1. Appendix of IEEE Subcommittee on Subjective Measurements IEEE Recommended Practices for Speech Quality Measurements. (1969). IEEE Transactions on Audio and Electroacoustics. Vol 17, pp. 227–246.
2. European Telecommunications Standards Institute. (2008). Speech processing, transmission and quality aspects (STQ); speech quality performance in the presence of background noise part 3: Background noise transmission—Objective test methods. European Telecommunications Standards Institute, ETSI EG 202 396-3.
3. European Telecommunications Standards Institute. (2014). Speech and multimedia transmission quality (STQ); speech quality performance in the presence of background noise: Background noise transmission for mobile terminals—Objective test methods. European Telecommunications Standards Institute, ETSI TS 103 106.
4. Goodman, D. J., & Nash, R. D. (1982). Subjective quality of the same speech transmission conditions in seven different countries. IEEE Transactions on Communications, 30(4), 642–654.
5. 3GPP TR 26.952. (2015). Codec for Enhanced Voice Services (EVS); Performance Characterization.