1. ITU-T Rec. P. 800.1: Mean Opinion Score (MOS) terminology. International Telecommunication Union, Geneva, 2006.
2. Speech quality of VoIP: assessment and prediction;Raake,2007
3. ITU-T Rec. P.862: perceptual evaluation of speech quality (PESQ), an objective method for end-to-end speech quality assessment of narrowband telephone networks and speech codecs. International Telecommunication Union, Geneva, 2001.
4. ITU-T Rec. P.563: single-ended method for objective speech quality assessment in narrow-band telephony applications. International Telecommunication Union, Geneva, 2004.
5. ITU-T Rec. G. 107: the E-model, a computational model for use in transmission planning. International Telecommunication Union, 2003.