This project is designed to explore the feasibility of a commercial dual-probe impedance test instrument. Two prototype systems will be constructed using two single probe instruments in each system. Crossed and uncrossed acoustic reflex measures will be simultaneously made with a probe in each ear. The instruments will be computer controlled. After development ten subjects will be tested at each of two different sites. One site is at Baylor College of Medicine, James Jerger, PhD., consultant to the project, and the other is at the Veterans Administration Hospital at Long Beach, Richard Wilson, PhD., Chief of Audiology, consultant to the project. Data will be correlated with a one-of-a-kind research system in use at Baylor. User interface techniques and commercial feasibility with respect to cost, technology, and ease of use for clinical purposes will be evaluated.