System architecture for functional characterization of devices to mitigate hearing impairment

Abstract

Since 2000, claims of hearing loss by warfighters have doubled. It is the most frequently identified combat-related disability. Conventional audibility enhancement relies heavily on hearing aids, which do not provide sufficient sound intelligibility for a sizable subset of the hearing-impaired population. For them, there is a surgical option called a ‘cochlear implant’, a device which bypasses the damaged portions of the inner ear (cochlea) and provides direct neural stimulation. In this paper, we review the current state of the art in hearing aids and cochlear implants. A new device which has the potential for high spectral and temporal fidelity, the optical cochlear implant, is currently being tested in the laboratory. The projected development timeline spans many years: from point testing in the laboratory, through the approval process for limited human testing, with control gates for application to human candidates. A model-based development approach could potentially shorten this timeline. In this paper, we describe models and simulations that we developed to extend laboratory measurements in order to evaluate intelligibility impacts. Specifically, we describe our development of the Cochlear Laser Transduction Model, a physics-based simulator that evaluates tonotopic specificity; the Optical Cochlear Implant Simulator (OCIS), which can extend the laboratory measurements via simulation using the results of the Cochlear Laser Transduction Model; and the configuration of an off-the-shelf speech recognition tool to quickly assess intelligibility impacts, predicting system level impacts of varying optical cochlear implant design parameters. Results from the system-level modeling and simulation approach indicate that significant intelligibility improvements could be realized with the optical cochlear implant, with potential to offer upwards of 40 channels of spectral resolution compared with 10 channels with electrode-based implants.