This ITU-T Recommendation gives the algorithm for the so-called E-model as the common ITU-T Transmission Rating Model. This computational model can be useful to transmission planners, to help ensure that users will be satisfied with end-to-end transmission performance. The primary output of the model is a scalar rating of transmission quality. A major feature of this model is the use of transmission impairment factors that reflect the effects of modern signal processing devices.

This revision provides an enhanced version of the E-model to better take into account the effects of room noise at the send side, and quantizing distortion.