1. ETSI‘Digital cellular telecommunications system; EFR speech transcoding (GSM 06.06)’, ETS 300 700, 1997
2. Hayes, M.: ‘Statistical digital signal processing and modeling’, (John Wiley and Sons Inc. 1996), p. 371–379
3. Furui, S., and Sondhi, M.: ‘Advances in speech signal processing’, (Marcel Dekker Inc. 1991), p. 368–375
4. Objective estimation of perceived speech quality. I. Development of the measuring normalizing block technique