Localisation of Virtual Sound Sources by Bilateral Cochlear Implant Users

Abstract

This thesis investigates the localisation of virtual sound sources by cochlear implant users. This research is intended to provide insight into the feasibility of utilising virtual sources to test their hearing abilities. In addition, it is hoped that the factors affecting the results can be determined by comparing the results to the patient demographic data. Listening tests were conducted with ten cochlear implant users and a control group of ten normal hearing subjects. Two methods of virtual sound source synthesis were applied: amplitude panning, via vector base amplitude panning, and time panning, via an empirical formula. A two alternative forced choice task was presented to the test subjects, and the results of the test were utilised to derive their minimum audible angle. It was found that amplitude panned sources can indeed be perceived by cochlear implant users and can, therefore, be utilised as a testing tool. Furthermore, it was found that the results were influenced by the age at which the subjects were diagnosed deaf and the time period between the diagnosis and implantation surgery.