ITU-T - P.341
(Pre-Published) Transmission characteristics for wideband digital loudspeaking and hands-free telephony terminals
|Publication Date:||1 March 2011|
This Recommendation provides audio performance requirements and test methods for loudspeaking and hands-free telephones capable of transmitting an audio bandwidth extending beyond the conventional telephony bandwidth of 300 to 3400 Hz, to a bandwidth of approximately 100 Hz to 8000 Hz. Such telephones are known as wideband audio telephones, and will make use of digital encoding schemes such as in [ITU-T G.722]. IP terminals may support other coding algorithms. Wideband audio telephones are expected to be used in new services such as high quality audio conferencing, videoconferencing and multimedia applications.
The requirements listed in this Recommendation are primarily applicable to telephones using G.722 encoding at 64 kbit/s, but should also be used as the basis of requirements for other wideband audio encoding schemes. This is still under study in ITU-T Study Group 12.
General information on hands-free terminals, which includes switching characteristics, can be found in [ITU-T P.340] and information on acoustic echo controllers in [ITU-T G.167].
For loudspeaking telephones which do not provide full hands-free operation, the relevant parts of this Recommendation may be used.
Conventional telephone band (300 Hz-3400 Hz) digital hands-free telephones using encoding according to [ITU-T G.711] and [ITU-T G.726] are covered by [ITU-T P.342]. Audio performance requirements for wideband headset terminals are included in [ITU T P.311]. Specifications for car mounted wideband hands-free terminals are included in [ITU-T P.1110]. Transmission characteristics for narrow-band cordless and mobile digital terminals are included in [ITU-T P.313].