26 series - Voice and audio codecs
The voice & audio specifications that are listed here cover the following issues:
- Echo control at the interface to the public switched telephone network.
- The acoustic characteristics of 3G phones.
- The codecs supported during transcoder-free operation, in which the compressed speech frames travel all the way from one mobile to the other, without any transcoders in the communication path.
- Text telephones for the hard-of-hearing.
- Distributed speech recognition, in which the speech is parameterised before transmission, so as to avoid degradation of the signal over the radio interface.
The codecs themselves (AMR, AMR-WB and enhanced aacPlus) are covered on the pages indicated at the top.
|AAC||Advanced audio coding|
|AMR-WB||Adaptive multi-rate wide-band|
|ETSI||European telecommunications standards institute|