This book deals fundamentally with the quality and usability of communication technology systems. To this end, the necessary terms are first introduced, and the fundamentals of psychophysics and psychometrics are established. Based on this, the cycle of human-oriented system development is presented. The measurement and prediction of quality and usability are then illustrated by practical examples of communication engineering systems. In particular, systems for information transmission (telephony, VoIP, IP-TV), speech dialog systems, and multimodal dialog systems are discussed. Finally,...