ITU-T Recommendation P.800 (08/96) provides methods for objective and subjective assessment of telephone transmission quality. It outlines procedures for conducting subjective evaluations of transmission quality, including the addition of an annex describing the Comparison Category Rating (CCR) procedure. The Recommendation aligns with recent revisions of Recommendation P.830 and was approved in August 1996. Key terms include Absolute Category Rating, Comparison Category Rating, conversational test, Degradation Category Rating, listening test, subjective evaluation, and subjective testing. The Recommendation describes methods for subjective testing of transmission quality, including conversation-opinion tests, listening-opinion tests, interview and survey tests, and other tests. It includes detailed procedures for test facilities, experiment design, conversation tasks, and test procedures. Annexes provide information on various testing methods, such as Absolute Category Rating (ACR), Degradation Category Rating (DCR), Comparison Category Rating (CCR), and the threshold method for comparing transmission systems with a reference system. The Recommendation emphasizes the importance of accurate test conditions, proper calibration, and strict control of variables to ensure reliable results. It also outlines the use of standardized opinion scales and statistical analysis for evaluating subjective test results. The document references other ITU-T Recommendations and standards for guidance on testing procedures and data analysis. The methods described are applicable to a wide range of transmission systems and are intended to be generally applicable regardless of the form of degradation factors present. The Recommendation provides detailed guidance on the preparation of speech material, processing of speech material, experiment philosophy, listening test procedures, and treatment of results.ITU-T Recommendation P.800 (08/96) provides methods for objective and subjective assessment of telephone transmission quality. It outlines procedures for conducting subjective evaluations of transmission quality, including the addition of an annex describing the Comparison Category Rating (CCR) procedure. The Recommendation aligns with recent revisions of Recommendation P.830 and was approved in August 1996. Key terms include Absolute Category Rating, Comparison Category Rating, conversational test, Degradation Category Rating, listening test, subjective evaluation, and subjective testing. The Recommendation describes methods for subjective testing of transmission quality, including conversation-opinion tests, listening-opinion tests, interview and survey tests, and other tests. It includes detailed procedures for test facilities, experiment design, conversation tasks, and test procedures. Annexes provide information on various testing methods, such as Absolute Category Rating (ACR), Degradation Category Rating (DCR), Comparison Category Rating (CCR), and the threshold method for comparing transmission systems with a reference system. The Recommendation emphasizes the importance of accurate test conditions, proper calibration, and strict control of variables to ensure reliable results. It also outlines the use of standardized opinion scales and statistical analysis for evaluating subjective test results. The document references other ITU-T Recommendations and standards for guidance on testing procedures and data analysis. The methods described are applicable to a wide range of transmission systems and are intended to be generally applicable regardless of the form of degradation factors present. The Recommendation provides detailed guidance on the preparation of speech material, processing of speech material, experiment philosophy, listening test procedures, and treatment of results.