ITU-T Recommendations

This Recommendation describes the preferred method for calculating loudness ratings mainly in the case of local telephone systems which transmit a band of frequencies not exceeding about 180-4500 Hz.The purpose of using loudness ratings for telephone sets is two-fold: first, to provide the transmission planner with an adequate measure of how the sets perform in the network; second, to enable valid and unambiguous comparison between sets. Therefore, to avoid confusion, this version of this Recommendation contains only those telephone set loudness ratings which are of interest for these purposes.The improvement of the new version of this Recommendation is the addition of Annex G, which gives the W weights to extend the use of the general algorithm in the Recommendation for calculating sending and receiving loudness ratings of wideband (100 to 8000 Hz) terminals.