Distortion-product otoacoustic emissions in normal and impaired ears: insight into generation processes

Otoacoustic emissions can be used to study cochlear function in an objective, non-invasive and rapid manner. These and other desirable features of emissions have inspired a significant amount of investigation into the practicalities of utilizing evoked emissions as clinical tests of hearing. Variables which affect the measurement of emissions can be sorted into two major categories consisting of factors affecting either emission generation or expression. The present report consolidates and summarizes recent findings of a series of experiments in our laboratory which address both the generation and expression of transiently evoked and distortion-product otoacoustic emissions. Because these two emission types have the greatest promise of becoming clinically useful, a complete understanding of the factors responsible for their measured properties is particularly important.