR-WB is standardized for usage in networks such as UMTS. The common file extension for AMR-WB is .awb.