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.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

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Clause 5 describes the testing methodologies adopted for the internationally co-ordinated subjective evaluation of the interoperability HR-FR-EFR. Clause 6 describes the tools and procedures used by the host laboratory to produce the processed speech material (speech was added with environmental noise, when requested by the experimental design). Clause 7 describes the results obtained from the set of tests carried out by four laboratories. Clause 8 describes the conclusions that can be drawn from the analysis of all data that were produced over the two main phases of testing.