Mental workload refers to a psychological construct that has wide currency in areas of applied psychology and human factors. The concept has been found to be useful in understanding why and how the many different tasks that people perform at home, work, and leisure are carried out effectively at times and not so successfully at others. Mental workload assessment has played an integral role in designing and evaluating many human-machine systems found in working environments, as well as in many other facets of life. A primary aim of this book and the chapters to come is to discuss factors that affect the mental workload associated with processing auditory information.