Extended Adaptive Multi-Rate – Wideband
Extended Adaptive Multi-Rate – Wideband (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 (transform coded excitation – TCX) additionally to ACELP. This greatly improves the generic audio coding.
Source: Wikipedia — Extended Adaptive Multi-Rate – Wideband (CC BY-SA 4.0)