Assessment of Cognitive Load, Speech Communication Quality and Quality of Experience for spatial and non-spatial audio conferencing calls

The operational characteristics and thus the quality of audio conferencing systems are affected by scalability issues in terms of the number of participants and communication devices, which can change between or even during calls. Towards the development of methods that can handle such scalability aspects, this work investigates the effect of changes in the communicative situation (i.e. Communication Complexity) and the system properties (i.e. Technical System Capability) on the user's quality perception. In a listening-only test, subjects evaluated for a set of artificial telephone conferences their impression of the perceived system performance (i.e. Speech Communication Quality), the perceived effort to follow the conversation (i.e. Cognitive Load), and the overall experience as such (i.e. Quality of Experience). The results showed that not only a technically more advanced system, but also a less complex communicative situation can improve quality perception. Consequently, the assessment of audio conferencing systems needs to incorporate the special communicative situation of such multiparty settings: the methods should avoid confusions between Speech Communication Quality and Quality of Experience; perceptual studies should control for or report on the Communication Complexity to facilitate comparability of studies; and instrumental approaches should incorporate an estimation of the Communication Complexity to improve performance.