Nowadays OAE have a special role in electrophysiological examinations and also remarkable application in infants&apos hearing screening test. In the current article we have focused attention on the physiological fundamentals of OAE and tried to explain the trends in physiological studies that finally led to discovering the acoustic radiations by "David Kemp". By studying this article we can conclude that inner ear cannot be pondered just as a transformer that change the movements of the inner ear&aposs fluid to the neural signal, rather it should be considered as an active organ that can produce energy and also control the other active mechanisms involved in hearing.