Summary

Recommendation ITU-T P.804 describes a subjective methodology for assessing and diagnosing the quality of transmitted speech in a telephone conversation. In addition to a score for the overall conversation quality, the methodology yields overall quality scores for three perceivable phases in a telephone conversation: listening, speaking, and interaction, as well as scores for their corresponding seven perceptual dimensions. Four of the perceptual dimension scores represent degradation associated with the listening phase, two are associated with the speaking phase, and one is associated with the interaction phase. Each of the perceptual dimension scores are based on ratings of the amount of degradation present in one system condition. The method is designed to be used with naïve subjects. The dimension scores can be used to provide diagnostic information on the causes of system degradations. The method is meant as a complement to standard conversation tests.