Brainstem response estimation using continuous sound - A feasibility study

Abstract: Hearing loss is a complicated phenomena which does not only vary from person to person, but also, can change characteristics during the day. Despite this, hearing aids today are fitted only occasionally and thus only capture the slow changes in the hearing loss. In order for a hearing aid to continuously adapt to a subject’s hearing loss it has to be able to gauge the users hearing threshold. One way of measuring the hearing threshold is by examining the auditory brainstem response (ABR). The problem with measuring the ABR today is that it has to be measured as the response to a short sound that is repeated thousands of times. This masters thesis investigates a new method of estimating the brainstem’s response to continuous sound. This new paradigm builds on the assumption that the brainstem response corresponds to an impulse response to a system that takes the heard audio as input, and gives the EEG recording as output. This thesis explores how well this new paradigm works on hearing impaired people that use hearing aids. It verifies that the method works for finding the impulse responses that resemble the cortical response, which is a stronger and slower response. The method was however not successful when it came to finding the subcortical response. A possible reason for this is that a lot of the data needed to be removed due to outliers.