I joined the USA at the invitation of Dr. Charles Brown, Associate Professor of Psychology, in order to collaborate with him in building a new laboratory to study primate hearing and communication. The USA has provided us with an ideal environment totally supportive of primate research. This RCDA will allow me to develop my own research program independent of Dr. Brown and facilitate my promotion to a senior-level research rank. During the tenure of this award, I aim to obtain the required comparative data to write a theoretical article designed to evaluate evidence for differential use of the two primary auditory coding mechanisms (place vs. periodicity) in humans and other animals. I plan to become proficient in the technical aspects of managing a high-tech, state-of-the-art acoustic laboratory and to learn new techniques involved in the measurement and analysis of auditory evoked potentials. I will dedicate time for supervision and training of individual students who engage in research projects in our laboratory. My research compares the psychoacoustic capacities of humans, monkeys, and gerbils. Emphasis is on those tasks for which humans have been shown to perform markedly different from animals; e.g. pure tone frequency discrimination and forward and backward masking tasks. All species will be tested using the same stimuli, discrimination procedures, and threshold criteria. Animals will be trained with operant conditioning techniques and food reinforcement. The psychoacoustic performance of gerbils will be followed through their lifespans in order to develop an animal model for aging of the auditory system. Other experiments will compare humans' and monkeys' abilities to categorize musical tunes and monkey sounds in order to develop animal models for the perceptual processing of complex stimuli. The ultimate goal is to integrate data from humans, monkeys and other animals in order to more clearly delineate which aspects of human hearing are inherited from generalized mammalian vs. primate ancestors, and which are species-specific to humans.