Recommendation ITU-T G.160 applies to the characteristics, performance and testing of voice enhancement devices (VEDs) for use in digital network-based equipment. Such devices are commonly found in mobile networks and this version of this Recommendation is only applicable for mobile networks.
A VED is defined as certain signal processing network functions (SPNFs) (such as noise reduction and acoustic echo control) in the digital transmission path that perform voice enhancement functions on voiceband signals that traverse mobile networks.
Voice enhancement functions include the control of acoustic echo generated by wireless handsets, noise reduction, and the recognition and accommodation of tandem free operation (TFO) and interworking function (IWF) signals.
The current version of this Recommendation does not include certain tests that are still under study. In particular, it does not contain any objective tests covering voice quality performance of noise reduction functions, although a placeholder for such a test is given. In the meantime, the reader should be aware that voice quality performance of noise reduction functions is not addressed by this version of this Recommendation.
Appendix II presents an objective methodology for characterizing the basic effect of noise reduction (NR) methods and is accompanied by a reference ANSI-C source code. Three objective measures are specified for characterizing NR solutions. Recommendation target value ranges in specified conditions are given for the measures to serve as basic guidelines for proper functioning of NR methods.