In research on innate constraints on vocal learning, avian species have been identified that learn selectively, accepting only conspecific vocalizations as models. New techniques of sound analysis and synthesis by computer will be used to specify acoustic features on which innate discriminations are based. Predispositions to extract clusters of notes as coherent "syllables" will be studied as a case of natural perceptual categories. A program of research will be conducted on the developmental basis of the temporal patterning of vocal behavior. Contributions of auditory feedback from production to this process will be analyzed. In parallel with laboratory studies on vocal perception and production in individuals reared under highly controlled conditions, field research will explore the nature and causes of enrichment of the perceptual processing of vocal sounds during the first year of life, including the role of self stimulation in the development of species song recognition. The aim is a synthesis of the interplay of innate and environmental influences in the development of perceptual processing of the complex acoustic signals used in avian communication.