Sebastian Möller Alexander Raake N. Kitawaki A. Takahashi Marcel Wältermann Impairment Factor Framework for Wide-Band Speech Codecs. 1969-1976 2006 14 IEEE Transactions on Audio, Speech & Language Processing 6 http://doi.ieeecomputersociety.org/10.1109/TASL.2006.883262 db/journals/taslp/taslp14.html#MollerRKTW06