Subjective tests on the interoperability of the HR/FR/EFR speech codecs; single, tandem and tandem free operation
The present document contains the results obtained from an internationally co-ordinated subjective evaluation conducted by four laboratories to estimate the performance in mobile-to-mobile connections of the GSM half, full, and enhanced full rate speech codecs (including the expected advantages of the Tandem Free Operation), in case of inter-operability in the digital cellular telecommunications system. These (listening-only) tests did not include the effects of Voice Activity Detector, Comfort Noise Insertion and the Discontinuous Transmission.