This progress report covers the period from January, 1993 to January, 1994. First, we list the papers published during the period. Next, we list the papers submitted for publication and the papers presented at scientific meetings. The personnel are then listed, and, finally we conclude with a brief discussion of the problem areas in which future research efforts will be concentrated. We feel that more research should be devoted to this topic. Not only is this research needed to understand the basic stimulus variables in more detail, but it is needed in order to apply this research to real-world situations. In most realistic situations, the change in the auditory spectrum occurs at different times and with different degrees of synchrony among the components of the complex. Psychoacoustics.