Abstract :
Multimodal systems and services, enabling human-human communication as well as human-machine interaction through a number of different media, have now reached a level of maturity which allows for wide-spread applications. Examples include IP-based audio streaming and television, audio-visual conferences, multimodal information kiosks at airports or train stations, entertainment, edutainment and education systems, or smart home and office environments. Unfortunately, the number and diversity of applications does not automatically result in better services, at least from a user´s point of view. Thus, the quality experienced by users of such services has become a topic of paramount importance.
