Reducing context effects in the subjective evaluation of speech quality
Mario Rossi, Chaslav V. Pavlovic, Robert Espesser · The Journal of the Acoustical Society of America · 1990
This study investigates whether the contextual invariance and subject invariance of categorical and magnitude estimates of speech quality could be improved by introducing a reference system and by normalizing the results with respect to it. One hundred and forty-four subjects were equally divided into 12 experimental groups and tested in various stimulus contexts using either a magnitude estimation (ME) or categorical estimation (CE) procedures. Various normalization procedures were compared to the nonnormalized results with respect to their immunity to the context/group effects. Different listening conditions were created by using various text-to-speech synthesis algorithms and external noise. The reference condition was natural speech. The results indicate that the introduction of a reference system and appropriate normalization algorithms is beneficial. [Work supported by a grant from the EEC Esprit SAM project.] Also at the Speech and Hearing Center, Univ. of Iowa, Iowa City, IA 52242.