Perceptual QoS assessment methodologies for coded speech in networks

The paper reviews perceptual QoS assessment methodologies for coded speech in networks. The methods are mainly based on my contributions to the ITU-T Study Group 12 since 1981. First, quality factors in communications networks are analyzed, and then appropriate assessment methods for coded speech are discussed. Finally, the current status for perceptual QoS measurement methodologies is described from the viewpoint of a network planning tool for compound quality factors in communications networks.