The structural deficits associated with cleft palate are known to have adverse effects on resonance balance. Velopharyngeal inadequacy usually results in hypernasal resonance. On the other hand, impairment of the nasal and/or nasopharyngeal airway may produce a resonance alteration that is perceived as hyponasality. One aim of this proposal is to address the issue of hyponasal speech since nasal airway impairment is prevalent in about 70% of the cleft population. The specific questions to be addressed are: 1. What are the dimensions of the nasal and nasopharyngeal airway associated with hyponasal resonance in children and adults? 2. Is the site if airway constriction a factor in the perception of hyponasal resonance? 3. How does timing of velopharyngeal closure affect the perception of hyponasal speech? 4. What is the prevalence of hyponasality in the cleft population? Another line of inquiry represents an extension of current work dealing with the speech regulating system. The hypothesis that speech aerodynamics follows the rules of a physiologic regulating system implies that the brain receives information, processes it, and then directs the control activities. In particular, this suggests a detection system for sensing changes similar to the system that apparently operates during breathing. The following questions will be pursued: 1. What is the sensitivity of the detection system during speech? 2. What is the latency of the response to perturbations in the system? 3. Does extent of perturbation affect the latency of the response? 4. Is the sensitivity the same for equivalent increases and decreases in load? Aerodynamic techniques will be used to assess nasal, nasopharyngeal and velar function in normal and cleft lip/palate subjects during speech, breathing, and experimental perturbations. Additionally, acoustic rhinometry will be used to document the sites of nasal airway impairment. These studies should provide a more comprehensive understanding of the speech stigmata associated with clefts of the palate.