Subjective evaluation of speech compression codecs and other non-linear voice-path devices for telephony applications

Subjectivity assessment plays a key role in characterizing the voice quality of new telecommunications devices, both individually & in conjunction with other network equipment. Subjective test methods for speech quality evaluation are discussed with focus on methods used to evaluate speech compression codecs & other non-linear digital speech processing techniques used in modern communications networks. Understanding test designs & trade-offs will help codec designers & network planners appreciate what subjective tests are capable of, what the results of the tests mean, & how the results of different tests may be compared. The general categories of listening tests & conversation tests are compared. Absolute & degradation category rating methods are considered, & the details of listening test design, testing procedure, data analysis, & interpretation of results are discussed in detail. 5 Figures, 17 References. Adapted from the source document