This Recommendation is a supplementary guide for users of [ITU-T P.863], which describes a means of estimating listening speech quality by using reference and degraded speech samples. It assumes that an objective quality algorithm strictly conforms to [ITU-T P.863]. This can be confirmed by the conformance test provided in [ITU-T P. 863].

This Recommendation does not extend or narrow the scope of [ITU-T P.863]; rather, it provides necessary and important information for obtaining stable, reliable and meaningful objective measurement results in practice. It also provides example results for common situations and explanations for how certain degradations impact the score.

Additional characterization results will be added to this Recommendation, in the form of appendices, as this information becomes available.