Methodology for Derivation of Equipment Impairment Factors from Subjective Listening-Only Tests Series P: Telephone Transmission Quality Telephone Installations Local Line Networks Methods for Objective and Subjective Assessment of Quality Study Group 12
The equipment impairment factor method (ITU-T Recommendation G.113) is now the only one recommended by ITU-T for describing the subjective effects of digital processes other than pure PCM on the integral quality for transmission planning purposes.