This project attempts to exploit the distinct information embedded in both reflection- and distortion-source OAEs to create a more comprehensive and descriptive assessment of cochlear function. At present, OAEs are used in a categorical sense, simply to detect hearing loss. However, the ample information offer by each OAE-source (i.e. linear reflection and nonlinear distortion) provides distinct clues about cochlear mechanics. We wish to exploit this distinct information describe (not just detect) sensorineural hearing loss (SNHL). At present, SNHL is a catch-all term, defined by degree of loss and audiometric configuration. However, two hearing losses with identical audiograms can produce varying perceptual difficulties and varied success with hearing aids. By recording reflection and distortion emissions together over a broad parametric space to examine level-dependence, we may be able to learn more about the underlying deficits that make up the broad category of SNHL. When used in combination, the properties embodied by each emission source can be considered in one metric. We are currently developing and testing this joint OAE protocol by recording stimulus frequency OAEs and the distortion component of DPOAEs in ears with normal and impaired hearing. We hypothesize that normal-hearing ears show a typical cluster of reflection-to-distortion features, and ears with hearing loss will show features that fall outside of this normative space. Furthermore, we expect that hearing impaired ears with common deficits will form clusters that provide useful in diagnostics and intervention. This project is conducted in conjunction with fellow USC faculty member, Dr. Christopher Shera.