SUMMARY

The mammalian ear is a remarkable sensory system with wide dynamic range and sharp frequency selectivity that transduces sound waves in the air into nerve signals sent to the brain.
In addition to detecting sound, the cochlea (a fluid-filled part of the inner ear) can also generate sounds that may be measured in the ear canal to provide a noninvasive test of hearing functionality and loss. Distortion product otoacoustic emissions are a type of otoacoustic emissions that are generated in response to a two-tone stimulus. Although distortion product otoacoustic emissions are commonly used both clinically and in research to test for hearing functionality and hearing loss, questions remain on exactly where distortion products are generated and how they propagate within the cochlea.

This research proposes the investigation of the generation and propagation and generation of distortion product otoacoustic emissions. Determining where distortion products are generated and how they propagate will provide better understanding of the mechanics of the cochlea and better treatment and prevention of hearing loss.

In preliminary research, a computational model of the gerbil cochlea was used to study the propagation of distortion products within the cochlea. Two competing hypotheses have been given for how distortion products propagate with in the cochlea; in preliminary work these hypotheses were investigated with the computational model. In the proposed research, the effects of stimulus parameters and cochlear roughness on the onset of distortion product generation and locations of distortion product generation will be determined.