This project will develop visiBabble, sound recognition software to provide real-time contingent visual reinforcement of vocalizations produced by infants or preschool children. This program is intended for children who are delayed in the frequency and variety of pre-speech vocalizations they produce and, hence, are at risk for being non-speaking. The visiBabble system will provide an automated training system to maintain and develop a child's skills as necessary for continued vocal development. It will expand the child's repertoire of voluntary communicative behaviors that can be interpreted by partners in functional and social interaction. The system will encourage infants to practice vocalizing and to explore a larger repertoire of phonetic patterns. Particularly, it will reinforce the production of syllabic utterances that are associated with later language and cognitive development. The first commercial version of visiBabble will be a teaching aid where an adult serving as a therapist, whether a parent, teacher, or clinician, could work with a child using the system. A second version will be appropriate as a floor or crib toy. In either case, the adult will be able to set visiBabble to respond to a particular aspect of the child's productions, e.g. syllable starts, pitch variation, duration of voicing, particular consonant types, or syllable complexity.